U.S. patent application number 14/628031 was filed with the patent office on 2016-05-05 for hybrid cloud data management system.
This patent application is currently assigned to RUBRIK, INC.. The applicant listed for this patent is RUBRIK, INC.. Invention is credited to Arpit Agarwal, Fabiano Botelho, Arvind Jain, Soham Mazumdar, Arvind Nithrakashyap.
Application Number | 20160125059 14/628031 |
Document ID | / |
Family ID | 55852697 |
Filed Date | 2016-05-05 |
United States Patent
Application |
20160125059 |
Kind Code |
A1 |
Jain; Arvind ; et
al. |
May 5, 2016 |
HYBRID CLOUD DATA MANAGEMENT SYSTEM
Abstract
Methods and systems for managing, storing, and serving data
within a virtualized environment are described. In some
embodiments, a data management system may manage the extraction and
storage of virtual machine snapshots, provide near instantaneous
restoration of a virtual machine or one or more files located on
the virtual machine, and enable secondary workloads to directly use
the data management system as a primary storage target to read or
modify past versions of data. The data management system may allow
a virtual machine snapshot of a virtual machine stored within the
system to be directly mounted to enable substantially instantaneous
virtual machine recovery of the virtual machine.
Inventors: |
Jain; Arvind; (Los Altos,
CA) ; Nithrakashyap; Arvind; (San Francisco, CA)
; Agarwal; Arpit; (Mountain View, CA) ; Mazumdar;
Soham; (San Francisco, CA) ; Botelho; Fabiano;
(San Ramon, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RUBRIK, INC. |
Palo Alto |
CA |
US |
|
|
Assignee: |
RUBRIK, INC.
Palo Alto
CA
|
Family ID: |
55852697 |
Appl. No.: |
14/628031 |
Filed: |
February 20, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62075112 |
Nov 4, 2014 |
|
|
|
Current U.S.
Class: |
707/639 |
Current CPC
Class: |
G06F 2009/45579
20130101; G06F 11/1464 20130101; H04L 61/2007 20130101; G06F
11/1453 20130101; H04L 9/3242 20130101; H04L 61/2061 20130101; G06F
11/1451 20130101; G06F 11/1458 20130101; G06F 16/148 20190101; G06F
2009/45562 20130101; H04L 9/3247 20130101; G06F 3/0641 20130101;
G06F 9/45558 20130101; G06F 9/5077 20130101; G06F 3/0665 20130101;
G06F 16/27 20190101; H04L 43/0817 20130101; G06F 16/13 20190101;
G06F 16/84 20190101; G06F 11/1448 20130101; G06F 2201/815 20130101;
G06F 11/1484 20130101; G06F 16/113 20190101; G06F 2201/80 20130101;
H04L 67/10 20130101; G06F 3/0619 20130101; G06F 3/067 20130101;
G06F 2201/84 20130101; G06F 3/0685 20130101; G06F 11/1435 20130101;
G06F 16/128 20190101; G06F 2009/4557 20130101; G06F 2009/45583
20130101; G06F 3/065 20130101; G06F 11/202 20130101; G06F 11/1446
20130101; G06F 11/1461 20130101 |
International
Class: |
G06F 17/30 20060101
G06F017/30; G06F 9/455 20060101 G06F009/455 |
Claims
1. A method for operating a data management system, comprising:
acquiring a first snapshot of a first virtual machine; storing a
full image associated with the first snapshot within a first
storage domain; receiving an instruction to transfer the first
snapshot to a second storage domain different from the first
storage domain; identifying a base image associated with a second
virtual machine different from the first virtual machine in
response to receiving the instruction; generating a dependent base
file using the full image and the base image; and transferring the
dependent base file to the second storage domain.
2. The method of claim 1, wherein: the first storage domain
includes a local storage appliance; the second storage domain
includes a remote storage appliance; the storing a full image
associated with the first snapshot includes storing the full image
using the local storage appliance, the full image comprises data
associated with one or more virtual disks of the first virtual
machine; and the transferring the dependent base file to the second
storage domain includes transferring the dependent base file to the
remote storage appliance.
3. The method of claim 1, wherein: the second storage domain is
associated with a cloud-based storage service; and the transferring
the dependent base file to the second storage domain includes
transferring the dependent base file to the cloud-based storage
service.
4. The method of claim 1, wherein: the identifying a base image
associated with the second virtual machine includes detecting that
the second virtual machine is stored within both the first storage
domain and the second storage domain and determining that the
second virtual machine comprises a virtual machine within the
second storage domain with the greatest amount of data similarity
between a first portion of the virtual machine and a corresponding
portion of the first virtual machine.
5. The method of claim 1, further comprising: storing the base
image associated with the second virtual machine within the first
storage domain; storing a copy of the base image associated with
the second virtual machine within the second storage domain;
generating a copy of the full image associated with the first
snapshot using the dependent base file and the copy of the base
image; and storing the copy of the full image associated with the
first snapshot within the second storage domain.
6. The method of claim 5, wherein: the first storage domain
includes a local storage appliance; the second storage domain
includes a remote storage appliance; the storing the base image
associated with the second virtual machine within the first storage
domain includes storing the base image using the local storage
appliance; the storing a copy of the base image associated with the
second virtual machine within the second storage domain includes
storing the copy of the base image using the remote storage
appliance; and the generating a copy of the full image associated
with the first snapshot includes patching the dependent base file
to the copy of the base image associated with the second virtual
machine using the remote storage appliance.
7. The method of claim 1, further comprising: acquiring one or more
snapshots of the first virtual machine, the first snapshot
corresponds with a first state of the first virtual machine at a
first point in time, the one or more snapshots correspond with
other states of the first virtual machine at points in time prior
to the first point in time; and storing one or more incremental
files corresponding with the one or more snapshots within the first
storage domain.
8. The method of claim 7, further comprising: detecting that the
first storage domain stores a number of snapshots for the first
virtual machine that is greater than a maximum number of snapshots
allowed for the first virtual machine within the first storage
domain; transferring a subset of the one or more incremental files
to the second storage domain in response to the detecting that the
first storage domain stores a number of snapshots for the first
virtual machine that is greater than a maximum number of snapshots
allowed for the first virtual machine within the first storage
domain; and deleting the subset of the one or more incremental
files from the first storage domain.
9. The method of claim 7, further comprising: acquiring a maximum
number of snapshots for the first virtual machine within the first
storage domain; determining that the one or more incremental files
associated with the one or more snapshots should be transferred to
the second storage domain based on the maximum number of snapshots
for the first virtual machine being exceeded; transferring the one
or more incremental files to the second storage domain; and
deleting the one or more incremental files from the first storage
domain.
10. The method of claim 7, further comprising: acquiring a maximum
age for snapshots within the first storage domain; detecting that
each snapshot of the one or more snapshots exceeds the maximum age
for snapshots within the first storage domain; transferring the one
or more incremental files to the second storage domain in response
to detecting that each snapshot of the one or more snapshots
exceeds the maximum age for snapshots within the first storage
domain; and deleting the one or more incremental files from the
first storage domain.
11. The method of claim 7, further comprising: acquiring a
threshold number of snapshots for the first virtual machine within
the first storage domain; determining that the one or more
incremental files associated with the one or more snapshots should
be transferred to the second storage domain based on the threshold
number of snapshots for the first virtual machine being exceeded;
and transferring the one or more incremental files to the second
storage domain.
12. A data management system, comprising: a memory, the memory
stores a full image associated with a first snapshot of a first
virtual machine, the full image comprises data associated with one
or more virtual disks of the first virtual machine; and one or more
processors in communication with the memory, the one or more
processors receive an instruction to transmit the first snapshot to
a remote storage domain, the one or more processors identify a base
image associated with a second virtual machine different from the
first virtual machine in response to receiving the instruction, the
one or more processors generate a dependent base file using the
full image and the base image, the one or more processors transmit
the dependent base file to the remote storage domain.
13. The data management system of claim 12, wherein: the remote
storage domain is associated with a cloud-based storage
service.
14. The data management system of claim 12, wherein: the one or
more processors identify the base image associated with the second
virtual machine by detecting that the second virtual machine is
stored within the remote storage domain and determining that the
second virtual machine comprises a virtual machine within the
remote storage domain with the greatest amount of data similarity
between a first portion of the virtual machine and a corresponding
portion of the first virtual machine.
15. The data management system of claim 12, further comprising: a
remote storage appliance within the remote storage domain, the
remote storage appliance stores a copy of the base image, the
remote storage appliance generates a copy of the full image using
the dependent base file and the copy of the base image, the remote
storage appliance stores the copy of the full image within the
remote storage appliance.
16. The data management system of claim 12, wherein: the one or
more processors acquire one or more snapshots of the first virtual
machine, the first snapshot corresponds with a first state of the
first virtual machine at a first point in time, the one or more
snapshots correspond with other states of the first virtual machine
at points in time prior to the first point in time; and the memory
stores one or more incremental files corresponding with the one or
more snapshots of the first virtual machine.
17. The data management system of claim 16, wherein: the one or
more processors detect that the memory stores a number of snapshots
for the first virtual machine that is greater than a maximum number
of snapshots allowed for the first virtual machine, the one or more
processors transfer a subset of the one or more incremental files
to the remote storage domain in response to detecting that the
memory stores more than the maximum number of snapshots allowed for
the first virtual machine.
18. The data management system of claim 16, wherein: the one or
more processors acquire a maximum number of snapshots for the first
virtual machine and determine that the one or more incremental
files associated with the one or more snapshots should be
transferred to the remote storage domain based on the maximum
number of snapshots for the first virtual machine being exceeded,
the one or more processors transfer the one or more incremental
files to the remote storage domain.
19. The data management system of claim 16, wherein: the one or
more processors acquire a maximum age for snapshots and detect that
each snapshot of the one or more snapshots exceeds the maximum age
for snapshots, the one or more processors transfer the one or more
incremental files to the remote storage domain in response to
detecting that each snapshot of the one or more snapshots exceeds
the maximum age for snapshots.
20. One or more storage devices containing processor readable code
for programming one or more processors to perform a method for
operating a data management system, the processor readable code
comprising: processor readable code configured to acquire a first
snapshot of a first virtual machine; processor readable code
configured to store a full image associated with the first snapshot
within a first storage domain, the full image comprises data
associated with one or more virtual disks of the first virtual
machine; processor readable code configured to receive an
instruction to transfer the first snapshot to a second storage
domain different from the first storage domain; processor readable
code configured to identify a base image associated with a second
virtual machine different from the first virtual machine in
response to receiving the instruction; processor readable code
configured to generate a dependent base file using the full image
and the base image; and processor readable code configured to
transfer the dependent base file to the second storage domain.
Description
CLAIM OF PRIORITY
[0001] The present application claims priority to U.S. Provisional
Application No. 62/075,112, entitled "Data Management System,"
filed Nov. 4, 2014, which is herein incorporated by reference in
its entirety.
BACKGROUND
[0002] Virtualization allows virtual hardware to be created and
decoupled from the underlying physical hardware. For example, a
hypervisor running on a host machine or server may be used to
create one or more virtual machines that may each run the same
operating system or different operating systems (e.g., a first
virtual machine may run a Windows.RTM. operating system and a
second virtual machine may run a Unix-like operating system such as
OS X.RTM.. A virtual machine may comprise a software implementation
of a physical machine. The virtual machine may include one or more
virtual hardware devices, such as a virtual processor, a virtual
memory, a virtual disk, or a virtual network interface card. The
virtual machine may load and execute an operating system and
applications from the virtual memory. The operating system and
applications used by the virtual machine may be stored using the
virtual disk. The virtual machine may be stored as a set of files
including a virtual disk file for storing the contents of a virtual
disk and a virtual machine configuration file for storing
configuration settings for the virtual machine. The configuration
settings may include the number of virtual processors (e.g., four
virtual CPUs), the size of a virtual memory, and the size of a
virtual disk (e.g., a 10 GB virtual disk) for the virtual
machine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1A depicts one embodiment of a networked computing
environment.
[0004] FIG. 1B depicts one embodiment of a server.
[0005] FIG. 1C depicts one embodiment of a storage appliance.
[0006] FIGS. 2A-2L depict various embodiments of sets of files and
data structures associated with managing and storing snapshots of
virtual machines.
[0007] FIG. 3A is a flowchart describing one embodiment of a
process for managing and storing virtual machine snapshots using a
data storage system.
[0008] FIG. 3B is a flowchart describing one embodiment of a
process for restoring a version of a virtual machine using a data
storage system.
[0009] FIG. 3C is a flowchart describing one embodiment of a
process for generating a dependent snapshot of a virtual machine
and generating one or more new versions of the virtual machine that
derive from the dependent snapshot using a data storage system.
[0010] FIGS. 4A-4B depict embodiments of stored files associated
with different versions of virtual machines.
[0011] FIGS. 4C-4D depict a flowchart describing one embodiment of
a process for managing and storing virtual machine snapshots using
a data storage system.
[0012] FIG. 5A depicts one embodiment of a virtual machine search
index.
[0013] FIG. 5B depicts one embodiment of a merged file for the
version A45 of Virtual Machine A referred to in FIG. 5A.
[0014] FIG. 5C depicts one embodiment of a first portion of a base
image and a second portion of the base image.
[0015] FIG. 5D is a flowchart describing one embodiment of a
process for extracting a particular version of a file from one or
more snapshots of a virtual machine.
[0016] FIGS. 6A-6H depict various embodiments of sets of files and
data structures associated with managing and storing snapshots of
virtual machines.
[0017] FIG. 6I is a flowchart describing one embodiment of a
process for storing snapshots of a virtual machine.
[0018] FIG. 6J is a flowchart describing one embodiment of a
process for generating a signature of a snapshot.
[0019] FIGS. 7A-7D depict various embodiments of sets of files and
data structures associated with managing and storing snapshots of
virtual machines.
[0020] FIG. 7E is a flowchart describing one embodiment of a
process for managing and storing snapshots of a virtual machine
using a hybrid local/remote data management system.
[0021] FIG. 8 is a flowchart describing one embodiment of a process
for generating a cloned virtual machine environment.
[0022] FIG. 9 is a flowchart describing one embodiment of a process
for operating a cluster-based file server.
DETAILED DESCRIPTION
[0023] Technology is described for managing, storing, and serving
data within a virtualized environment. In one embodiment, an
integrated data management and storage system may manage the
extraction and storage of historical snapshots associated with
different point in time versions of one or more virtual machines,
provide near instantaneous restoration of a virtual machine or one
or more files located on the virtual machine, and enable secondary
workloads (e.g., workloads for experimental or analytics purposes)
to directly use the integrated data management and storage system
as a primary storage target to read or modify past versions of
data. The integrated data management and storage system may provide
a unified primary and secondary storage system with built-in data
management that allows virtual machine snapshots of a virtual
machine stored within the system to be directly mounted or made
accessible in order to enable substantially instantaneous virtual
machine recovery of the virtual machine. In some cases, the
integrated data management and storage system may be used as both a
backup storage system and a "live" primary storage system for
primary workloads.
[0024] As virtualization technologies are adopted into information
technology (IT) infrastructures, there is a growing need for
recovery mechanisms to support mission critical application
deployment within a virtualized infrastructure. However, a
virtualized infrastructure may present a new set of challenges to
the traditional methods of data management due to the higher
workload consolidation and the need for instant, granular recovery.
An integrated data management and storage system may enable
substantially instantaneous recovery of applications running on the
virtual infrastructure without requiring the applications to be
restored first to a primary storage platform. The integrated data
management and storage system may provide a unified primary and
secondary storage system that allows virtual machine snapshots to
be directly mounted and used by secondary workloads, thereby
providing a non-passive data storage for backups and supporting
secondary workloads that require access to production data stored
on a primary storage platform used within a production environment.
The benefits of using an integrated data management and storage
system include the ability to reduce the amount of data storage
required to backup virtual machines, the ability to reduce the
amount of data storage required to support secondary workloads, the
ability to provide a non-passive storage target in which backup
data may be directly accessed and modified, and the ability to
quickly restore earlier versions of virtual machines and files.
[0025] FIG. 1A depicts one embodiment of a networked computing
environment 100 in which the disclosed technology may be practiced.
As depicted, the networked computing environment 100 includes a
data center 150, a storage appliance 140, and a computing device
154 in communication with each other via one or more networks 180.
The networked computing environment 100 may include a plurality of
computing devices interconnected through one or more networks 180.
The one or more networks 180 may allow computing devices and/or
storage devices to connect to and communicate with other computing
devices and/or other storage devices. In some cases, the networked
computing environment may include other computing devices and/or
other storage devices not shown. The other computing devices may
include, for example, a mobile computing device, a non-mobile
computing device, a server, a workstation, a laptop computer, a
tablet computer, a desktop computer, or an information processing
system. The other storage devices may include, for example, a
storage area network storage device, a networked-attached storage
device, a hard disk drive, a solid-state drive, or a data storage
system.
[0026] The data center 150 may include one or more servers, such as
server 160, in communication with one or more storage devices, such
as storage device 156. The one or more servers may also be in
communication with one or more storage appliances, such as storage
appliance 170. The server 160, storage device 156, and storage
appliance 170 may be in communication with each other via a
networking fabric connecting servers and data storage units within
the data center to each other. The storage appliance 170 may
include a data management system for backing up virtual machines
and/or files within a virtualized infrastructure. The server 160
may be used to create and manage one or more virtual machines
associated with a virtualized infrastructure. The one or more
virtual machines may run various applications, such as a database
application or a web server. The storage device 156 may include one
or more hardware storage devices for storing data, such as a hard
disk drive (HDD), a magnetic tape drive, a solid-state drive (SSD),
a storage area network (SAN) storage device, or a
networked-attached storage (NAS) device. In some cases, a data
center, such as data center 150, may include thousands of servers
and/or data storage devices in communication with each other. The
data storage devices may comprise a tiered data storage
infrastructure (or a portion of a tiered data storage
infrastructure). The tiered data storage infrastructure may allow
for the movement of data across different tiers of a data storage
infrastructure between higher-cost, higher-performance storage
devices (e.g., solid-state drives and hard disk drives) and
relatively lower-cost, lower-performance storage devices (e.g.,
magnetic tape drives).
[0027] The one or more networks 180 may include a secure network
such as an enterprise private network, an unsecure network such as
a wireless open network, a local area network (LAN), a wide area
network (WAN), and the Internet. The one or more networks 180 may
include a cellular network, a mobile network, a wireless network,
or a wired network. Each network of the one or more networks 180
may include hubs, bridges, routers, switches, and wired
transmission media such as a direct-wired connection. The one or
more networks 180 may include an extranet or other private network
for securely sharing information or providing controlled access to
applications or files.
[0028] A server, such as server 160, may allow a client to download
information or files (e.g., executable, text, application, audio,
image, or video files) from the server or to perform a search query
related to particular information stored on the server. In some
cases, a server may act as an application server or a file server.
In general, a server may refer to a hardware device that acts as
the host in a client-server relationship or a software process that
shares a resource with or performs work for one or more
clients.
