U.S. patent application number 10/832466 was filed with the patent office on 2004-12-02 for method and apparatus for use in data transfer.
This patent application is currently assigned to