[0029] One embodiment of server 160 includes a network interface
165, processor 166, memory 167, disk 168, and virtualization
manager 169 all in communication with each other. Network interface
165 allows server 160 to connect to one or more networks 180.
Network interface 165 may include a wireless network interface
and/or a wired network interface. Processor 166 allows server 160
to execute computer readable instructions stored in memory 167 in
order to perform processes described herein. Processor 166 may
include one or more processing units, such as one or more CPUs
and/or one or more GPUs. Memory 167 may comprise one or more types
of memory (e.g., RAM, SRAM, DRAM, ROM, EEPROM, Flash, etc.). Disk
168 may include a hard disk drive and/or a solid-state drive.
Memory 167 and disk 168 may comprise hardware storage devices.
[0030] The virtualization manager 169 may manage a virtualized
infrastructure and perform management operations associated with
the virtualized infrastructure. The virtualization manager 169 may
manage the provisioning of virtual machines running within the
virtualized infrastructure and provide an interface to computing
devices interacting with the virtualized infrastructure. In one
example, the virtualization manager 169 may set a virtual machine
into a frozen state in response to a snapshot request made via an
application programming interface (API) by a storage appliance,
such as storage appliance 170. Setting the virtual machine into a
frozen state may allow a point in time snapshot of the virtual
machine to be stored or transferred. In one example, updates made
to a virtual machine that has been set into a frozen state may be
written to a separate file (e.g., an update file) while the virtual
disk file associated with the state of the virtual disk at the
point in time is frozen. The virtual disk file may be set into a
read-only state to prevent modifications to the virtual disk file
while the virtual machine is in the frozen state. The
virtualization manager 169 may then transfer data associated with
the virtual machine (e.g., an image of the virtual machine or a
portion of the image of the virtual machine) to a storage appliance
in response to a request made by the storage appliance. After the
data associated with the point in time snapshot of the virtual
machine has been transferred to the storage appliance, the virtual
machine may be released from the frozen state (i.e., unfrozen) and
the updates made to the virtual machine and stored in the separate
file may be merged into the virtual disk file. The virtualization
manager 169 may perform various virtual machine related tasks, such
as cloning virtual machines, creating new virtual machines,
monitoring the state of virtual machines, moving virtual machines
between physical hosts for load balancing purposes, and
facilitating backups of virtual machines.
[0031] One embodiment of storage appliance 170 includes a network
interface 175, processor 176, memory 177, and disk 178 all in
communication with each other. Network interface 175 allows storage
appliance 170 to connect to one or more networks 180. Network
interface 175 may include a wireless network interface and/or a
wired network interface. Processor 176 allows storage appliance 170
to execute computer readable instructions stored in memory 177 in
order to perform processes described herein. Processor 176 may
include one or more processing units, such as one or more CPUs
and/or one or more GPUs. Memory 177 may comprise one or more types
of memory (e.g., RAM, SRAM, DRAM, ROM, EEPROM, NOR Flash, NAND
Flash, etc.). Disk 178 may include a hard disk drive and/or a
solid-state drive. Memory 177 and disk 178 may comprise hardware
storage devices.
[0032] In one embodiment, the storage appliance 170 may include
four machines. Each of the four machines may include a multi-core
CPU, 64 GB of RAM, a 400 GB SSD, three 4 TB HDDs, and a network
interface controller. In this case, the four machines may be in
communication with the one or more networks 180 via the four
network interface controllers. The four machines may comprise four
nodes of a server cluster. The server cluster may comprise a set of
physical machines that are connected together via a network. The
server cluster may be used for storing data associated with a
plurality of virtual machines, such as backup data associated with
different point in time versions of 1000 virtual machines.
[0033] The networked computing environment 100 may provide a cloud
computing environment for one or more computing devices. Cloud
computing may refer to Internet-based computing, wherein shared
resources, software, and/or information may be provided to one or
more computing devices on-demand via the Internet. The networked
computing environment 100 may comprise a cloud computing
environment providing Software-as-a-Service (SaaS) or
Infrastructure-as-a-Service (IaaS) services. SaaS may refer to a
software distribution model in which applications are hosted by a
service provider and made available to end users over the Internet.
In one embodiment, the networked computing environment 100 may
include a virtualized infrastructure that provides software, data
processing, and/or data storage services to end users accessing the
services via the networked computing environment. In one example,
networked computing environment 100 may provide cloud-based work
productivity or business related applications to a computing
device, such as computing device 154. The storage appliance 140 may
comprise a cloud-based data management system for backing up
virtual machines and/or files within a virtualized infrastructure,
such as virtual machines running on server 160 or files stored on
server 160.
[0034] In some cases, networked computing environment 100 may
provide remote access to secure applications and files stored
within data center 150 from a remote computing device, such as
computing device 154. The data center 150 may use an access control
application to manage remote access to protected resources, such as
protected applications, databases, or files located within the data
center. To facilitate remote access to secure applications and
files, a secure network connection may be established using a
virtual private network (VPN). A VPN connection may allow a remote
computing device, such as computing device 154, to securely access
data from a private network (e.g., from a company file server or
mail server) using an unsecure public network or the Internet. The
VPN connection may require client-side software (e.g., running on
the remote computing device) to establish and maintain the VPN
connection. The VPN client software may provide data encryption and
encapsulation prior to the transmission of secure private network
traffic through the Internet.
[0035] In some embodiments, the storage appliance 170 may manage
the extraction and storage of virtual machine snapshots associated
with different point in time versions of one or more virtual
machines running within the data center 150. A snapshot of a
virtual machine may correspond with a state of the virtual machine
at a particular point in time. In response to a restore command
from the server 160, the storage appliance 170 may restore a point
in time version of a virtual machine or restore point in time
versions of one or more files located on the virtual machine and
transmit the restored data to the server 160. In response to a
mount command from the server 160, the storage appliance 170 may
allow a point in time version of a virtual machine to be mounted
and allow the server 160 to read and/or modify data associated with
the point in time version of the virtual machine. To improve
storage density, the storage appliance 170 may deduplicate and
compress data associated with different versions of a virtual
machine and/or deduplicate and compress data associated with
different virtual machines. To improve system performance, the
storage appliance 170 may first store virtual machine snapshots
received from a virtualized environment in a cache, such as a
flash-based cache. The cache may also store popular data or
frequently accessed data (e.g., based on a history of virtual
machine restorations, incremental files associated with commonly
restored virtual machine versions) and current day incremental
files or incremental files corresponding with snapshots captured
within the past 24 hours.
[0036] An incremental file may comprise a forward incremental file
or a reverse incremental file. A forward incremental file may
include a set of data representing changes that have occurred since
an earlier point in time snapshot of a virtual machine. To generate
a snapshot of the virtual machine corresponding with a forward
incremental file, the forward incremental file may be combined with
an earlier point in time snapshot of the virtual machine (e.g., the
forward incremental file may be combined with the last full image
of the virtual machine that was captured before the forward
incremental was captured and any other forward incremental files
that were captured subsequent to the last full image and prior to
the forward incremental file). A reverse incremental file may
include a set of data representing changes from a later point in
time snapshot of a virtual machine. To generate a snapshot of the
virtual machine corresponding with a reverse incremental file, the
reverse incremental file may be combined with a later point in time
snapshot of the virtual machine (e.g., the reverse incremental file
may be combined with the most recent snapshot of the virtual
machine and any other reverse incremental files that were captured
prior to the most recent snapshot and subsequent to the reverse
incremental file).
[0037] The storage appliance 170 may provide a user interface
(e.g., a web-based interface or a graphical user interface) that
displays virtual machine backup information such as identifications
of the virtual machines protected and the historical versions or
time machine views for each of the virtual machines protected. A
time machine view of a virtual machine may include snapshots of the
virtual machine over a plurality of points in time. Each snapshot
may comprise the state of the virtual machine at a particular point
in time. Each snapshot may correspond with a different version of
the virtual machine (e.g., Version 1 of a virtual machine may
correspond with the state of the virtual machine at a first point
in time and Version 2 of the virtual machine may correspond with
the state of the virtual machine at a second point in time
subsequent to the first point in time).
[0038] The user interface may enable an end user of the storage
appliance 170 (e.g., a system administrator or a virtualization
administrator) to select a particular version of a virtual machine
to be restored or mounted. When a particular version of a virtual
machine has been mounted, the particular version may be accessed by
a client (e.g., a virtual machine, a physical machine, or a
computing device) as if the particular version was local to the
client. A mounted version of a virtual machine may correspond with
a mount point directory (e.g., /snapshots/VM5/Version23). In one
example, the storage appliance 170 may run an NFS server and make
the particular version (or a copy of the particular version) of the
virtual machine accessible for reading and/or writing. The end user
of the storage appliance 170 may then select the particular version
to be mounted and run an application (e.g., a data analytics
application) using the mounted version of the virtual machine. In
another example, the particular version may be mounted as an iSCSI
target.
[0039] FIG. 1B depicts one embodiment of server 160 in FIG. 1A. The
server 160 may comprise one server out of a plurality of servers
that are networked together within a data center. In one example,
the plurality of servers may be positioned within one or more
server racks within the data center. As depicted, the server 160
includes hardware-level components and software-level components.
The hardware-level components include one or more processors 182,
one or more memory 184, and one or more disks 185. The
software-level components include a hypervisor 186, a virtualized
infrastructure manager 199, and one or more virtual machines, such
as virtual machine 198. The hypervisor 186 may comprise a native
hypervisor or a hosted hypervisor. The hypervisor 186 may provide a
virtual operating platform for running one or more virtual
machines, such as virtual machine 198. Virtual machine 198 includes
a plurality of virtual hardware devices including a virtual
processor 192, a virtual memory 194, and a virtual disk 195. The
virtual disk 195 may comprise a file stored within the one or more
disks 185. In one example, a virtual machine may include a
plurality of virtual disks, with each virtual disk of the plurality
of virtual disks associated with a different file stored on the one
or more disks 185. Virtual machine 198 may include a guest
operating system 196 that runs one or more applications, such as
application 197.
[0040] The virtualized infrastructure manager 199, which may
correspond with the virtualization manager 169 in FIG. 1A, may run
on a virtual machine or natively on the server 160. The virtualized
infrastructure manager 199 may provide a centralized platform for
managing a virtualized infrastructure that includes a plurality of
virtual machines. The virtualized infrastructure manager 199 may
manage the provisioning of virtual machines running within the
virtualized infrastructure and provide an interface to computing
devices interacting with the virtualized infrastructure. The
virtualized infrastructure manager 199 may perform various
virtualized infrastructure related tasks, such as cloning virtual
machines, creating new virtual machines, monitoring the state of
virtual machines, and facilitating backups of virtual machines.
[0041] In one embodiment, the server 160 may use the virtualized
infrastructure manager 199 to facilitate backups for a plurality of
virtual machines (e.g., eight different virtual machines) running
on the server 160. Each virtual machine running on the server 160
may run its own guest operating system and its own set of
applications. Each virtual machine running on the server 160 may
store its own set of files using one or more virtual disks
associated with the virtual machine (e.g., each virtual machine may
include two virtual disks that are used for storing data associated
with the virtual machine).
[0042] In one embodiment, a data management application running on
a storage appliance, such as storage appliance 140 in FIG. 1A or
storage appliance 170 in FIG. 1A, may request a snapshot of a
virtual machine running on server 160. The snapshot of the virtual
machine may be stored as one or more files, with each file
associated with a virtual disk of the virtual machine. A snapshot
of a virtual machine may correspond with a state of the virtual
machine at a particular point in time. The particular point in time
may be associated with a time stamp. In one example, a first
snapshot of a virtual machine may correspond with a first state of
the virtual machine (including the state of applications and files
stored on the virtual machine) at a first point in time (e.g., 5:30
p.m. on Jun. 29, 2014) and a second snapshot of the virtual machine
may correspond with a second state of the virtual machine at a
second point in time subsequent to the first point in time (e.g.,
5:30 p.m. on Jun. 30, 2014).
[0043] In response to a request for a snapshot of a virtual machine
at a particular point in time, the virtualized infrastructure
manager 199 may set the virtual machine into a frozen state or
store a copy of the virtual machine at the particular point in
time. The virtualized infrastructure manager 199 may then transfer
data associated with the virtual machine (e.g., an image of the
virtual machine or a portion of the image of the virtual machine)
to the storage appliance. The data associated with the virtual
machine may include a set of files including a virtual disk file
storing contents of a virtual disk of the virtual machine at the
particular point in time and a virtual machine configuration file
storing configuration settings for the virtual machine at the
particular point in time. The contents of the virtual disk file may
include the operating system used by the virtual machine, local
applications stored on the virtual disk, and user files (e.g.,
images and word processing documents). In some cases, the
virtualized infrastructure manager 199 may transfer a full image of
the virtual machine to the storage appliance or a plurality of data
blocks corresponding with the full image (e.g., to enable a full
image-level backup of the virtual machine to be stored on the
storage appliance). In other cases, the virtualized infrastructure
manager 199 may transfer a portion of an image of the virtual
machine associated with data that has changed since an earlier
point in time prior to the particular point in time or since a last
snapshot of the virtual machine was taken. In one example, the
virtualized infrastructure manager 199 may transfer only data
associated with virtual blocks stored on a virtual disk of the
virtual machine that have changed since the last snapshot of the
virtual machine was taken. In one embodiment, the data management
application may specify a first point in time and a second point in
time and the virtualized infrastructure manager 199 may output one
or more virtual data blocks associated with the virtual machine
that have been modified between the first point in time and the
second point in time.
[0044] In some embodiments, the server 160 may or the hypervisor
186 may communicate with a storage appliance, such as storage
appliance 140 in FIG. 1A or storage appliance 170 in FIG. 1A, using
a distributed file system protocol such as Network File System
(NFS) Version 3. The distributed file system protocol may allow the
server 160 or the hypervisor 186 to access, read, write, or modify
files stored on the storage appliance as if the files were locally
stored on the server. The distributed file system protocol may
allow the server 160 or the hypervisor 186 to mount a directory or
a portion of a file system located within the storage
appliance.
[0045] FIG. 1C depicts one embodiment of storage appliance 170 in
FIG. 1A. The storage appliance may include a plurality of physical
machines that may be grouped together and presented as a single
computing system. Each physical machine of the plurality of
physical machines may comprise a node in a cluster (e.g., a
failover cluster). In one example, the storage appliance may be
positioned within a server rack within a data center. As depicted,
the storage appliance 170 includes hardware-level components and
software-level components. The hardware-level components include
one or more physical machines, such as physical machine 120 and
physical machine 130. The physical machine 120 includes a network
interface 121, processor 122, memory 123, and disk 124 all in
communication with each other. Processor 122 allows physical
machine 120 to execute computer readable instructions stored in
memory 123 to perform processes described herein. Disk 124 may
include a hard disk drive and/or a solid-state drive. The physical
machine 130 includes a network interface 131, processor 132, memory
133, and disk 134 all in communication with each other. Processor
132 allows physical machine 130 to execute computer readable
instructions stored in memory 133 to perform processes described
herein. Disk 134 may include a hard disk drive and/or a solid-state
drive. In some cases, disk 134 may include a flash-based SSD or a
hybrid HDD/SSD drive. In one embodiment, the storage appliance 170
may include a plurality of physical machines arranged in a cluster
(e.g., eight machines in a cluster). Each of the plurality of
physical machines may include a plurality of multi-core CPUs, 128
GB of RAM, a 500 GB SSD, four 4 TB HDDs, and a network interface
controller.
[0046] In some embodiments, the plurality of physical machines may
be used to implement a cluster-based network file server. The
cluster-based network file server may neither require nor use a
front-end load balancer. One issue with using a front-end load
balancer to host the IP address for the cluster-based network file
server and to forward requests to the nodes of the cluster-based
network file server is that the front-end load balancer comprises a
single point of failure for the cluster-based network file server.
In some cases, the file system protocol used by a server, such as
server 160 in FIG. 1A, or a hypervisor, such as hypervisor 186 in
FIG. 1B, to communicate with the storage appliance 170 may not
provide a failover mechanism (e.g., NFS Version 3). In the case
that no failover mechanism is provided on the client-side, the
hypervisor may not be able to connect to a new node within a
cluster in the event that the node connected to the hypervisor
fails.
[0047] In some embodiments, each node in a cluster may be connected
to each other via a network and may be associated with one or more
IP addresses (e.g., two different IP addresses may be assigned to
each node). In one example, each node in the cluster may be
assigned a permanent IP address and a floating IP address and may
be accessed using either the permanent IP address or the floating
IP address. In this case, a hypervisor, such as hypervisor 186 in
FIG. 1B may be configured with a first floating IP address
associated with a first node in the cluster. The hypervisor may
connect to the cluster using the first floating IP address. In one
example, the hypervisor may communicate with the cluster using the
NFS Version 3 protocol. Each node in the cluster may run a Virtual
Router Redundancy Protocol (VRRP) daemon. A daemon may comprise a
background process. Each VRRP daemon may include a list of all
floating IP addresses available within the cluster. In the event
that the first node associated with the first floating IP address
fails, one of the VRRP daemons may automatically assume or pick up
the first floating IP address if no other VRRP daemon has already
assumed the first floating IP address. Therefore, if the first node
in the cluster fails or otherwise goes down, then one of the
remaining VRRP daemons running on the other nodes in the cluster
may assume the first floating IP address that is used by the
hypervisor for communicating with the cluster.
[0048] In order to determine which of the other nodes in the
cluster will assume the first floating IP address, a VRRP priority
may be established. In one example, given a number (N) of nodes in
a cluster from node(0) to node(N-1), for a floating IP address (i),
the VRRP priority of node(j) may be (j-i) modulo N. In another
example, given a number (N) of nodes in a cluster from node(0) to
node(N-1), for a floating IP address (i), the VRRP priority of
node(j) may be (i-j) modulo N. In these cases, node(j) will assume
floating IP address (i) only if its VRRP priority is higher than
that of any other node in the cluster that is alive and announcing
itself on the network. Thus, if a node fails, then there may be a
clear priority ordering for determining which other node in the
cluster will take over the failed node's floating IP address.
[0049] In some cases, a cluster may include a plurality of nodes
and each node of the plurality of nodes may be assigned a different
floating IP address. In this case, a first hypervisor may be
configured with a first floating IP address associated with a first
node in the cluster, a second hypervisor may be configured with a
second floating IP address associated with a second node in the
cluster, and a third hypervisor may be configured with a third
floating IP address associated with a third node in the
cluster.
[0050] As depicted in FIG. 1C, the software-level components of the
storage appliance 170 may include data management system 102, a
virtualization interface 104, a distributed job scheduler 108, a
distributed metadata store 110, a distributed file system 112, and
one or more virtual machine search indexes, such as virtual machine
search index 106. In one embodiment, the software-level components
of the storage appliance 170 may be run using a dedicated
hardware-based appliance. In another embodiment, the software-level
components of the storage appliance 170 may be run from the cloud
(e.g., the software-level components may be installed on a cloud
service provider).
[0051] In some cases, the data storage across a plurality of nodes
in a cluster (e.g., the data storage available from the one or more
physical machines) may be aggregated and made available over a
single file system namespace (e.g., /snapshots/). A directory for
each virtual machine protected using the storage appliance 170 may
be created (e.g., the directory for Virtual Machine A may be
/snapshots/VM_A). Snapshots and other data associated with a
virtual machine may reside within the directory for the virtual
machine. In one example, snapshots of a virtual machine may be
stored in subdirectories of the directory (e.g., a first snapshot
of Virtual Machine A may reside in /snapshotsNM_A/s1/ and a second
snapshot of Virtual Machine A may reside in
/snapshots/VM_A/s2/).
[0052] The distributed file system 112 may present itself as a
single file system, in which as new physical machines or nodes are
added to the storage appliance 170, the cluster may automatically
discover the additional nodes and automatically increase the
available capacity of the file system for storing files and other
data. Each file stored in the distributed file system 112 may be
partitioned into one or more chunks. Each of the one or more chunks
may be stored within the distributed file system 112 as a separate
file. The files stored within the distributed file system 112 may
be replicated or mirrored over a plurality of physical machines,
thereby creating a load-balanced and fault tolerant distributed
file system. In one example, storage appliance 170 may include ten
physical machines arranged as a failover cluster and a first file
corresponding with a snapshot of a virtual machine (e.g.,
/snapshotsNM_A/s1/s1.full) may be replicated and stored on three of
the ten machines.
[0053] The distributed metadata store 110 may include a distributed
database management system that provides high availability without
a single point of failure. In one embodiment, the distributed
metadata store 110 may comprise a database, such as a distributed
document oriented database. The distributed metadata store 110 may
be used as a distributed key value storage system. In one example,
the distributed metadata store 110 may comprise a distributed NoSQL
key value store database. In some cases, the distributed metadata
store 110 may include a partitioned row store, in which rows are
organized into tables or other collections of related data held
within a structured format within the key value store database. A
table (or a set of tables) may be used to store metadata
information associated with one or more files stored within the
distributed file system 112. The metadata information may include
the name of a file, a size of the file, file permissions associated
with the file, when the file was last modified, and file mapping
information associated with an identification of the location of
the file stored within a cluster of physical machines. In one
embodiment, a new file corresponding with a snapshot of a virtual
machine may be stored within the distributed file system 112 and
metadata associated with the new file may be stored within the
distributed metadata store 110. The distributed metadata store 110
may also be used to store a backup schedule for the virtual machine
and a list of snapshots for the virtual machine that are stored
using the storage appliance 170.
[0054] In some cases, the distributed metadata store 110 may be
used to manage one or more versions of a virtual machine. Each
version of the virtual machine may correspond with a full image
snapshot of the virtual machine stored within the distributed file
system 112 or an incremental snapshot of the virtual machine (e.g.,
a forward incremental or reverse incremental) stored within the
distributed file system 112. In one embodiment, the one or more
versions of the virtual machine may correspond with a plurality of
files. The plurality of files may include a single full image
snapshot of the virtual machine and one or more incrementals
derived from the single full image snapshot. The single full image
snapshot of the virtual machine may be stored using a first storage
device of a first type (e.g., a HDD) and the one or more
incrementals derived from the single full image snapshot may be
stored using a second storage device of a second type (e.g., an
SSD). In this case, only a single full image needs to be stored and
each version of the virtual machine may be generated from the
single full image or the single full image combined with a subset
of the one or more incrementals. Furthermore, each version of the
virtual machine may be generated by performing a sequential read
from the first storage device (e.g., reading a single file from a
HDD) to acquire the full image and, in parallel, performing one or
more reads from the second storage device (e.g., performing fast
random reads from an SSD) to acquire the one or more
incrementals.
[0055] The distributed job scheduler 108 may be used for scheduling
backup jobs that acquire and store virtual machine snapshots for
one or more virtual machines over time. The distributed job
scheduler 108 may follow a backup schedule to backup an entire
image of a virtual machine at a particular point in time or one or
more virtual disks associated with the virtual machine at the
particular point in time. In one example, the backup schedule may
specify that the virtual machine be backed up at a snapshot capture
frequency, such as every two hours or every 24 hours. Each backup
job may be associated with one or more tasks to be performed in a
sequence. Each of the one or more tasks associated with a job may
be run on a particular node within a cluster. In some cases, the
distributed job scheduler 108 may schedule a specific job to be run
on a particular node based on data stored on the particular node.
For example, the distributed job scheduler 108 may schedule a
virtual machine snapshot job to be run on a node in a cluster that
is used to store snapshots of the virtual machine in order to
reduce network congestion.
[0056] The distributed job scheduler 108 may comprise a distributed
fault tolerant job scheduler, in which jobs affected by node
failures are recovered and rescheduled to be run on available
nodes. In one embodiment, the distributed job scheduler 108 may be
fully decentralized and implemented without the existence of a
master node. The distributed job scheduler 108 may run job
scheduling processes on each node in a cluster or on a plurality of
nodes in the cluster. In one example, the distributed job scheduler
108 may run a first set of job scheduling processes on a first node
in the cluster, a second set of job scheduling processes on a
second node in the cluster, and a third set of job scheduling
processes on a third node in the cluster. The first set of job
scheduling processes, the second set of job scheduling processes,
and the third set of job scheduling processes may store information
regarding jobs, schedules, and the states of jobs using a metadata
store, such as distributed metadata store 110. In the event that
the first node running the first set of job scheduling processes
fails (e.g., due to a network failure or a physical machine
failure), the states of the jobs managed by the first set of job
scheduling processes may fail to be updated within a threshold
period of time (e.g., a job may fail to be completed within 30
seconds or within 3 minutes from being started). In response to
detecting jobs that have failed to be updated within the threshold
period of time, the distributed job scheduler 108 may undo and
restart the failed jobs on available nodes within the cluster.
[0057] The job scheduling processes running on at least a plurality
of nodes in a cluster (e.g., on each available node in the cluster)
may manage the scheduling and execution of a plurality of jobs. The
job scheduling processes may include run processes for running
jobs, cleanup processes for cleaning up failed tasks, and rollback
processes for rolling-back or undoing any actions or tasks
performed by failed jobs. In one embodiment, the job scheduling
processes may detect that a particular task for a particular job
has failed and in response may perform a cleanup process to clean
up or remove the effects of the particular task and then perform a
rollback process that processes one or more completed tasks for the
particular job in reverse order to undo the effects of the one or
more completed tasks. Once the particular job with the failed task
has been undone, the job scheduling processes may restart the
particular job on an available node in the cluster.
[0058] The distributed job scheduler 108 may manage a job in which
a series of tasks associated with the job are to be performed
atomically (i.e., partial execution of the series of tasks is not
permitted). If the series of tasks cannot be completely executed or
there is any failure that occurs to one of the series of tasks
during execution (e.g., a hard disk associated with a physical
machine fails or a network connection to the physical machine
fails), then the state of a data management system may be returned
to a state as if none of the series of tasks were ever performed.
The series of tasks may correspond with an ordering of tasks for
the series of tasks and the distributed job scheduler 108 may
ensure that each task of the series of tasks is executed based on
the ordering of tasks. Tasks that do not have dependencies with
each other may be executed in parallel.
[0059] In some cases, the distributed job scheduler 108 may
schedule each task of a series of tasks to be performed on a
specific node in a cluster. In other cases, the distributed job
scheduler 108 may schedule a first task of the series of tasks to
be performed on a first node in a cluster and a second task of the
series of tasks to be performed on a second node in the cluster. In
these cases, the first task may have to operate on a first set of
data (e.g., a first file stored in a file system) stored on the
first node and the second task may have to operate on a second set
of data (e.g., metadata related to the first file that is stored in
a database) stored on the second node. In some embodiments, one or
more tasks associated with a job may have an affinity to a specific
node in a cluster. In one example, if the one or more tasks require
access to a database that has been replicated on three nodes in a
cluster, then the one or more tasks may be executed on one of the
three nodes. In another example, if the one or more tasks require
access to multiple chunks of data associated with a virtual disk
that has been replicated over four nodes in a cluster, then the one
or more tasks may be executed on one of the four nodes. Thus, the
distributed job scheduler 108 may assign one or more tasks
associated with a job to be executed on a particular node in a
cluster based on the location of data required to be accessed by
the one or more tasks.
[0060] In one embodiment, the distributed job scheduler 108 may
manage a first job associated with capturing and storing a snapshot
of a virtual machine periodically (e.g., every 30 minutes). The
first job may include one or more tasks, such as communicating with
a virtualized infrastructure manager, such as the virtualized
infrastructure manager 199 in FIG. 1B, to create a frozen copy of
the virtual machine and to transfer one or more chunks (or one or
more files) associated with the frozen copy to a storage appliance,
such as storage appliance 170 in FIG. 1A. The one or more tasks may
also include generating metadata for the one or more chunks,
storing the metadata using the distributed metadata store 110,
storing the one or more chunks within the distributed file system
112, and communicating with the virtualized infrastructure manager
that the virtual machine the frozen copy of the virtual machine may
be unfrozen or released for a frozen state. The metadata for a
first chunk of the one or more chunks may include information
specifying a version of the virtual machine associated with the
frozen copy, a time associated with the version (e.g., the snapshot
of the virtual machine was taken at 5:30 p.m. on Jun. 29, 2014),
and a file path to where the first chunk is stored within the
distributed file system 112 (e.g., the first chunk is located at
/snapshotsNM_B/s1/s1.chunk1). The one or more tasks may also
include deduplication, compression (e.g., using a lossless data
compression algorithm such as LZ4 or LZ77), decompression,
encryption (e.g., using a symmetric key algorithm such as Triple
DES or AES-256), and decryption related tasks.
[0061] The virtualization interface 104 may provide an interface
for communicating with a virtualized infrastructure manager
managing a virtualization infrastructure, such as virtualized
infrastructure manager 199 in FIG. 1B, and requesting data
associated with virtual machine snapshots from the virtualization
infrastructure. The virtualization interface 104 may communicate
with the virtualized infrastructure manager using an API for
accessing the virtualized infrastructure manager (e.g., to
communicate a request for a snapshot of a virtual machine). In this
case, storage appliance 170 may request and receive data from a
virtualized infrastructure without requiring agent software to be
installed or running on virtual machines within the virtualized
infrastructure. The virtualization interface 104 may request data
associated with virtual blocks stored on a virtual disk of the
virtual machine that have changed since a last snapshot of the
virtual machine was taken or since a specified prior point in time.
Therefore, in some cases, if a snapshot of a virtual machine is the
first snapshot taken of the virtual machine, then a full image of
the virtual machine may be transferred to the storage appliance.
However, if the snapshot of the virtual machine is not the first
snapshot taken of the virtual machine, then only the data blocks of
the virtual machine that have changed since a prior snapshot was
taken may be transferred to the storage appliance.
[0062] The virtual machine search index 106 may include a list of
files that have been stored using a virtual machine and a version
history for each of the files in the list. Each version of a file
may be mapped to the earliest point in time snapshot of the virtual
machine that includes the version of the file or to a snapshot of
the virtual machine that include the version of the file (e.g., the
latest point in time snapshot of the virtual machine that includes
the version of the file). In one example, the virtual machine
search index 106 may be used to identify a version of the virtual
machine that includes a particular version of a file (e.g., a
particular version of a database, a spreadsheet, or a word
processing document). In some cases, each of the virtual machines
that are backed up or protected using storage appliance 170 may
have a corresponding virtual machine search index.
[0063] In one embodiment, as each snapshot of a virtual machine is
ingested each virtual disk associated with the virtual machine is
parsed in order to identify a file system type associated with the
virtual disk and to extract metadata (e.g., file system metadata)
for each file stored on the virtual disk. The metadata may include
information for locating and retrieving each file from the virtual
disk. The metadata may also include a name of a file, the size of
the file, the last time at which the file was modified, and a
content checksum for the file. Each file that has been added,
deleted, or modified since a previous snapshot was captured may be
determined using the metadata (e.g., by comparing the time at which
a file was last modified with a time associated with the previous
snapshot). Thus, for every file that has existed within any of the
snapshots of the virtual machine, a virtual machine search index
may be used to identify when the file was first created (e.g.,
corresponding with a first version of the file) and at what times
the file was modified (e.g., corresponding with subsequent versions
of the file). Each version of the file may be mapped to a
particular version of the virtual machine that stores that version
of the file.
[0064] In some cases, if a virtual machine includes a plurality of
virtual disks, then a virtual machine search index may be generated
for each virtual disk of the plurality of virtual disks. For
example, a first virtual machine search index may catalog and map
files located on a first virtual disk of the plurality of virtual
disks and a second virtual machine search index may catalog and map
files located on a second virtual disk of the plurality of virtual
disks. In this case, a global file catalog or a global virtual
machine search index for the virtual machine may include the first
virtual machine search index and the second virtual machine search
index. A global file catalog may be stored for each virtual machine
backed up by a storage appliance within a file system, such as
distributed file system 112 in FIG. 1C.
[0065] The data management system 102 may comprise an application
running on the storage appliance that manages and stores one or
more snapshots of a virtual machine. In one example, the data
management system 102 may comprise a highest level layer in an
integrated software stack running on the storage appliance. The
integrated software stack may include the data management system
102, the virtualization interface 104, the distributed job
scheduler 108, the distributed metadata store 110, and the
distributed file system 112. In some cases, the integrated software
stack may run on other computing devices, such as a server or
computing device 154 in FIG. 1A. The data management system 102 may
use the virtualization interface 104, the distributed job scheduler
108, the distributed metadata store 110, and the distributed file
system 112 to manage and store one or more snapshots of a virtual
machine. Each snapshot of the virtual machine may correspond with a
point in time version of the virtual machine. The data management
system 102 may generate and manage a list of versions for the
virtual machine. Each version of the virtual machine may map to or
reference one or more chunks and/or one or more files stored within
the distributed file system 112. Combined together, the one or more
chunks and/or the one or more files stored within the distributed
file system 112 may comprise a full image of the version of the
virtual machine.
[0066] In some cases, the storage appliance 170 may comprise a
converged scale-out data management system that includes an
integrated software stack that protects application data, enables
near instant recovery of applications, and allows derivative
workloads (e.g., testing, development, and analytic workloads) to
use the storage appliance as a primary storage platform to read
and/or modify past versions of data. In one embodiment, the data
management system 102 may manage and store a plurality of point in
time versions of a virtual machine, receive an instruction to
restore a first version of the plurality of point in time versions
of the virtual machine (e.g., to restore the virtual machine to a
restore point), generate the first version in response to the
instruction to restore the first version, and output the first
version (e.g., transfer the first version to a primary storage
system). The first version may correspond with the most recent
snapshot of the virtual machine. The data management system 102 may
also receive a second instruction to restore a particular version
of a particular file (e.g., a word processing document or a
database file), determine a second version of the plurality of
point in time versions of the virtual machine that includes the
particular version of the particular file, extract the particular
version of the particular file from a portion of the second version
of the virtual machine (e.g., extracting the particular version of
the particular file without completely generating the full image of
the second version of the virtual machine), and output the
particular version of the particular file (e.g., by transferring
the particular version of the particular file to a server). In some
cases, a group of one or more files (e.g., associated with a file
folder) may be restored and outputted from the storage appliance
170 without requiring a full image of a virtual machine to be
generated or restored.
[0067] In another embodiment, the data management system 102 may
manage and store a plurality of point in time versions of a virtual
machine, receive an instruction to mount a particular version of
the plurality of point in time versions, generate a mounted version
of the virtual machine based on the particular version in response
to the instruction to mount the particular version, output a first
set of data associated with the mounted version, receive a second
set of data associated with one or more modifications to the
mounted version, and update the mounted version of the virtual
machine based on the second set of data. In parallel, while a
primary system has mounted the particular version of the virtual
machine and has the ability to access and/or modify data associated
with the particular version of the virtual machine, a copy of the
particular version of the virtual machine (e.g., the contents of a
virtual disk and configuration information associated with the
particular version) and any subsequent changes to the particular
version of the virtual machine may be transferred to the primary
system. In some cases, a primary system may automatically failover
or switch to the particular version stored on the storage appliance
170 and then automatically failback or switch back to the primary
system once the particular version of the virtual machine has been
transferred to the primary system. By allowing a primary system to
directly mount the particular version of the virtual machine, the
primary system may immediately bring up and use the particular
version of the virtual machine without first restoring and
transferring the particular version of the virtual machine to the
primary system. In some cases, to improve system performance and to
enable a non-passive storage system, the data management system 102
may generate and then store the mounted version of the virtual
machine in a cache, such as a flash-based cache.
[0068] In another embodiment, the data management system 102 may
manage and store a plurality of point in time versions of a virtual
machine, receive an instruction to generate a derivative version of
a first version of the plurality of point in time versions,
generate the derivative version in response to the instruction,
receive a second set of data associated with one or more
modifications to the derivative version, and update the derivative
version of the virtual machine based on the second set of data. By
allowing a system running a derivative workload to directly mount a
derivative version of a point in time version of the virtual
machine and read and/or modify data associated with the derivative
version, the derivative workload may be run using a backup storage
system for a primary system, thereby enabling a non-passive backup
system for the primary system. In one example, a new application
may be installed on a derivative version of a snapshot of a virtual
machine and run using the derivative version in order to test the
execution of the new application prior to installing the new
application within a production environment.
[0069] In some embodiments, a plurality of versions of a virtual
machine may be stored as a base file associated with a complete
image of the virtual machine at a particular point in time and one
or more incremental files associated with forward and/or reverse
incremental changes derived from the base file. The data management
system 102 may patch together the base file and the one or more
incremental files in order to generate a particular version of the
plurality of versions by adding and/or subtracting data associated
with the one or more incremental files from the base file or
intermediary files derived from the base file. In some embodiments,
each version of the plurality of versions of a virtual machine may
correspond with a merged file. A merged file may include pointers
or references to one or more files and/or one or more chunks
associated with a particular version of a virtual machine. In one
example, a merged file may include a first pointer or symbolic link
to a base file and a second pointer or symbolic link to an
incremental file associated with the particular version of the
virtual machine. In some embodiments, the one or more incremental
files may correspond with forward incrementals (e.g., positive
deltas), reverse incrementals (e.g., negative deltas), or a
combination of both forward incrementals and reverse
incrementals.
[0070] FIGS. 2A-2L depict various embodiments of sets of files and
data structures (e.g., implemented using merged files) associated
with managing and storing snapshots of virtual machines. FIGS.
2A-2L may be referred to when describing the processes depicted in
FIGS. 3A-3C.
[0071] FIG. 2A depicts one embodiment of a set of virtual machine
snapshots stored as a first set of files. The first set of files
may be stored using a distributed file system, such as distributed
file system 112 in FIG. 1C. As depicted, the first set of files
includes a set of reverse incrementals (R1-R4), a full image
(Base), and a set of forward incrementals (F1-F2). The set of
virtual machine snapshots includes different versions of a virtual
machine (versions V1-V7 of Virtual Machine A) captured at different
points in time (times T1-T7). In some cases, the file size of the
reverse incremental R3 and the file size of the forward incremental
F2 may both be less than the file size of the base image
corresponding with version V5 of Virtual Machine A. The base image
corresponding with version V5 of Virtual Machine A may comprise a
full image of Virtual Machine A at point in time T5. The base image
may include a virtual disk file for Virtual Machine A at point in
time T5. The reverse incremental R3 corresponds with version V2 of
Virtual Machine A and the forward incremental F2 corresponds with
version V7 of Virtual Machine A.
[0072] In some embodiments, each snapshot of the set of virtual
machine snapshots may be stored within a storage appliance, such as
storage appliance 170 in FIG. 1A. In other embodiments, a first set
of the set of virtual machine snapshots may be stored within a
first storage appliance and a second set of the set of virtual
machine snapshots may be stored within a second storage appliance,
such as storage appliance 140 in FIG. 1A. In this case, a data
management system may extend across both the first storage
appliance and the second storage appliance. In one example, the
first set of the set of virtual machine snapshots may be stored
within a local cluster repository (e.g., recent snapshots of the
file may be located within a first data center) and the second set
of the set of virtual machine snapshots may be stored within a
remote cluster repository (e.g., older snapshots or archived
snapshots of the file may be located within a second data center)
or a cloud repository.
[0073] FIG. 2B depicts one embodiment of a merged file for
generating version V7 of Virtual Machine A using the first set of
files depicted in FIG. 2A. The merged file includes a first pointer
(pBase) that references the base image Base (e.g., via the
path/snapshots/VM_A/s5/s5.full), a second pointer (pF1) that
references the forward incremental F1 (e.g., via the
path/snapshots/VM_A/s6/s6.delta), and a third pointer (pF2) that
references the forward incremental F2 (e.g., via the
path/snapshots/VM_A/s7/s7.delta). In one embodiment, to generate
the full image of version V7 of Virtual Machine A, the base image
may be acquired, the data changes associated with forward
incremental F1 may be applied to (or patched to) the base image to
generate an intermediate image, and then the data changes
associated with forward incremental F2 may be applied to the
intermediate image to generate the full image of version V7 of
Virtual Machine A.
[0074] FIG. 2C depicts one embodiment of a merged file for
generating version V2 of Virtual Machine A using the first set of
files depicted in FIG. 2A. The merged file includes a first pointer
(pBase) that references the base image Base (e.g., via the
path/snapshots/VM_A/s5/s5.full), a second pointer (pR1) that
references the reverse incremental R1 (e.g., via the
path/snapshots/VM_A/s4/s4.delta), a third pointer (pR2) that
references the reverse incremental R2 (e.g., via the
path/snapshots/VM_A/s3/s3.delta), and a fourth pointer (pR3) that
references the reverse incremental R3 (e.g., via the
path/snapshots/VM_A/s2/s2.delta). In one embodiment, to generate
the full image of version V2 of Virtual Machine A, the base image
may be acquired, the data changes associated with reverse
incremental R1 may be applied to the base image to generate a first
intermediate image, the data changes associated with reverse
incremental R2 may be applied to the first intermediate image to
generate a second intermediate image, and then the data changes
associated with reverse incremental R3 may be applied to the second
intermediate image to generate the full image of version V2 of
Virtual Machine A.
[0075] FIG. 2D depicts one embodiment of a set of virtual machine
snapshots stored as a second set of files after a consolidation
process has been performed using the first set of files in FIG. 2A.
The second set of files may be stored using a distributed file
system, such as distributed file system 112 in FIG. 1C. The
consolidation process may generate new files R12, R11, and Base2
associated with versions V5-V7 of Virtual Machine A in order to
move a full image closer to a more recent version of Virtual
Machine A and to improve the reconstruction time for the more
recent versions of Virtual Machine A. The data associated with the
full image Base in FIG. 2A may be equivalent to the new file R12
patched over R11 and the full image Base2. Similarly, the data
associated with the full image Base2 may be equivalent to the
forward incremental F2 in FIG. 2A patched over F1 and the full
image Base in FIG. 2A.
[0076] In some cases, the consolidation process may be part of a
periodic consolidation process that is applied at a consolidation
frequency (e.g., every 24 hours) to each virtual machine of a
plurality of protected virtual machines to reduce the number of
forward incremental files that need to be patched to a base image
in order to restore the most recent version of a virtual machine.
Periodically reducing the number of forward incremental files may
reduce the time to restore the most recent version of the virtual
machine as the number of forward incremental files that need to be
applied to a base image to generate the most recent version may be
limited. In one example, if a consolidation process is applied to
snapshots of a virtual machine every 24 hours and snapshots of the
virtual machine are acquired every four hours, then the number of
forward incremental files may be limited to at most five forward
incremental files.
[0077] As depicted, the second set of files includes a set of
reverse incrementals (R11-R12 and R1-R4) and a full image (Base2).
The set of virtual machine snapshots includes the different
versions of the virtual machine (versions V1-V7 of Virtual Machine
A) captured at the different points in time (times T1-T7) depicted
in FIG. 2A. In some cases, the file size of the reverse incremental
R2 may be substantially less than the file size of the base image
Base2. The reverse incremental R2 corresponds with version V2 of
Virtual Machine A and the base image Base2 corresponds with version
V7 of Virtual Machine A. In this case, the most recent version of
Virtual Machine A (i.e., the most recent restore point for Virtual
Machine A) comprises a full image. To generate earlier versions of
Virtual Machine A, reverse incrementals may be applied to (or
patched to) the full image Base2. Subsequent versions of Virtual
Machine A may be stored as forward incrementals that depend from
the full image Base2.
[0078] In one embodiment, a consolidation process may be applied to
a first set of files associated with a virtual machine in order to
generate a second set of files to replace the first set of files.
The first set of files may include a first base image from which a
first version of the virtual machine may be derived and a first
forward incremental file from which a second version of the virtual
machine may be derived. The second set of files may include a
second reverse incremental file from which the first version of the
virtual machine may be derived and a second base image from which
the second version of the virtual machine may be derived. During
the consolidation process, data integrity checking may be performed
to detect and correct data errors in the files stored in a file
system, such as distributed file system 112 in FIG. 1C, that are
read to generate the second set of files.
[0079] FIG. 2E depicts one embodiment of a merged file for
generating version V7 of Virtual Machine A using the second set of
files depicted in FIG. 2D. The merged file includes a first pointer
(pBase2) that references the base image Base2 (e.g., via the
path/snapshots/VM_A/s7/s7.full). In this case, the full image of
version V7 of Virtual Machine A may be directly acquired without
patching forward incrementals or reverse incrementals to the base
image Base2 corresponding with version V7 of Virtual Machine A.
[0080] FIG. 2F depicts one embodiment of a merged file for
generating version V2 of Virtual Machine A using the second set of
files depicted in FIG. 2D. The merged file includes a first pointer
(pBase2) that references the base image Base2 (e.g., via the
path/snapshots/VM_A/s7/s7.full), a second pointer (pR11) that
references the reverse incremental R11 (e.g., via the
path/snapshots/VM_A/s6/s6.delta), a third pointer (pR12) that
references the reverse incremental R12 (e.g., via the
path/snapshots/VM_A/s5/s5.delta), a fourth pointer (pR1) that
references the reverse incremental R1 (e.g., via the
path/snapshots/VM_A/s4/s4.delta), a fifth pointer (pR2) that
references the reverse incremental R2 (e.g., via the
path/snapshots/VM_A/s3/s3.delta), and a sixth pointer (pR3) that
references the reverse incremental R3 (e.g., via the
path/snapshots/VM_A/s2/s2.delta). In one embodiment, to generate
the full image of version V2 of Virtual Machine A, the base image
may be acquired, the data changes associated with reverse
incremental R11 may be applied to the base image to generate a
first intermediate image, the data changes associated with reverse
incremental R12 may be applied to the first intermediate image to
generate a second intermediate image, the data changes associated
with reverse incremental R1 may be applied to the second
intermediate image to generate a third intermediate image, the data
changes associated with reverse incremental R2 may be applied to
the third intermediate image to generate a fourth intermediate
image, and then the data changes associated with reverse
incremental R3 may be applied to the fourth intermediate image to
generate the full image of version V2 of Virtual Machine A.
[0081] FIG. 2G depicts one embodiment of a set of files associated
with multiple virtual machine snapshots. The set of files may be
stored using a distributed file system, such as distributed file
system 112 in FIG. 1C. As depicted, the set of files includes a set
of reverse incrementals (R1-R3), a full image (Base), and a set of
forward incrementals (F1-F2, F3, and F5-F6). In this case, a first
version of Virtual Machine B may be generated using a forward
incremental F3 that derives from Version VX of Virtual Machine A
and a second version of Virtual Machine C may be generated using
forward incrementals F5-F6 that are derived from Version VZ of
Virtual Machine A. In one example, Virtual Machine B may have been
initially cloned from Version VX of Virtual Machine A and Virtual
Machine C may have been initially cloned from Version VZ of Virtual
Machine A.
[0082] In one embodiment, in response to a failure of a first
virtual machine in a production environment (e.g., due to a failure
of a physical machine running the first virtual machine), a most
recent snapshot of the first virtual machine stored within a
storage appliance, such as storage appliance 170 in FIG. 1C, may be
mounted and made available to the production environment. In some
cases, the storage appliance may allow the most recent snapshot of
the first virtual machine to be mounted by a computing device
within the production environment, such as server 160 in FIG. 1A.
Once the most recent snapshot of the first virtual machine has been
mounted, data stored within the most recent snapshot of the first
virtual machine may be read and/or modified and new data may be
written without the most recent snapshot of the first virtual
machine being fully restored and transferred to the production
environment.
[0083] In another embodiment, a secondary workload may request that
a particular version of a virtual machine be mounted. In response
to the request, a storage appliance, such as storage appliance 170
in FIG. 1C, may clone the particular version of the virtual machine
to generate a new virtual machine and then make the new virtual
machine available to the secondary workload. Once the new virtual
machine has been mounted, data stored within the new virtual
machine may be read and/or modified and new data may be written to
the new virtual machine without changing data associated with the
particular version of the virtual machine stored within the storage
appliance.
[0084] FIG. 2H depicts one embodiment of a merged file for
generating version V1 of Virtual Machine B using the set of files
depicted in FIG. 2G. The merged file includes a first pointer
(pBase) that references the base image Base, a second pointer (pR1)
that references the reverse incremental R1, a third pointer (pR2)
that references the reverse incremental R2, and a fourth pointer
(pF3) that references the forward incremental F3. In one
embodiment, to generate the full image of version V1 of Virtual
Machine B, the base image associated with Version VY of Virtual
Machine A may be acquired, the data changes associated with reverse
incremental R1 may be applied to the base image to generate a first
intermediate image, the data changes associated with reverse
incremental R2 may be applied to the first intermediate image to
generate a second intermediate image, and the data changes
associated with forward incremental F3 may be applied to the second
intermediate image to generate the full image of version V1 of
Virtual Machine B.
[0085] FIG. 2I depicts one embodiment of a merged file for
generating version V2 of Virtual Machine C using the set of files
depicted in FIG. 2G. The merged file includes a first pointer
(pBase) that references the base image Base, a second pointer (pF1)
that references the forward incremental F1, a third pointer (pF5)
that references the forward incremental F5, and a fourth pointer
(pF6) that references the forward incremental F6. In one
embodiment, to generate the full image of version V2 of Virtual
Machine C, a base image (e.g., the base image associated with
Version VY of Virtual Machine A) may be acquired, the data changes
associated with forward incremental F1 may be applied to the base
image to generate a first intermediate image, the data changes
associated with forward incremental F5 may be applied to the first
intermediate image to generate a second intermediate image, and the
data changes associated with forward incremental F6 may be applied
to the second intermediate image to generate the full image of
version V2 of Virtual Machine C.
[0086] FIG. 2J depicts one embodiment of a set of files associated
with multiple virtual machine snapshots after a consolidation
process has been performed using the set of files in FIG. 2G. The
set of files may be stored using a distributed file system, such as
distributed file system 112 in FIG. 1C. The consolidation process
may generate new files R12, R11, and Base2. As depicted, the set of
files includes a set of reverse incrementals (R11-R12 and R1-R3), a
full image (Base2), and a set of forward incrementals (F3 and
F5-F7). In this case, a first version of Virtual Machine B may be
generated using a forward incremental F3 that derives from Version
VX of Virtual Machine A and a second version of Virtual Machine C
may be generated using forward incrementals F5-F6 that are derived
from Version VZ of Virtual Machine A. In one example, Virtual
Machine B may have been initially cloned from Version VX of Virtual
Machine A and Virtual Machine C may have been initially cloned from
version VZ of Virtual Machine A. Forward incremental file F7 may
include changes to Version VW of Virtual Machine A that occurred
subsequent to the generation of the full image file Base2. In some
cases, the forward incremental file F7 may comprise a writeable
file or have file permissions allowing modification of the file,
while all other files associated with earlier versions of Virtual
Machine A comprise read only files.
[0087] FIG. 2K depicts one embodiment of a merged file for
generating version V1 of Virtual Machine B using the set of files
depicted in FIG. 2J. The merged file includes a first pointer
(pBase2) that references the base image Base2, a second pointer
(pR11) that references the reverse incremental R11, a third pointer
(pR12) that references the reverse incremental R12, a fourth
pointer (pR1) that references the reverse incremental R1, a fifth
pointer (pR2) that references the reverse incremental R2, and a
sixth pointer (pF3) that references the forward incremental F3. In
one embodiment, to generate the full image of version V1 of Virtual
Machine B, a base image (e.g., the base image associated with
Version VW of Virtual Machine A) may be acquired, the data changes
associated with reverse incremental R11 may be applied to the base
image to generate a first intermediate image, the data changes
associated with reverse incremental R12 may be applied to the first
intermediate image to generate a second intermediate image, the
data changes associated with reverse incremental R1 may be applied
to the second intermediate image to generate a third intermediate
image, the data changes associated with reverse incremental R2 may
be applied to the third intermediate image to generate a fourth
intermediate image, and the data changes associated with forward
incremental F3 may be applied to the fourth intermediate image to
generate the full image of version V1 of Virtual Machine B.
[0088] FIG. 2L depicts one embodiment of a merged file for
generating version V2 of Virtual Machine C using the set of files
depicted in FIG. 2J. The merged file includes a first pointer
(pBase2) that references the base image Base2, a second pointer
(pR11) that references the reverse incremental R11, a third pointer
(pF5) that references the forward incremental F5, and a fourth
pointer (pF6) that references the forward incremental F6. In one
embodiment, to generate the full image of version V2 of Virtual
Machine C, a base image (e.g., the base image associated with
Version VW of Virtual Machine A) may be acquired, the data changes
associated with reverse incremental R11 may be applied to the base
image to generate a first intermediate image, the data changes
associated with forward incremental F5 may be applied to the first
intermediate image to generate a second intermediate image, and the
data changes associated with forward incremental F6 may be applied
to the second intermediate image to generate the full image of
version V2 of Virtual Machine C.
[0089] In some embodiments, a data storage system may include a
distributed scale-out software and storage stack that integrates
backup data management software with a storage target. The
distributed scale-out software may enable the data storage system
to be scalable and run using commodity hardware. The data storage
system may be used to backup one or more virtual machines running
within a virtualized environment or to backup one or more
applications associated with the one or more virtual machines. Via
communication with a virtualization manager, such as virtualization
manager 169 in FIG. 1A, the data storage system may discover the
one or more virtual machines within the virtualized environment and
capture snapshots of the one or more virtual machines over time.
Each captured snapshot may correspond with a virtual machine level
image of a virtual machine.
[0090] FIG. 3A is a flowchart describing one embodiment of a
process for managing and storing virtual machine snapshots using a
data storage system. In one embodiment, the process of FIG. 3A may
be performed by a storage appliance, such as storage appliance 170
in FIG. 1A.
[0091] In step 302, one or more virtual machines to be protected or
backed up are identified. The one or more virtual machines include
a first virtual machine. The one or more virtual machines may be
selected by an end user of a storage appliance, such as storage
appliance 170 in FIG. 1A, using a user interface provided by the
storage appliance. In step 304, a schedule for backing up the first
virtual machine is determined. In one example, the schedule for
backing up the first virtual machine may comprise periodically
backing up the first virtual machine every four hours. In step 306,
a job scheduler is configured to implement the schedule for backing
up the first virtual machine. In one example, a distributed job
scheduler, such as distributed job scheduler 108 in FIG. 1C, may be
configured to schedule and run processes for capturing and storing
images of the first virtual machine over time according the
schedule.
[0092] In step 308, a snapshot process for acquiring a snapshot of
the first virtual machine is initiated. The snapshot process may
send an instruction to a virtualized infrastructure manager, such
as virtualization manager 169 in FIG. 1A, that requests data
associated with the snapshot of the first virtual machine. In step
310, it is determined whether a full image of the first virtual
machine needs to be stored in order to store the snapshot of the
first virtual machine. The determination of whether a full image is
required may depend on whether a previous full image associated
with a prior version of the first virtual machine has been
acquired. If a full image needs to be stored, then step 311 is
performed. Otherwise, if a full image does not need to be stored,
then step 312 is performed. In step 311, the full image of the
first virtual machine is acquired. The full image of the first
virtual machine may correspond with a file or one or more data
chunks. In step 312, changes relative to a prior version of the
first virtual machine are acquired. The changes relative to the
prior version of the first virtual machine may correspond with a
file or one or more data chunks. In step 313, the full image of the
first virtual machine is stored in a distributed file system, such
as distributed file system 112 in FIG. 1C. In step 314, the changes
relative to the prior version of the first virtual machine are
stored in a distributed file system, such as distributed file
system 112 in FIG. 1C. In one embodiment, the full image of the
first virtual machine may be stored using a first storage device of
a first type (e.g., a HDD) and the changes relative to the prior
version of the first virtual machine may be stored using a second
storage device of a second type (e.g., an SSD).
[0093] In some embodiments, snapshots of the first virtual machine
may be ingested at a snapshot capture frequency (e.g., every 30
minutes) by a data storage system. When a snapshot of the first
virtual machine is ingested, the snapshot may be compared with
other snapshots stored within the data storage system in order to
identify a candidate snapshot from which the snapshot may depend.
In one example, a scalable approximate matching algorithm may be
used to identify the candidate snapshot whose data most closely
matches the data associated with the snapshot or to identify the
candidate snapshot whose data has the fewest number of data
differences with the snapshot. In another example, an approximate
matching algorithm may be used to identify the candidate snapshot
whose data within a first portion of the candidate snapshot most
closely matches data associated with a first portion of the
snapshot. In some cases, a majority of the data associated with the
snapshot and the candidate snapshot may be identical (e.g., both
the snapshot and the candidate snapshot may be associated with
virtual machines that use the same operation system and have the
same applications installed). Once the candidate snapshot has been
identified, then data differences (or the delta) between the
snapshot and the candidate snapshot may be determined and the
snapshot may be stored based on the data differences. In one
example, the snapshot may be stored using a forward incremental
file that includes the data differences between the snapshot and
the candidate snapshot. The forward incremental file may be
compressed prior to being stored within a file system, such as
distributed file system 112 in FIG. 1C.
[0094] In step 316, a merged file associated with the snapshot is
generated. The merged file may reference one or more files or one
or more data chunks that have been acquired in either step 311 or
step 312. In one example, the merged file may comprise a file or a
portion of a file that includes pointers to the one or more files
or the one or more data chunks. In step 318, the merged file is
stored in a metadata store, such as distributed metadata store 110
in FIG. 1C. In step 320, a virtual machine search index for the
first virtual machine is updated. The virtual machine search index
for the first virtual machine may include a list of files that have
been stored in the first virtual machine and a version history for
each of the files in the list. In one example, the virtual machine
search index for the first virtual machine may be updated to
include new files that have been added to the first virtual machine
since a prior snapshot of the first virtual machine was taken
and/or to include updated versions of files that were previously
stored in the first virtual machine.
[0095] FIG. 3B is a flowchart describing one embodiment of a
process for restoring a version of a virtual machine using a data
storage system. In one embodiment, the process of FIG. 3B may be
performed by a storage appliance, such as storage appliance 170 in
FIG. 1A.
[0096] In step 332, a particular version of a virtual machine to be
restored is identified. In step 334, a base image from which the
particular version may be derived is determined. In step 336, a set
of incremental files for generating the particular version is
determined. In one embodiment, the base image and the set of
incremental files may be determined from a merged file associated
with the particular version of the virtual machine. In some cases,
the set of incremental files may include one or more forward
incremental files and one or more reverse incremental files. In
step 338, a file associated with the particular version is
generated using the base image and the set of incremental files.
The file may be generated by patching the set of incremental files
onto the base image.
[0097] In one example, referring to FIG. 2G, if the particular
version corresponds with Version V2 of Virtual Machine C, then the
base image may correspond with the file Base in FIG. 2G and the set
of incremental files may correspond with files F1, F5, and F6 of
FIG. 2G. In another example, referring to FIG. 2G, if the
particular version corresponds with Version V1 of Virtual Machine
B, then the base image may correspond with the file Base in FIG. 2G
and the set of incremental files may correspond with files R1, R2,
and F3 of FIG. 2G. In step 340, at least a portion of the file is
outputted. The at least a portion of the file may be transferred to
a computing device, such as computing device 154 in FIG. 1A, or to
a virtualization manager, such as virtualization manager 169 in
FIG. 1A.
[0098] In some embodiments, the base image and a subset of the set
of incremental files may correspond with a second virtual machine
different from the virtual machine (e.g., the second virtual
machine may have been backed up prior to snapshots of the virtual
machine being acquired and used to generate a dependent base file
for the virtual machine). In this case, the base image may comprise
the base image for the second virtual machine and the set of
incremental files may include a dependent base file that comprises
data differences between the base image for the second virtual
machine and a previously acquired base image for the virtual
machine. Data deduplication techniques may be applied to identify a
candidate base image from which a dependent base file may depend
and to generate the dependent base file.
[0099] FIG. 3C is a flowchart describing one embodiment of a
process for generating a dependent snapshot of a virtual machine
and generating one or more new versions of the virtual machine that
derive from the dependent snapshot using a data storage system. In
one embodiment, the process of FIG. 3C may be performed by a
storage appliance, such as storage appliance 170 in FIG. 1A.
[0100] In step 352, a dependent snapshot to be generated is
identified. The dependent snapshot depends from a particular
version of a virtual machine (e.g., the most recent version of the
virtual machine or a prior point in time version of the virtual
machine). In one embodiment, the dependent snapshot may correspond
with a test snapshot of the particular version of the virtual
machine from which a new application may be installed and run prior
to releasing the new application into a production environment.
Changes to the test snapshot made by the new application may be
stored as one or more new versions that derive from the dependent
snapshot. In another embodiment, the dependent snapshot may
correspond with a mounted snapshot of the particular version of the
virtual machine from which a client may mount the mounted snapshot
of the particular version and make subsequent modifications to the
mounted snapshot. The subsequent modifications may be stored as one
or more new versions that derive from the dependent snapshot.
[0101] In step 354, a new merged file that corresponds with the
dependent snapshot is generated. In some cases, the new merged file
may comprise a duplicate copy of the merged file associated with
the particular version of the virtual machine. In one example,
referring to FIG. 2G, if the particular version corresponds with
Version VX of Virtual Machine A, then the new merged file may
comprise a duplicate copy of the merged file associated with
Version VX of Virtual Machine A. In this case, the new merged file
may be associated with a cloned virtual machine that comprises a
cloned version of Version VX of Virtual Machine A. In step 356, a
set of data associated with one or more changes to the dependent
snapshot is acquired. In step 358, the set of data is stored as a
new file. The new file may comprise a forward incremental file. In
one embodiment, the new file may be stored using a distributed file
system, such as distributed file system 112 and FIG. 1C. In another
embodiment, the new file may be stored using a flash-based cache or
an SSD. In step 360, the new merged file is updated with a pointer
to the new file in response to acquiring the set of data.
[0102] In one embodiment, the new file may correspond with changes
to a cloned virtual machine that comprises a cloned version of
Version VX of Virtual Machine A in FIG. 2G. The changes to the
cloned virtual machine may occur subsequent to the generation of
the cloned virtual machine. The new file may correspond with a
forward incremental file, such as forward incremental F3 in FIG.
2G. In one example, the changes to the cloned virtual machine may
be associated with a modification to a database stored on the
cloned virtual machine or the installation of a new application on
the cloned virtual machine.
[0103] In some cases, in response to a particular version of the
virtual machine being mounted, a storage appliance may generate a
dependent snapshot of the particular version of the virtual machine
in order to allow modifications to the dependent snapshot without
interfering with or corrupting the particular version of the
virtual machine. The dependent snapshot may correspond with a
cloned virtual machine that comprises a cloned version of the
particular version of the virtual machine. The dependent snapshot
may then be modified by a secondary workload that may read data
from the dependent snapshot and write data to the dependent
snapshot. In some cases, the dependent snapshot may comprise a new
full image of the particular version of the virtual machine that
may be directly modified by the secondary workload. In other cases,
modifications made to the dependent snapshot may be stored in a new
file (e.g., a forward incremental) that includes the changes in
data from the dependent snapshot.
[0104] In one embodiment, upon detection of a failure of a virtual
machine (e.g., due to a hardware failure), the most recent version
of the virtual machine stored within a storage appliance may be
identified and made available to an application requiring data from
the virtual machine. In some cases, the most recent version of the
virtual machine may be made available via a dependent snapshot or a
cloned virtual machine that comprises a cloned version of the most
recent version of the virtual machine. In cases where a dependent
snapshot has been generated, the application may read and/or modify
the data stored within the dependent snapshot without altering the
contents of the most recent version of the virtual machine stored
within the storage appliance. In one example, in response to
detecting a failure of a virtual machine or a failure of a virtual
disk of the virtual machine, a primary system may quickly mount the
most recent version of the virtual machine stored within a storage
appliance and then continue reading and writing data from the
mounted version without first restoring and transferring the most
recent version of the virtual machine to the primary system.
[0105] FIG. 4A depicts one embodiment of a first set of stored
files and a second set of stored files. The first set of stored
files may be associated with one or more virtual machines prior to
consolidation of the first set of stored files. The one or more
virtual machines may include an independent virtual machine (i.e.,
a virtual machine whose versions derive from merged files that do
not include pointers to data associated with a different virtual
machine) with six different versions that correspond with files
Base, R1-R3, and F1-F2. The one or more virtual machines may
include a first dependent virtual machine (i.e., a virtual machine
whose versions derive from merged files that include pointers to
data associated with an independent virtual machine) associated
with file F3 and a second dependent virtual machine associated with
files F5-F6.
[0106] The second set of files may include one or more new files
that have been generated using the first set of stored files in
order to consolidate the first set of files and to move a base
image file (e.g., the file Base) closer to a more recent version of
the independent virtual machine. As depicted, the one or more new
files include files R11, R12, and Base2 (i.e., a new base image
file). The one or more new files may correspond with a first
version of the independent virtual machine associated with the base
image (Base), a second version of the independent virtual machine
associated with the new base image (Base2), and the versions of the
independent virtual machine between the first version and the
second version. The second set of files may also include a forward
incremental file F7 that may include changes that have occurred
subsequent to the generation of the new base image file Base2.
[0107] In one embodiment, a first merged file representing a
version of the first dependent virtual machine associated with file
F3 may not need to be updated due to the relocation of the base
image file to a more recent version of the independent virtual
machine. However, a second merged file representing a version of
the second dependent virtual machine associated with file F5 may
need to be updated in order to point to the new file R11. In one
example, the second merged file may redirect a pointer from
pointing to the file F1 to point to the new file R11. Once the
second merged file has been updated from referencing the file F1 to
referencing the new file R11, then the file F1 may be released from
being stored or deleted.
[0108] FIG. 4B depicts one embodiment of a third set of stored
files. The third set of stored files may be associated with one or
more virtual machines after consolidation of the first set of
stored files in FIG. 4A. As depicted, the independent virtual
machine has six different versions that correspond with files
Base2, R1-R3, and R11-R12. The first dependent virtual machine is
associated with file F3 and the second dependent virtual machine is
associated with files F5-F6. The files Base and F1-F2 in FIG. 4A
have been deleted. Merged files associated with versions of the
second dependent virtual machine may include pointers to the new
file R11 and the new base image file Base2. In one embodiment, the
second dependent virtual machine may correspond with a cloned
version of the independent virtual machine that is being used by a
secondary workload. The secondary workload may be halted while the
merged files associated the second dependent virtual machine are
updated to include pointers to the new file R11. In another
embodiment, the merged files associated with versions of the second
dependent virtual machine may be updated to include pointers to the
new file R11 once all applications accessing the second dependent
virtual machine have been halted or terminated.
[0109] FIGS. 4C-4D depict a flowchart describing one embodiment of
a process for managing and storing virtual machine snapshots using
a data storage system. In one embodiment, the process of FIGS.
4C-4D may be performed by a storage appliance, such as storage
appliance 170 in FIG. 1A.
[0110] In step 402, a first set of files associated with a
plurality of versions of a first virtual machine to be consolidated
is identified. In one example, the first set of files may include a
base image file (e.g., generated during a previous consolidation
process) and one or more other files associated with versions of
the first virtual machine created after the base image file was
generated. The one or more other files may include one or more
forward incremental files. In one embodiment, the decision to
consolidate the first set of files or to generate a new base image
file such that the new base image file is closer to the most recent
version of the first virtual machine than the base image file may
be determined based on a consolidation frequency (e.g., files
associated with the first virtual machine may be consolidated every
8 hours, every 24 hours, or every 72 hours). In another embodiment,
the decision to consolidate the first set of files or to generate a
new base image file such that the new base image file is closer to
the most recent version of the first virtual machine than the base
image file may be determined based on a number of forward
incremental files that need to be patched to the base image file in
order to restore the most recent version of the first virtual
machine. In one example, if the number of forward incremental files
that need to be patched to the base image file in order to restore
the most recent version of the first virtual machine is greater
than a threshold number of forward incremental files (e.g., more
than ten forward incremental files), then the first set of files
may be consolidated or identified for consolidation. In another
embodiment, the decision to consolidate the first set of files may
be determined based on a data size threshold corresponding with a
summation of the file sizes for the forward incremental files that
need to be patched to the base image file in order to restore the
most recent version of the first virtual machine. In one example,
if the combined data size for the forward incremental files that
need to be patched to the base image file in order to restore the
most recent version of the first virtual machine is greater than a
threshold data size (e.g., the sum of the file sizes for the
forward incrementals is greater than 20 MB), then the first set of
files may be consolidated or identified for consolidation. In some
embodiments, the first set of files may be automatically
consolidated (e.g., without manual intervention) if a consolidation
period has passed or expired (e.g., it has been more than 12 hours
since the last consolidation occurred or since the base image file
was generated), the total number of forward incremental files that
need to be patched to the base image file in order to restore the
most recent version of the first virtual machine is greater than a
threshold number of forward incremental files, and/or the combined
data size for the forward incremental files that need to be patched
to the base image file in order to restore the most recent version
of the first virtual machine is greater than a threshold data
size.
[0111] In step 404, a first version of the plurality of versions
associated with a base file is determined. The base file may
comprise a full image (or a complete image) of the first version of
the first virtual machine. In step 406, a second version of the
plurality of versions associated with a new base file to be
generated is determined. The second version may correspond with a
newer version of the virtual machine than the first version. In one
example, the second version may comprise the most recent version of
the first virtual machine. The most recent version of the first
virtual machine may correspond with the latest or more recent
snapshot of the first virtual machine.
[0112] In step 408, the new base file is generated. In one example,
the new base file may be generated by generating a full image for
the second version. The new base file may be generated by patching
one or more forward incremental files to the base file. The one or
more forward incremental files may correspond with one or more
versions of the first virtual machine that were generated
subsequent to the first version. In one example, data changes
(e.g., bit differences) associated with a first forward incremental
file of the one or more forward incremental files may be applied to
the data stored in the base file to generate an intermediate full
image and data changes associated with a second forward incremental
file associated with the second version of the first virtual
machine may be applied to the intermediate full image to generate
the new base file. In one example, the new base file may correspond
with the new base image file Base2 in FIG. 4A.
[0113] In step 410, a first data integrity check is performed on
the new base file and/or on data read to generate the new base
file. In one example, as data is read from a file system, such as
distributed file system 112 in FIG. 1C, storing the base file and
one or more incremental files for generating the new base file,
checksums may be computed using the data and compared in order to
detect errors within the data. As the data may have been replicated
over a plurality of physical machines, such as physical machine 120
and physical machine 130 in FIG. 1C, if a data error is detected,
then the data error may be corrected using replicated data and the
corrected data (e.g., a new correct replica) may be written to one
or more of the plurality of physical machines. In another example,
as data is read from a file system to generate the new base file,
error correcting code (ECC) information may be generated based on
the data in order to detect and correct data errors that occurred
during transmission or storage of the data. Upon detection of one
or more data errors, the one or more data errors may be corrected
and the corrected data may be written to one or more of a plurality
of physical machines supporting the file system. One benefit of
performing a data integrity check as the new base file is generated
is that data storage reliability of a data storage system may be
improved.
[0114] In step 412, a set of reverse incremental files associated
with the first version and one or more versions of the first
virtual machine between the first version and the second version is
generated. The set of reverse incremental files may correspond with
data changes that derive from the new base file. In one example, a
first reverse incremental file of the set of reverse incremental
files may include the data changes (e.g., the bit differences) from
the new base file and a second reverse incremental file of the set
of reverse incremental files may include the data changes from the
new base file patched with the first reverse incremental file. In
one example, the set of reverse incremental files may correspond
with reverse incremental files R11-R12 in FIG. 4A. In some cases,
the set of reverse incremental files may be compressed prior to
being stored within a file system, such as distributed file system
112 in FIG. 1C. In step 414, a second data integrity check is
performed on the set of reverse incremental files and/or on data
read to generate the set of reverse incremental files. One benefit
of performing a data integrity check during consolidation or as the
set of reverse incremental files is generated is that data storage
reliability of a data storage system may be improved. Moreover,
periodically performing data integrity checks (e.g., during
periodic consolidations that occur on a daily or weekly basis) may
allow for a reduction in the degree of replication or a reduction
in the number of replicas stored within a cluster.
[0115] In step 416, the new base file is written to a first storage
device of a first type. In step 418, the set of reverse incremental
files is written to a second storage device of a second type. In
one example, the first storage device of a first type may comprise
a HDD and the second storage device of the second type a comprise
an SSD. In another example, the first storage device of the first
type may comprise a high density MLC flash-based SSD (e.g.,
2-bits/cell or 3-bits/cell) and the second storage device of the
second type may comprise a high performance SLC flash-based SSD. In
another example, the first storage device of the first type may
comprise a hybrid HDD/SSD drive and the second storage device of
the second type may comprise an SSD. In another example, the first
storage device of the first type may have a first read speed and/or
a first write speed and the second storage device of the second
type may have a second read speed that is faster than the first
read speed and/or a second write speed that is faster than the
first write speed. In another example, the first storage device of
the first type may have a first read latency and/or a first random
access time and the second storage device of the second type may
have a second read latency that is less than the first read latency
and/or a second random access time that is less than the first
random access time speed. One benefit of storing the new base file
in a first storage device of a first type and the set of reverse
incremental files in a second storage device of a second type is
that a particular version of the first virtual machine may be
quickly generated by performing a sequential read from the first
storage device (e.g., reading a single file from a HDD) to acquire
the new base file and, in parallel, performing one or more reads
from the second storage device (e.g., performing fast random reads
from an SSD) to acquire the set of reverse incremental files.
[0116] In step 420, a first set of merged files is updated to
reference the new base file. The first set of merged files may
correspond with merged files for the first version, the second
version, and the versions of the first virtual machine between the
first version and the second version. In one example, in reference
to FIG. 2G, the first version may correspond with Version VY of
Virtual Machine A, the second version may correspond with Version
VW of Virtual Machine A, and the versions of the first virtual
machine between the first version and the second version may
correspond with Version VZ of Virtual Machine A.
[0117] In step 422, a backup policy associated with the first
virtual machine is determined. The backup policy may specify one or
more parameters for backing up the first virtual machine in order
to recover information from the first virtual machine in the event
that the first virtual machine fails (e.g., due to a system
failure). In one example, the backup policy for the first virtual
machine may specify that at most a maximum number of versions of
the first virtual machine be stored (e.g., a data storage system
may store at most 100 backup versions of the first virtual
machine). In the case that the maximum number of versions to be
stored for a virtual machine is 100, the first 50 versions may
correspond with daily snapshots of the virtual machine covering the
past 50 days and the last 50 versions may correspond with weekly
snapshots of the virtual machine that cover the 50 weeks prior to
the past 50 days. The backup policy may specify that a first number
of historical snapshots of a virtual machine are stored for points
in time within a threshold date from a current date (e.g., that 30
snapshots are available covering the past 30 days) and that a
second number of historical snapshots of the virtual machine are
stored for points in time greater than the threshold date from the
current date (e.g., that 70 snapshots are available covering dates
prior to the past 30 days). The backup policy for the first virtual
machine may also specify that only versions of the first virtual
machine associated with point in time snapshots captured within a
particular period of time be stored (e.g., a data storage system
may only store backup versions of the first virtual machine
associated with point in time snapshots that were captured within
the past three years).
[0118] In one embodiment, the backup policy for the first virtual
machine may specify that versions of the first virtual machine
associated with points in time older than a particular time be
moved from a second storage device (e.g., an SSD) to a first
storage device (e.g., a HDD). In one example, incremental files
associated with versions of the first virtual machine older than a
particular time (e.g., older than six months ago) be transferred
from the second storage device to the first storage device. The
backup policy applied to a virtual machine may depend on a
classification of the virtual machine. In one example, a virtual
machine may be classified as a gold-level virtual machine, a
silver-level virtual machine, or a bronze-level virtual machine.
The backup policy for a gold-level virtual machine may specify a
greater maximum number of versions to be stored than a silver-level
virtual machine or a bronze-level virtual machine. The backup
policy for a gold-level virtual machine may specify a longer period
of time for storing versions of the virtual machine than a
silver-level virtual machine or a bronze-level virtual machine.
[0119] In one embodiment, a virtual machine may be automatically
classified, for example, as a gold-level virtual machine, a
silver-level virtual machine, or a bronze-level virtual machine
based on a history of restoration requests for snapshots of the
virtual machine. In one example, if more than ten snapshots of the
virtual machine have been restored within a week of a current date,
then the virtual machine may be automatically classified as a
gold-level virtual machine. In another example, if no request for a
restored snapshot of a virtual machine has been received within a
month of a current date, then the virtual machine may be
automatically classified as a bronze-level virtual machine. In
another embodiment, a virtual machine may be automatically
classified based on a history of snapshot mounting requests for
snapshots of the virtual machine. Once the virtual machine has been
automatically classified, then a particular backup policy for the
virtual machine may be applied to the virtual machine based on the
classification.
[0120] In step 424, a second set of reverse incremental files
associated with versions of the first virtual machine that are
older than the first version is identified based on the backup
policy. In one example, the second set of reverse incremental files
may correspond with versions of the first virtual machine that
correspond with points in time that occurred more than six months
from a current time. In another example, the second set of reverse
incremental files may correspond with versions of the first virtual
machine that correspond with points in time that occurred more than
one year from the time that the second version of the first virtual
machine was created or more than one year from the time that a
snapshot associated with the second version was captured. In step
426, the second set of reverse incremental files is moved from the
second storage device to the first storage device. In some cases,
the second set of reverse incremental files may be transferred from
an SSD to a HDD. The second set of reverse incremental files may be
transferred such that only the 50 most recent snapshots of the
first virtual machine are stored on the SSD and all other snapshots
of the first virtual machine that were captured prior to the 50
most recent snapshots are stored on the HDD.
[0121] In one embodiment, a second set of reverse incremental files
may be identified based on a backup policy associated with the
virtual machine. The backup policy may specify a maximum number of
snapshots allowed for the virtual machine for a particular time
period. In one example, the backup policy may specify that the
maximum number of snapshots for snapshots corresponding with points
in time that occurred more than six months from a current time must
not be greater than a first number (e.g., not more than 100
snapshots). The second set of reverse incremental files may then be
consolidated to free up storage space. In one example, the second
set of reverse incremental files may comprise ten reverse
incremental files and the second set of reverse incremental files
may be consolidated to generate a single consolidated file
corresponding with the earliest point in time snapshot of the ten
reverse incremental files.
[0122] In step 428, a second set of merged files is updated to
reference the new base file. The second set of merged files may
correspond with merged files for a second virtual machine that
include a pointer to the base file. The second virtual machine may
include dependent snapshots that depend on snapshots associated
with the first virtual machine. In step 430, it is detected that
there is no dependency on the first set of files. In one example,
it may be detected that there is no dependency on the first set of
files if there are no merged files that include pointers to any of
the first set of files. In step 432, the first set of files is
deleted in response to detecting that there is no dependency on the
first set of files. The first set of files may be deleted to free
up data storage space within a data storage system.
[0123] FIG. 5A depicts one embodiment of a virtual machine search
index, such as virtual machine search index 106 in FIG. 1C. A
virtual machine search index for a virtual machine may include a
list, table, or other data structure that stores mappings or
pointers from different versions of files stored on the virtual
machine to different versions of the virtual machine. As depicted,
the virtual machine search index includes a list of file versions
for File X that are stored on Virtual Machine A. The list of file
versions for File X includes Versions X1-X4. Each of the file
versions includes a pointer to a particular version of Virtual
Machine A that corresponds with the earliest point in time snapshot
of Virtual Machine A that includes the file version. For example,
version A23 of Virtual Machine A comprises the earliest point in
time snapshot of Virtual Machine A that includes version X1 of File
X and version A45 of Virtual Machine A comprises the earliest point
in time snapshot of Virtual Machine A that includes version X2 of
File X. The virtual machine search index also includes a list of
file versions for File Y that are stored on Virtual Machine A. The
list of file versions for File Y includes a mapping of version Y1
of File Y (saved at time T2) to version A45 of Virtual Machine A
and a mapping of version Y2 of File Y (saved at time T8 subsequent
to time T2) to version A95 of Virtual Machine A. Version A45 of
Virtual Machine A may comprise the 45.sup.th version of Virtual
Machine A.
[0124] FIG. 5B depicts one embodiment of a merged file for the
version A45 of Virtual Machine A referred to in FIG. 5A. The merged
file includes a first pointer (pBase) that references a base image
(e.g., via the path/snapshots/VM_A/s100/s100.full) and other
pointers to reverse incremental files (e.g., a pointer to reverse
incremental file R55 via the path/snapshots/VM_A/s45/s45.delta). In
this case, version A45 of Virtual Machine A may be generated by
patching 55 reverse incremental files onto the base image. However,
rather than patching the reverse incremental files onto the entire
base image, only a portion of the base image associated with a file
to be restored (e.g., version X2 of File X) may be acquired from a
file system and patched.
[0125] FIG. 5C depicts one embodiment of a first portion 502 of the
base image referenced by the first pointer (pBase) in FIG. 5B and a
second portion 504 of the base image referenced by the first
pointer (pBase) in FIG. 5B. In some cases, rather than restoring an
entire base image in order to restore a particular version of a
file, the first portion 502 of the base image may be restored in
order to identify a location of the file within the base image or
to identify one or more regions within the base image that store
the file. In one example, the first portion 502 of the base image
may correspond with one or more file system metadata files. The one
or more file system metadata files may store information regarding
the type of file system used and information regarding every file
and directory on a virtual volume or disk. In some cases, the one
or more file system metadata files may be located near the
beginning or the end of the base image or near the beginning or the
end of a virtual disk partition within the base image. The one or
more file system metadata files may include NTFS metadata files,
such as an NTFS Master File Table. The NTFS Master File Table may
include information for retrieving files from an NTFS partition.
The one or more file system metadata files may include a File
Allocation Table. The one or more file system metadata files may
include information for locating and retrieving files from a
virtual disk within the base image (even when due to fragmentation,
the file is located in multiple regions within the virtual
disk).
[0126] Once the first portion 502 of the base image has been
acquired and one or more regions within the base image are
identified that store the file to be restored, the one or more
regions of the base image including the second portion 504 of the
base image may be read and patched with data from one or more
reverse incremental files in order to generate a portion of a
particular version of a virtual machine from which the particular
version of the file may be extracted. Thus, a particular version of
a file may be quickly extracted by using the virtual machine search
index of FIG. 5A to identify a version of a virtual machine that
includes the particular version of the file and then restoring only
a portion of the version of the virtual machine that includes the
particular version of the file. One benefit of extracting the
particular version of the file from a small portion of the version
of the virtual machine (e.g., 2 MB) rather than from an entire
image of the version of the virtual machine (e.g., 20 GB) is that
the particular version of the file may be restored in a shorter
amount of time.
[0127] FIG. 5D is a flowchart describing one embodiment of a
process for extracting a particular version of a file from one or
more snapshots of a virtual machine. In one embodiment, the process
of FIG. 5D may be performed by a storage appliance, such as storage
appliance 170 in FIG. 1A.
[0128] In step 512, a particular version of a file to be restored
is identified. The file may be stored on a virtual disk of a
virtual machine. The file may comprise or correspond with a
database, a spreadsheet, a word processing document, an image file,
a video file, a text file, an executable file, an audio file, an
electronic message, or an email. The particular version of the file
may be selected by an end user of a storage appliance, such as
storage appliance 170 in FIG. 1A, using a user interface provided
by the storage appliance. In step 514, a virtual machine search
index, such as virtual machine search index 106 in FIG. 1C, for the
virtual machine is acquired. In step 516, a version of the virtual
machine that includes the particular version of the file is
identified using the virtual machine search index. In step 518, a
merged file corresponding with the version of the virtual machine
is acquired. In step 520, a base image for generating the version
of the virtual machine is identified using the merged file. In step
522, a set of incremental files for generating the version of the
virtual machine is identified using the merged file. In step 524, a
first portion of the base image that includes file system metadata
for the virtual disk storing the file is determined. In one
embodiment, the file system metadata may include information for
location and retrieving the file from the virtual disk. In one
example, the file system metadata includes NTFS metadata.
[0129] In step 526, a portion of the version of the virtual machine
is generated using the file system metadata and the set of
incremental files. In one embodiment, the portion of the version of
the virtual machine is generated by patching the set of incremental
files to a second portion of the base image. In another embodiment,
the portion of the version of the virtual machine is generated by
applying each of the set of incremental files to one or more chunks
of data located within the base image. In step 528, the particular
version of the file is extracted from the portion of the version of
the virtual machine. In step 530, the particular version of the
file is outputted. The particular version of the file may be
transferred to a computing device, such as computing device 154 in
FIG. 1A, or to a virtualization manager, such as virtualization
manager 169 in FIG. 1A. In one example, the outputted file may
correspond with a database that has been restored to a particular
version of the database without having to perform a full
restoration of an entire image of a virtual machine. One benefit of
extracting the particular version of the file from a portion of the
version of the virtual machine that includes the particular version
of the file is that the particular version of the file may be
quickly restored without having to first restore an entire image of
the version of the virtual machine.
[0130] In some embodiments, a particular version of a data object
to be restored may be identified. The particular version of the
data object may correspond with a particular point in time instance
of the data object (e.g., a third snapshot of an electronic
document captured at a third point in time). The data object may be
stored on a virtual disk of a virtual machine. The data object may
comprise a database, a spreadsheet, a word processing document, an
electronic document, an image, a video, a text file, an executable
file, an audio recording, an electronic message, or an email. A
version of the virtual machine that includes the particular version
of the data object may be identified using a virtual machine search
index. Once the version of the virtual machine has been identified,
metadata associated with the virtual machine (e.g., file system
metadata) may be read in order to identify one or more regions
within the virtual disk that store the data object. A portion of
the version of the virtual machine may then be generated by reading
and/or patching only the one or more regions within the virtual
disk that store the data object. The particular version of the data
object may then be extracted using only the portion of the version
of the virtual machine without having to extract or restore an
entire image of the version of the virtual machine.
[0131] FIG. 6A depicts one embodiment of a first set of stored
files associated with different versions of a Virtual Machine A (VM
A) and a second set of stored files associated with different
versions of a Virtual Machine B (VM B). The first set of stored
files includes a reverse incremental R1, base image Base
(corresponding with Version VX of Virtual Machine A), forward
incremental F1, and forward incremental F2 (corresponding with
Version VY of Virtual Machine A). The second set of stored files
includes a dependent base file Dependent_Base and forward
incrementals F7-F8. As depicted, the file Dependent_Base may
comprise a dependent base file that includes data differences that
may be applied to the base image for Virtual Machine A (Base) in
order to generate a first version (e.g., Version 1) of Virtual
Machine B. In some cases, the dependent base file may be considered
a forward incremental file that depends from the base image for
Virtual Machine A and may be used to generate the first version of
Virtual Machine B. One benefit of generating the first version of
Virtual Machine B using a dependent base file is that the versions
of Virtual Machine B may be stored using less storage space.
[0132] FIG. 6B depicts one embodiment of a merged file for
generating Version 1 of Virtual Machine B using the stored files
depicted in FIG. 6A. The merged file includes a first pointer
(pBase) that references the base image for Virtual Machine A (Base)
and a second pointer (pDependent_Base) that references the
dependent base file (Dependent_Base). In one embodiment, to
generate a full image for Version 1 of Virtual Machine B, the base
image (Base) for Virtual Machine A may be acquired and the data
changes associated with the dependent base file may be applied to
the base image to generate the full image for Version 1 of Virtual
Machine B.
[0133] FIG. 6C depicts one embodiment of a first set of stored
files associated with different versions of a Virtual Machine A (VM
A) and a second set of stored files associated with different
versions of a Virtual Machine B (VM B) after a first consolidation
process has been performed on the first set of files in FIG. 6A.
The first consolidation process may generate new files R12, R11,
and Base2. The new files may allow a base image for Virtual Machine
A to be moved closer to a more recent version of Virtual Machine A.
The first set of stored files includes a reverse incremental R1,
reverse incremental R11, reverse incremental R12 (corresponding
with Version VX of Virtual Machine A), and base image Base2
(corresponding with Version VY of Virtual Machine A). The second
set of stored files includes a dependent base file Dependent_Base
and forward incrementals F7-F8. As depicted, the file
Dependent_Base may comprise a dependent base file that includes
data differences that may be applied to a full image of Version VX
of Virtual Machine A in order to generate a first version (e.g.,
Version 1) of Virtual Machine B.
[0134] FIG. 6D depicts one embodiment of a merged file for
generating Version 1 of Virtual Machine B using the stored files
depicted in FIG. 6C. The merged file includes a first pointer
(pBase2) that references the base image for Virtual Machine A
(Base2), a second pointer (pR11) that references the reverse
incremental R11, a third pointer (pR12) that references the reverse
incremental R12, and a fourth pointer (pDependent_Base) that
references the dependent base file Dependent_Base. In one
embodiment, to generate the full image of Version 1 of Virtual
Machine B, the base image for Virtual Machine A (Base2) may be
acquired, the data changes associated with reverse incremental R11
may be applied to the base image to generate a first intermediate
image, the data changes associated with reverse incremental R12 may
be applied to the first intermediate image to generate a second
intermediate image, and the data changes associated with the
dependent base file Dependent_Base may be applied to the second
intermediate image to generate the full image for Version 1 of
Virtual Machine B.
[0135] FIG. 6E depicts one embodiment of a first set of stored
files associated with different versions of a Virtual Machine A (VM
A) and a second set of stored files associated with different
versions of a Virtual Machine B (VM B) after a second consolidation
process has been performed on the second set of files in FIG. 6C.
The second consolidation process may generate new files R22, R21,
and Dependent_Base2. The new files may allow a most recent version
of Virtual Machine B (e.g., Version 3 of Virtual Machine B) to move
closer to the base image for Virtual Machine A. The first set of
stored files includes a reverse incremental R1, reverse incremental
R11, reverse incremental R12 (corresponding with Version VX of
Virtual Machine A), and base image Base2 (corresponding with
Version VY of Virtual Machine A). The second set of stored files
includes a dependent base file Dependent_Base2 and reverse
incrementals R21-R22. As depicted, the file Dependent_Base2 may
comprise a dependent base file that includes data differences that
may be applied to a full image of Version VY of Virtual Machine A
in order to generate a most recent version (e.g., Version 3) of
Virtual Machine B.
[0136] FIG. 6F depicts one embodiment of a merged file for
generating Version 1 of Virtual Machine B using the stored files
depicted in FIG. 6E. The merged file includes a first pointer
(pBase2) that references the base image for Virtual Machine A
(Base2), a second pointer (pDependent_Base2) that references the
dependent base file Dependent_Base2, a third pointer (pR21) that
references the reverse incremental R21, and a fourth pointer (pR22)
that references the reverse incremental R22. In one embodiment, to
generate the full image of Version 1 of Virtual Machine B, the base
image (Base2) for Virtual Machine A may be acquired, the data
changes associated with the dependent base file Dependent_Base2 may
be applied to the base image to generate a first intermediate
image, the data changes associated with the reverse incremental R21
may be applied to the first intermediate image to generate a second
intermediate image, and the data changes associated with the
reverse incremental R22 may be applied to the second intermediate
image to generate the full image for Version 1 of Virtual Machine
B.
[0137] FIG. 6G depicts one embodiment of a first set of stored
files associated with different versions of a Virtual Machine A (VM
A), a second set of stored files associated with different versions
of a Virtual Machine B (VM B), and a third set of stored files
associated with different versions of a Virtual Machine C (VM C).
The first set of stored files includes a reverse incremental R1,
base image Base, and forward incrementals F1-F2. The second set of
stored files includes a first dependent base file Dependent_Base
and forward incrementals F7-F8. The third set of stored files
includes a second dependent base file Dependent_Base3 and forward
incremental F15. As depicted, the file Dependent_Base may comprise
a first dependent base file that includes data differences that may
be applied to the base image for Virtual Machine A (Base) in order
to generate a full image for a first version (e.g., Version 1) of
Virtual Machine B and the file Dependent_Base3 may comprise a
second dependent base file that includes data differences that may
be applied to a full image of the first version of Virtual Machine
B in order to generate a first version (e.g., Version 1) of Virtual
Machine C. In some cases, the dependent base file Dependent_Base
may be considered a first forward incremental file that depends
from the base image for Virtual Machine A and may be used to
generate the first version of Virtual Machine B and the dependent
base file Dependent_Base3 may be considered a second forward
incremental file that depends from both the base image for Virtual
Machine A and the dependent base file Dependent_Base and may be
used to generate the first version of Virtual Machine C. One
benefit of generating and applying dependent bases either in
parallel (e.g., four dependent virtual machines may each be derived
from a base image file for an independent virtual machine) or in
series (e.g., a first dependent virtual machine may be derived from
an independent virtual machine and a second dependent virtual
machine may be derived from the first dependent virtual machine) is
that the amount of data storage space required to store the
different versions of virtual machines may be reduced and the
deduplication rate may be increased.
[0138] FIG. 6H depicts one embodiment of a merged file for
generating Version 1 of Virtual Machine C using the stored files
depicted in FIG. 6G. The merged file includes a first pointer
(pBase) that references the base image for Virtual Machine A, a
second pointer (pDependent_Base) that references the dependent base
file for Virtual Machine B, and a third pointer (pDependent_Base3)
that references the dependent base file Dependent_Base3 for Virtual
Machine C. In one embodiment, to generate the full image of Version
1 of Virtual Machine C, the base image (Base) for Virtual Machine A
may be acquired, the data changes associated with the dependent
base file Dependent_Base may be applied to the base image to
generate a first intermediate image, and the data changes
associated with the dependent base file Dependent_Base3 may be
applied to the first intermediate image to generate the full image
for Version 1 of Virtual Machine C.
[0139] In a virtualized environment, redundancy in data stored on
two or more different virtual machines may occur due to a common
operation system used by the virtual machines (e.g., 100 virtual
machines within the virtualized environment may run the same
operating system) or due to the cloning of virtual machines within
the virtualized environment. A cloned virtual machine may include
the same operating system and applications as a virtual machine
from which the cloned virtual machine was cloned. In some cases, in
a virtualized environment supporting an enterprise, many of the
virtual machines used by employees of the enterprise may comprise
cloned virtual machines that include a significant amount of
redundancy due to the installation of a common operating system and
common applications (e.g., more than 85% of the data may be
redundant). The commonality between different virtual machines may
allow a virtual machine to be efficiently stored as a dependent
virtual machine that may be derived from an independent virtual
machine. The dependent virtual machine may be associated with a
dependent base file that is stored on the same physical machine as
a base image associated with the independent virtual machine. The
dependent base file and the base image may reside on two different
storage devices within the same physical machine. In some cases, to
reduce the time needed to restore a version of the dependent
virtual machine, the dependent base file and other incremental
files associated with the dependent virtual machine may be stored
in an SSD of the physical machine and the base image associated
with the independent virtual machine may be stored in a HDD of the
physical machine.
[0140] FIG. 6I is a flowchart describing one embodiment of a
process for storing snapshots of a virtual machine. In one
embodiment, the process of FIG. 6I may be performed by a storage
appliance, such as storage appliance 170 in FIG. 1A.
[0141] In step 612, an initial snapshot of a first virtual machine
is acquired. The initial snapshot may be acquired from a
virtualization manager, such as virtualization manager 169 in FIG.
1A. The initial snapshot of the virtual machine may comprise the
first point in time version of the first virtual machine saved to a
storage appliance, such as storage appliance 170 FIG. 1A. The
initial snapshot may include a full image of the first virtual
machine or a full image of one or more virtual disks associated
with the first virtual machine. In some cases, a signature may be
generated for each virtual disk of a virtual machine. In other
cases, a signature may be generated for an entire virtual machine
that includes one or more virtual disks.
[0142] In step 614, a signature for the initial snapshot is
generated. In one example, the signature may include one or more
hash values. In another example, the signature may include a
fixed-length value (e.g., 1 KB or 4 B in size) that is
statistically unique to the full image. The signature may be
generated using a similarity hashing algorithm. One embodiment of a
process for generating a signature of a snapshot is described later
in reference to FIG. 6J.
[0143] In step 616, a second virtual machine is identified based on
the signature. The second virtual machine is associated with a base
image. The second virtual machine may comprise a previously backed
up virtual machine and may be associated with a second signature.
The second virtual machine may be identified based on a comparison
of the signature with the second signature. In one embodiment, the
second virtual machine may comprise the virtual machine out of a
plurality of virtual machines with the closest matching signature
to the signature associated with the initial snapshot of the first
virtual machine. In some cases, a nearest neighbor search may be
performed on a plurality of signatures associated with a plurality
of virtual machines in order to identify the second virtual
machine.
[0144] In step 618, a dependent base file is generated using the
full image and the base image. The dependent base file may be
generated by determining the data differences between the full
image and the base image. The data differences may comprise bit
differences between the full image and the base image that are
determined using a bitwise XOR operation. In one example, the
dependent base file may comprise a forward incremental file that
depends from the base image for the second virtual machine and from
which the full image may be generated. In step 620, a merged file
is generated for the initial snapshot. The merged file may include
a first pointer to the base image and a second pointer to the
dependent base file. In step 622, the merged file and the signature
may be stored in a metadata store, such as distributed metadata
store 110 in FIG. 1C.
[0145] In step 624, the dependent base file is written to a first
storage device of a first type. The dependent base file may be
compressed prior to being written to the first storage device. In
one embodiment, the base image for the second virtual machine may
be located on a first physical machine and the first storage device
may be located on the first physical machine. By locating both the
base image and the dependent base file on the same physical
machine, network traffic may be reduced and the time to restore
versions of the first virtual machine may be reduced.
[0146] In one embodiment, both the base image and the dependent
base file may be located on the first storage device (e.g., an
SSD). In another embodiment, the base image for the second virtual
machine may be stored on a second storage device of a second type
different from the first storage device of the first type. In one
example, the dependent base file may be stored using a flash-based
memory and the base image may be stored using a HDD. In order to
restore the full image, the dependent base file and any other
incremental files may be read from the first storage device of the
first type and, in parallel, the base image may be read from the
second storage device of the second type (e.g., the base image may
be read by performing a sequential read from a HDD).
[0147] FIG. 6J is a flowchart describing one embodiment of a
process for generating a signature of a snapshot. The process
described in FIG. 6J is one example of a process for implementing
step 614 in FIG. 6I. In one embodiment, the process of FIG. 6J may
be performed by a storage appliance, such as storage appliance 170
in FIG. 1A.
[0148] In step 632, one or more blocks within a full image are
determined. The full image may be associated with a snapshot of a
virtual machine. The full image may correspond with a state of a
virtual disk of the virtual machine. In one example, the one or
more blocks may comprise sampled data regions associated with a
portion of the full image. In another example, the one or more
blocks may comprise a set of noncontiguous data regions within the
full image. The set of noncontiguous data regions may include a
first data region that does not border or overlap with a second
data region of the set of noncontiguous data regions. In some
cases, the one or more blocks may be arranged in a manner that
allows a greater number of hash values to be computed near the
beginning or the end of the full image. For example, the one or
more blocks may be arranged such that a percentage (e.g., 80%) of
the one or more blocks are located within a first portion of the
full image (e.g., within the first 2 GB of data). One reason for
the increased sampling or weighting of the first portion of the
full image is that a common operating system may reside in the
first portion of the full image (e.g., the common operating system
may reside in the first 1 GB of the full image).
[0149] In one embodiment, a first set of data blocks (e.g., 100 4
KB data blocks) may be identified within the full image. Each block
of the first set of data blocks may be located within a different
region of the full image compared to the other data blocks. Each
block of the first set of data blocks may correspond with a
different portion of the full image compared with the other data
blocks of the first set of data blocks. In one example, a first
subset of the first set of data blocks (e.g., the first 50 out of
100 data blocks) may be arranged such that a data block of the
first subset is located at the beginning of every 16 MB (or any
other fixed data length) of data in the full image. In the case
that the first subset of data blocks are arranged every 16 MB, then
the offsets for the first subset of data blocks may be at 0, 16 MB,
32 MB, . . . , and 784 MB. In the case that the first subset of
data blocks are arranged every 4 MB, then the offsets for the first
subset of data blocks may be at 0, 4 MB, 8 MB, . . . , and 196 MB.
In one example, a second subset of the first set of data blocks
(e.g., the last 50 out of 100 data blocks) may be arranged such
that the data blocks are positioned at increasingly greater
distances from each other. In this case, the offsets for the second
subset of data blocks may be at 1 GB, 1.1 GB, 1.3 GB, 1.6 GB, 2 GB,
2.5 GB, etc. In another example, a second subset of the first set
of data blocks (e.g., the last 50 out of 100 data blocks) may be
arranged such that the data blocks are positioned at monotonically
increasing distances from each other. In this case, the offsets for
the second subset of data blocks may be at 1 GB, 1.1 GB, 1.2 GB,
1.5 GB, 2 GB, 3 GB, etc.
[0150] In some embodiments, the first set of data blocks identified
within the full image may be arranged such the data blocks of the
first set of data blocks are spaced at monotonically increasing
distances from each other. In other embodiments, the first set of
data blocks may be arranged such that a majority of the first set
of data blocks are located within a first portion of the full image
that is located near or at a beginning or an end of the full image.
In one embodiment, each data block of the first set of data blocks
exists within a first portion of the full image (e.g., only the
first 1.5 GB or other fixed data length of data within the full
image may be sampled).
[0151] In step 634, one or more hash values corresponding with the
one or more blocks are determined. In one embodiment, each of the
one or more hash values may be determined using a hash function,
such as MD5, SHA2-56, or CRC32. In one example, a first hash value
corresponding with a first data block of the one or more blocks may
be computed using a hash function and a second hash value
corresponding with a second data block of the one or more blocks
may be computed using the hash function. In step 636, a signature
is generated based on an ordered list of the one or more hash
values. In one embodiment, if the hash function for generating the
one or more hash values comprises CRC32 and the number of one or
more blocks comprises 100 data blocks, then the signature may
comprise an ordered list of 100 4 B values. To compare a first
signature with a second signature, each hash value in the ordered
list of hash values for the first signature may be compared with a
corresponding hash value in the ordered list of hash values for the
second signature. A matching score may be determined based on the
number of matched hashes divided by the number of total hashes. In
one example, if the number of ordered hash values comprises 100
hash values and the number of matching hash values comprises 70
hash values, then the matching score may comprise 0.7. In this
case, a matching score of 1.0 would indicate that all of the
ordered hash values between a first signature and a second
signature matched. In some cases, if the highest matching score for
a virtual machine is less than a threshold value (e.g., is less
than 0.5), then the virtual machine may be stored as an independent
virtual machine.
[0152] In one embodiment, a plurality of noncontiguous data blocks
within a full image of a virtual machine may be sampled (e.g., 100
4 KB data blocks out of a full image comprising 100 GB) and a
plurality of hash values corresponding with the plurality of
noncontiguous data blocks may be generated. A signature for the
virtual machine may comprise an ordered list of the plurality of
hash values. The plurality of noncontiguous data blocks may be
arranged such that data blocks of a first plurality of the
plurality of noncontiguous data blocks (e.g., the first 30 out of
100 data blocks) are spaced at a fixed distance from each other and
data blocks of a second plurality of the plurality of noncontiguous
data blocks (e.g., the last 70 out of 100 data blocks) are spaced
at monotonically increasing distances from each other. In this
case, each data block of the first plurality may be spaced apart or
separated by a fixed data length (e.g., every 16 MB) and each data
block of the second plurality may be spaced apart or separate by an
increasing data length (e.g., the first two data blocks of the
second plurality may be spaced apart by 0.1 GB and the next two
data blocks of the second plurality may be spaced apart by 0.2 GB).
In some cases, the first plurality of the plurality of
noncontiguous data blocks may be determined based on a size and/or
a location of an operating system within the full image.
[0153] In one embodiment, a size of an operating system or a memory
footprint associated with the operating system may be acquired and
used to identify a first portion of a full image of a virtual
machine (e.g., the first portion of the full image may be located
at the beginning of the full image and correspond with the size of
the operating system, such as the first 0.5 GB of the full image).
In this case, a first set of data blocks may be sampled within the
first portion of the full image and a set of hash values
corresponding with the first set of data blocks may be generated. A
portion of a signature for the virtual machine may comprise an
ordered list of the set of hash values. The first set of data
blocks may be arranged such that the data blocks of the first set
of data blocks are spaced at a fixed distance from each other or
are spaced at monotonically increasing distances from each
other.
[0154] In some embodiments, a dependent virtual machine may depend
from a first independent virtual machine at a first point in time
and then depend from a second independent virtual machine different
from the first independent virtual machine at a second point in
time subsequent to the first point in time. In one example, the
best matching independent virtual machine for the dependent virtual
machine (e.g., the virtual machine with the highest matching score)
at the first point in time may comprise the first independent
virtual machine and the best matching independent virtual machine
for the dependent virtual machine at the second point in time may
comprise the second independent virtual machine. In some cases, the
updating of the independent virtual machine used for deriving a
dependent virtual machine may be performed periodically (e.g.,
every month).
[0155] In some embodiments, a data management system including one
or more storage appliances may store a first set of snapshots of a
virtual machine on a first storage appliance within a first storage
domain (e.g., an on-premise or local storage appliance) and a
second set of snapshots of the virtual machine on a second storage
appliance within a second storage domain (e.g., a remote storage
appliance) or within a cloud-based storage service. In one example,
the first set of snapshots may comprise the 50 most recent
snapshots of the virtual machine and the second set of snapshots
may comprise all the other snapshots of the virtual machine. In
another example, the first set of snapshots may comprise all
snapshots of a virtual machine captured within the past year and
the second set of snapshots may comprise all snapshots of the
virtual machine captured within the past five years. In another
example, a storage appliance, such as storage appliance 170 in FIG.
1A, may manage and store a first set of snapshots comprising all
snapshots of a virtual machine captured within a first period of
time (e.g., within the past three months) and the storage appliance
may push all snapshots of the virtual machine captured within a
second period of time (e.g., within the past ten years) to a remote
storage appliance or a cloud-based storage service. In some cases,
a cloud-based storage service may run an integrated software stack
including a data management system, such as data management system
102 in FIG. 1C, a distributed job scheduler, a distributed metadata
store, and a distributed file system. One benefit of managing and
storing snapshots of one or more virtual machines using a hybrid
local/remote data management system that includes a local storage
appliance and a remote storage appliance and/or a cloud-based
storage service is that the hybrid local/remote data management
system may provide near instantaneous restoration of the snapshots
of the one or more virtual machines while providing
disaster-resistant data protection in the event that the first
storage appliance or the remote storage appliance fails.
[0156] FIG. 7A depicts one embodiment of a first set of stored
files associated with different versions of a Virtual Machine A (VM
A) and a second set of stored files associated with different
versions of a Virtual Machine B (VM B) located within a first
storage domain (Storage Domain A). The first set of stored files
includes a base image associated with Virtual Machine A (Base_A)
and the second set of stored files includes a base image associated
with Virtual Machine B (Base_B). In some cases, the Virtual Machine
B may be associated with a reverse incremental RB1 that is stored
within the first storage domain (e.g., a local storage appliance)
and 728 other reverse incrementals that are stored within a second
storage domain (e.g., within a remote storage appliance or a
cloud-based storage service) different from the first storage
domain. In one example, in order generate a full image for one of
the versions of Virtual Machine B associated with the 728 other
reverse incrementals, one or more of the 728 reverse incrementals
may be transferred to the first storage domain from the second
storage domain and the full image may be generated within the first
storage domain. In this case, the one or more of the 728 reverse
incrementals transferred to the first storage domain may be cached
within the first storage domain for future access to the same data.
In another example, in order generate a full image for one of the
versions of Virtual Machine B associated with the 728 other reverse
incrementals, the full image may be generated within the second
storage domain and then transferred to the first storage
domain.
[0157] FIG. 7B depicts one embodiment of a merged file for
generating Version 732 of Virtual Machine B using the stored files
depicted in FIG. 7A. The merged file includes a first pointer
(pBase_B) that references the base image for Virtual Machine B
(Base_B), a second pointer (pFB1) that references the forward
incremental FB1, and a third pointer (pFB2) that references the
forward incremental FB2. In one embodiment, to generate a full
image for Version 732 of Virtual Machine B, the base image (Base_B)
for Virtual Machine B may be acquired, the data changes associated
with the forward incremental FB1 may be applied to the base image
to generate a first intermediate image, and the data changes
associated with forward incremental FB2 may be applied to the first
intermediate image to generate the full image of Version 732 of
Virtual Machine B.
[0158] FIG. 7C depicts one embodiment of a third set of stored
files associated with different versions of the Virtual Machine A
(VM A) depicted in FIG. 7A and a fourth set of stored files
associated with different versions of the Virtual Machine B (VM B)
depicted in FIG. 7A located within a second storage domain (Storage
Domain B) different from the first storage domain (Storage Domain
A) depicted in FIG. 7A. In some cases, the first storage domain may
communicate with the second storage domain via a network, such as a
wide area network or the Internet. The third set of stored files
includes a base image associated with Virtual Machine A (Base_A)
and the fourth set of stored files includes a dependent base file
associated with Virtual Machine B (Dependent_Base_B). As depicted,
Virtual Machine A is associated with 58 different versions
corresponding with a forward incremental FA1, a base image Base_A,
and 56 reverse incrementals RA1-RA56. Virtual Machine B is
associated with 732 different versions corresponding with a forward
incrementals FB1-FB2, a dependent base file Dependent_Base_B, and
729 reverse incrementals RB1-RB729. In some cases, the second
storage domain may include a remote storage appliance or a
cloud-based storage service.
[0159] FIG. 7D depicts one embodiment of a merged file for
generating Version 732 of Virtual Machine B using the stored files
depicted in FIG. 7C. The merged file includes a first pointer
(pBase_A) that references the base image for Virtual Machine A
(Base_A), a second pointer (pDependent_Base_B) that references the
dependent base file for Virtual Machine B (Dependent_Base_B), a
third pointer (pFB1) that references the forward incremental FB1,
and a fourth pointer (pFB2) that references the forward incremental
FB2. In one embodiment, to generate a full image for Version 732 of
Virtual Machine B, the base image for Virtual Machine A (Base_A)
may be acquired and the data changes associated with the dependent
base file associated with Virtual Machine B (Dependent_Base_B) may
be applied to the base image to generate a first intermediate
image, the data changes associated with forward incremental FB1 may
be applied to the first intermediate image to generate a second
intermediate image, and the data changes associated with forward
incremental FB2 may be applied to the second intermediate image to
generate the full image of Version 732 of Virtual Machine B.
[0160] In one embodiment, the first storage domain in FIG. 7A may
comprise a local storage domain within a local data center and the
second storage domain in FIG. 7C may comprise a remote storage
domain within a remote data center. The files stored within the
local storage domain may be stored using a first storage appliance,
such as storage appliance 170 in FIG. 1A. The files stored in the
remote storage domain may be stored using a second storage
appliance, such as storage appliance 140 in FIG. 1A. In another
embodiment, the first storage domain in FIG. 7A may comprise a
remote storage domain and the second storage domain in FIG. 7C may
comprise a local storage domain.
[0161] In some embodiments, a first storage appliance may determine
whether files stored within the first storage appliance are to be
archived or transferred to a second storage appliance based on a
threshold number of versions. In one example, once a total number
of versions of a virtual machine stored within the first storage
appliance reaches a maximum number of versions, then the oldest
versions of the virtual machine that cause the maximum number of
versions to be exceeded may be transferred to the second storage
appliance or to a cloud-based storage device. In another example,
if a maximum number of versions for a first storage appliance
storing the first set of stored files associated with Virtual
Machine A in FIG. 7A is three, then the 55 versions of Virtual
Machine A that are older than the version associated with reverse
incremental RA1 may be transferred to a second storage appliance,
such as the second storage appliance storing the third set of
stored files in FIG. 7C. The 55 versions of Virtual Machine A
transferred to the second storage appliance may correspond with
reverse incrementals RA2-RB56 in FIG. 7C.
[0162] In some embodiments, a first storage appliance may determine
whether files stored within the first storage appliance are to be
archived or transferred to a second storage appliance based on a
threshold point in time. In one example, once a particular version
of a virtual machine associated with a particular point in time is
older than the threshold point in time (e.g., the particular point
in time is older than three months from a current time), then the
particular version may be transferred to the second storage
appliance or to a cloud-based storage device. In another example,
if 728 versions of Virtual Machine B in FIG. 7A are older than a
threshold point in time (e.g., more than 30 days old or more than
one year old), then the 728 versions of Virtual Machine B may be
transferred to a second storage appliance, such as the second
storage appliance storing the fourth set of stored files in FIG.
7C. The 728 versions of Virtual Machine B transferred to the second
storage appliance may correspond with reverse incrementals
RB2-RB729 in FIG. 7C.
[0163] In some embodiments, in order to minimize network
congestion, data associated with virtual machine snapshots may be
deduplicated and/or compressed prior to being transferred from a
first storage domain to a second storage domain. In one example, a
dependent base file or a base image may be compressed using a
lossless data compression algorithm such as LZ4 or LZ77 prior to
being transferred to the second storage domain.
[0164] In some embodiments, rather than transferring a base image
associated with a virtual machine from a first storage domain to a
second storage domain, a dependent base file that derives from
another base image within the second storage domain may be
transferred instead. In one example, rather than transferring the
base image associated with Virtual Machine B (Base_B) in FIG. 7A to
the second storage domain, a dependent base file (Dependent_Base_B)
may be generated in the first storage domain and transferred to the
second storage domain if the base image associated with Virtual
Machine A (Base_A) from which the dependent base file depends
exists within the second storage domain. In some cases, a first
storage appliance within the first storage domain may identify a
base image from which a dependent base file may be derived by
acquiring a list of independent virtual machines within the second
storage domain, determining a matching signature score (e.g.,
determined based on a number of matched hashes) for each
independent virtual machine on the list of independent virtual
machines that exists within the first storage domain, and
identifying the independent virtual machine stored within the first
storage domain with the highest matching signature score. In one
embodiment, a dependent base file associated with a virtual machine
may be transferred in place of a base image for the virtual machine
based on a classification of the virtual machine. For example, if
the virtual machine is classified as a gold-level virtual machine,
then the base image may be transferred to the second storage
domain. However, if the virtual machine is classified as a
bronze-level virtual machine, then the dependent base file may be
transferred to the second storage domain.
[0165] FIG. 7E is a flowchart describing one embodiment of a
process for managing snapshots of a virtual machine using a hybrid
local/remote data management system. In one embodiment, the process
of FIG. 7E may be performed by a storage appliance, such as storage
appliance 170 in FIG. 1A.
[0166] In step 712, an initial snapshot of a first virtual machine
is acquired. The initial snapshot may be acquired from a
virtualization manager, such as virtualization manager 169 in FIG.
1A. The initial snapshot of the virtual machine may comprise the
first point in time version of the first virtual machine saved to a
storage appliance, such as storage appliance 170 FIG. 1A. The
initial snapshot may include a full image of the first virtual
machine or a full image of one or more virtual disks associated
with the first virtual machine. In one embodiment, a signature may
be generated from the full image associated with the initial
snapshot in order to identify a candidate base image associated
with a second virtual machine. In one example, a signature may be
generated for the entire first virtual machine or for a first
virtual disk of the first virtual machine in order to identify the
candidate base image.
[0167] In step 714, a full image associated with the initial
snapshot is stored within a first storage domain. The full image
may be stored using a local storage appliance within the first
storage domain. In step 716, one or more snapshots of the first
virtual machine are acquired subsequent to acquiring the initial
snapshot. In one example, the initial snapshot of the first virtual
machine may comprise a first version of the first virtual machine
and the one or more snapshots of the first virtual machine may
comprise one or more subsequent versions of the first virtual
machine. In step 718, one or more incremental files associated with
the one or more snapshots are stored within the first storage
domain. The one or more incremental files may be stored using the
local storage appliance within the first storage domain. The one or
more incremental files may include one or more forward incremental
files and/or one or more reverse incremental files.
[0168] In step 720, a base image associated with a second virtual
machine different from the first virtual machine is identified. The
second virtual machine may comprise a virtual machine that is
stored within the first storage domain and that is stored within a
second storage domain with the highest matching signature score or
the most data similarity with the full image stored within the
first storage domain. In step 722, a dependent base file is
generated using the full image and the base image. In step 724, the
dependent base file is transferred to a second storage domain. In
one embodiment, the second storage domain may comprise a remote
storage appliance. In another embodiment, the second storage domain
may comprise a cloud-based storage service.
[0169] In step 726, a maximum number of snapshots and a maximum age
for snapshots are acquired. In one example, the maximum number of
snapshots may impose a limit to the number of versions of the first
virtual machine that may be stored within the first storage domain.
In another example, the maximum age for snapshots may impose a
limit on the number of versions of the first virtual machine that
may be stored within the first storage domain. In step 728, it is
determined that the one or more incremental files associated with
the one or more snapshots should be transferred to the second
storage domain based on the maximum number of snapshots and/or the
maximum age for snapshots. In step 730, the one or more incremental
files are transferred to the second storage domain. In some cases,
after the one or more incremental files have been transferred to
the second storage domain, the one or more incremental files may be
deleted from the first storage domain to free-up storage space
within the first storage domain.
[0170] In some cases, one or more snapshots of the first virtual
machine may be transferred to the second storage domain upon
detection that the first storage domain stores more than a
threshold number of snapshots for the first virtual machine. In
other cases, every snapshot of the first virtual machine that is
stored within the first storage domain may be automatically
transferred to the second storage domain. The snapshots of the
first virtual machine may be directly accessed via the first
storage domain or the second storage domain. In response to a
request from the first storage domain, the second storage domain
may transfer a snapshot of the first virtual machine to the first
storage domain (e.g., a snapshot that was originally transferred
from the first storage domain to the second storage domain may be
transferred back to the first storage domain).
[0171] In one embodiment, a hybrid local/remote data management
system may include a remote replication system that replicates data
between a local storage appliance and a remote storage appliance
and/or a cloud-based storage service in real-time. The replicated
data may be deduplicated and compressed prior to being transferred
between the local storage appliance and the remote storage
appliance or the cloud-based storage service. The hybrid
local/remote data management system may include a hybrid data
management system that manages snapshots of one or more virtual
machines across a local storage appliance and a remote storage
appliance and/or a cloud-based storage service in real-time. The
hybrid data management system may dynamically move data associated
with the snapshots based on user configured parameters such as a
maximum number of snapshots that may be stored on the local storage
appliance, a maximum number of snapshots that may be stored on the
remote storage appliance, a maximum age for the snapshots stored on
the local storage appliance, and a maximum age for the snapshots
stored on the remote storage appliance. In some cases, the hybrid
data management system may cause a first set of snapshots for the
one or more virtual machines to be stored on the local storage
appliance, a second set of snapshots for the one or more virtual
machines to be stored on the remote storage appliance, and a third
set of snapshots for the one or more virtual machines to be stored
on both the local storage appliance and the remote storage
appliance (e.g., the third set of snapshots may comprise replicated
snapshots).
[0172] In some embodiments, deduplicated data corresponding with
one or more snapshots of a virtual machine may be transferred from
the cloud or a cloud-based storage device to a storage appliance,
such as storage appliance 170 in FIG. 1C, in order to rehydrate the
storage appliance. In some cases, the reassembly of data from
deduplicated data may be referred to as data rehydration. In some
cases, cloud data associated with a virtual machine may be
self-sufficient and used to rehydrate a storage appliance.
[0173] In one embodiment, a virtualized environment cloning
application may be used to create a cloned environment of a set of
virtualized production services running on a plurality of virtual
machines within a production environment. The virtualized
environment cloning application may comprise a software-level
component of a storage appliance or an application running on a
storage appliance, such as storage appliance 170 in FIG. 1C. The
virtualized environment cloning application may generate the cloned
environment to enable the testing of new features within the cloned
environment or for experimental or analytical purposes. The cloned
environment may include a plurality of cloned virtual machines that
are derived from snapshots of the plurality of virtual machines
within the production environment at a particular point in time. In
one example, the cloned environment may comprise a virtual
laboratory of networked virtual machines in which applications may
be tested without interfering with the production environment.
[0174] The set of virtualized production services may include a
first service (e.g., a database service) and a second service that
depends on the first service (e.g., an inventory management
application that depends on the database service). The first
service may be run using a first virtual machine of the plurality
of virtual machines and the second service may be run using a
second virtual machine of the plurality of virtual machines. In
some cases, upon a selection of the second service for cloning
(e.g., via a GUI selection by an end user of a storage appliance),
other services on which the second service relies, such as the
first service, may be automatically identified due to dependencies
with the second service. The dependencies may be identified via a
dependency mapping table stored within a distributed metadata
store, such as distributed metadata store 110 in FIG. 1C. Once the
set of virtualized production services have been identified, each
of the set of virtualized production services may be paused or
quiesced while snapshots of the plurality of virtual machines
running the set of virtualized production services are captured.
While the set of virtualized production services are paused, a
virtualization interface, such as virtualization interface 104 in
FIG. 1C, may be used to acquire the snapshots of the plurality of
virtual machines. Once the snapshots of the plurality of virtual
machines have been acquired, then cloned versions of the plurality
of virtual machines may be generated and stored using a distributed
file system, such as distributed file system 112 in FIG. 1C.
[0175] In cases where the cloned versions of the plurality of
virtual machines must be configured with the same IP addresses as
the plurality of virtual machines within the production environment
(e.g., due to the inability of a backup system to modify an
application specific configuration that includes an IP address),
the cloned environment may have to be brought up in a private
network to prevent conflicts with the plurality of virtual machines
within the production environment. In one embodiment, a gateway
virtual machine may be configured to act as a gateway between the
cloned environment and an outside network. All requests to IP
addresses that are not part of the cloned environment may be routed
through the gateway virtual machine to the outside network. The
gateway may act as a Network Address Translation (NAT) layer for
external clients that want to connect to the cloned environment
from the outside network. Each of the virtualized production
services within the cloned environment may be exposed through
separate IP addresses to the outside network and requests may be
routed to the appropriate virtualize production service by the NAT
layer.
[0176] In some cases, runbook automation techniques or other
workflow automation techniques may be used to generate and bring up
the cloned versions of the plurality of virtual machines in an
appropriate order such that a cloned virtual machine is not brought
up until dependent virtual machines have been brought up and the
applications running on the dependent virtual machines are running.
The appropriate order may be specified using a configuration file
that may be created and/or be modified by a system administrator or
a virtualization administrator prior to generation of the cloned
versions. In one example, in the case of a web server that relies
on a database to display a web site, the database may be
automatically brought up first in the cloned environment before the
web server is brought up since the web server may experience errors
if it is not able to access the database.
[0177] FIG. 8 is a flowchart describing one embodiment of a process
for automating the generation of a cloned virtual machine
environment. In one embodiment, the process of FIG. 8 may be
performed by a storage appliance, such as storage appliance 170 in
FIG. 1A.
[0178] In step 802, an application running on a first virtual
machine is identified. The application may be identified by an end
user of a storage appliance using a graphical user interface. The
application may comprise an application to be cloned. The
application may comprise one application of a plurality of
applications running on the first virtual machine in which the
first virtual machine is to be cloned. The first virtual machine
may comprise one virtual machine out of a plurality of virtual
machines that are to be cloned in order to run, for example, a set
of virtualized production services within a cloned environment. In
step 804, a first snapshot of the first virtual machine is
acquired. The first snapshot may correspond with a state of the
first virtual machine at a particular point in time. In step 806, a
set of dependent applications that the application depends on for
operation is determined. In one example, the application may
comprise an inventory management application that depends on a
database application (e.g., the inventory management application
may use the database application in order to access or store
inventory-related information). In this case, the inventory
management application may run on the first virtual machine and the
database application may run on a different virtual machine that is
in communication with the first virtual machine.
[0179] In step 808, an ordering of the set of dependent
applications is determined such that every application that a
particular application of the set of dependent applications depends
on precedes the particular application in the ordering. In one
example, the application may depend on a second application, which
in turn depends on a third application. In this case, the ordering
may comprise the third application followed by the second
application followed by the application. The dependencies between
each application of the set of dependent applications may be
determined using a dependency mapping table or using a direct
acyclic graph (DAG) in which vertices of the DAG correspond with
the applications of the set of dependent applications and directed
edges between the vertices may correspond with the dependencies. In
one example, a directed edge from a predecessor node to a successor
node may represent that the successor node depends on the
predecessor node.
[0180] In step 810, a set of virtual machines that run the set of
dependent applications is determined. The set of virtual machines
may correspondence with virtual machines running the set of
dependent applications at the particular point in time. In step
812, a set of snapshots of the set of virtual machines is acquired.
The set of snapshots may correspond with states of the set of
virtual machines at the particular point in time. In some cases,
the set of virtual machines may be paused or quiesced while the set
of snapshots are captured.
[0181] In step 814, a second set of virtual machines is brought up
using the set of snapshots. Each virtual machine of the second set
of virtual machines is brought up in an order that satisfies the
ordering of the set of dependent applications. The second set of
virtual machines may comprise cloned versions of the set of virtual
machines that run the set of dependent applications. In step 816, a
second virtual machine is brought up using the first snapshot of
the first virtual machine subsequent to bringing up the second set
of virtual machines. The second virtual machine may comprise a
cloned version of the first virtual machine. In some embodiments,
where the cloned versions of the first virtual machine and the set
of virtual machines must be configured with the same IP addresses
as the first virtual machine and the set of virtual machines, the
cloned versions may be brought up in a private network and a
gateway virtual machine may be configured to act as a gateway
between the cloned versions within the private network and outside
networks.
[0182] FIG. 9 is a flowchart describing one embodiment of a process
for operating a cluster-based file server that does not require a
front-end load balancer. In one embodiment, the process of FIG. 9
may be performed by a storage appliance, such as storage appliance
170 in FIG. 1A.
[0183] In step 902, a first floating IP address is assigned to a
first node in a cluster. The first node may respond to requests
made to the first floating IP address. The cluster may comprise a
plurality of physical machines. Each physical machine of the
plurality of physical machines may correspond with a node in the
cluster. The cluster may comprise a cluster-based network file
server. In one embodiment, a hypervisor in communication with the
cluster may be configured with the first floating IP address. In
some cases, the hypervisor may not provide a failover mechanism nor
be able to update or reconfigure the first floating IP address
after the hypervisor has been configured with the first floating IP
address.
[0184] In step 904, a second floating IP address is assigned to a
second node in the cluster. The first floating IP address is
different from the second floating IP address. The second node may
respond to requests made to the second floating IP address. In step
906, it is detected that the first node has failed. In one example,
the first node may become nonresponsive to communications over the
network due to a hardware failure or a network failure. In one
embodiment, a cluster management system may periodically monitor
the availability of nodes within the cluster and flag a node
failure when a particular node within the cluster goes down or
becomes nonresponsive after a threshold period of time (e.g., a
node has been nonresponsive for more than thirty seconds or two
minutes). In step 908, a set of nodes within the cluster that are
responsive is determined. The set of nodes may comprise the nodes
within the cluster that are responsive or announcing themselves as
alive over a network connecting the cluster. The set of nodes may
be determined in response to detecting that the first node has
failed.
[0185] In step 910, a set of priority values corresponding with the
set of nodes is generated. In one embodiment, given a number (N) of
nodes in a cluster from node(0) to node(N-1), for a floating IP
address (i), the priority value of node(j) may be assigned (j-i)
modulo N. In one example, node(j) may assume floating IP address
(i) only if its priority value is greater than that of any other
node in the cluster that is alive and announcing itself on the
network. In another embodiment, given a number (N) of nodes in a
cluster from node(0) to node(N-1), for a floating IP address (i),
the priority value of node(j) may be (i-j) modulo N. In one
example, node(j) may assume floating IP address (i) only if its
priority value is less than that of any other node in the cluster
that is alive and announcing itself on the network. In step 912, it
is determined that the second node is associated with a highest
priority value of the set of priority values. In step 914, the
first floating IP address is assigned to the second node in
response to determining that the second node is associated with the
highest priority value. In one embodiment, after the first floating
IP address has been assigned to the second node, the second node
may be responsive to and communicate with a hypervisor that is
configured to communicate with the cluster using the first floating
IP address. In other embodiments, it may be determined that the
second node is associated with a lowest priority value of the set
of priority values and the first floating IP address may be
assigned to the second node in response to determining that the
second node is associated with the lowest priority value.
[0186] In some embodiments, it may be determined that the second
node should be assigned the first floating IP address based on a
set of virtual machines that were running on the first node when
the first node failed. Upon detection that the first node has
failed, a set of virtual machines that were running on the first
node when the first node failed may be identified, a subset of the
set of nodes within the cluster that are running the set of virtual
machines may be identified, and a subset of the set of priority
values corresponding with the subset of the set of nodes may be
determined. The second node may then be determined based on a
highest priority value of the subset of the set of priority values.
In one example, the first node may have been running three virtual
machines when the first node failed. The subset of the set of nodes
may comprise nodes within the cluster that are currently running
the three virtual machines. In some cases, the subset of the set of
nodes may comprise nodes within the cluster that are currently
running at least two of the three virtual machines. The subset of
the set of priority values may correspond with priority values
generated for the subset of the set of nodes. The second node may
then be identified as the node within the subset of the set of
nodes with the highest priority value of the subset of the set of
priority values. In another example, if a virtual machine's data
resides on nodes 1, 4, and 6 in a cluster and node 1 fails, then
nodes 4 and 6 may be given a higher priority and either node 4 or
node 6 may be assigned the floating IP address associated with node
1. Upon detection that the first node is back up, the second node
may release the first floating IP address.
[0187] The disclosed technology may be described in the context of
computer-executable instructions, such as software or program
modules, being executed by a computer or processor. The
computer-executable instructions may comprise portions of computer
program code, routines, programs, objects, software components,
data structures, or other types of computer-related structures that
may be used to perform processes using a computer. In some cases,
hardware or combinations of hardware and software may be
substituted for software or used in place of software.
[0188] Computer program code used for implementing various
operations or aspects of the disclosed technology may be developed
using one or more programming languages, including an object
oriented programming language such as Java or C++, a procedural
programming language such as the "C" programming language or Visual
Basic, or a dynamic programming language such as Python or
JavaScript. In some cases, computer program code or machine-level
instructions derived from the computer program code may execute
entirely on an end user's computer, partly on an end user's
computer, partly on an end user's computer and partly on a remote
computer, or entirely on a remote computer or server.
[0189] For purposes of this document, it should be noted that the
dimensions of the various features depicted in the Figures may not
necessarily be drawn to scale.
[0190] For purposes of this document, reference in the
specification to "an embodiment," "one embodiment," "some
embodiments," or "another embodiment" may be used to describe
different embodiments and do not necessarily refer to the same
embodiment.
[0191] For purposes of this document, a connection may be a direct
connection or an indirect connection (e.g., via another part). In
some cases, when an element is referred to as being connected or
coupled to another element, the element may be directly connected
to the other element or indirectly connected to the other element
via intervening elements. When an element is referred to as being
directly connected to another element, then there are no
intervening elements between the element and the other element.
[0192] For purposes of this document, the term "based on" may be
read as "based at least in part on."
[0193] For purposes of this document, without additional context,
use of numerical terms such as a "first" object, a "second" object,
and a "third" object may not imply an ordering of objects, but may
instead be used for identification purposes to identify different
objects.
[0194] For purposes of this document, the term "set" of objects may
refer to a "set" of one or more of the objects.
[0195] Although the subject matter has been described in language
specific to structural features and/or methodological acts, it is
to be understood that the subject matter defined in the appended
claims is not necessarily limited to the specific features or acts
described above. Rather, the specific features and acts described
above are disclosed as example forms of implementing the
claims.
* * * * *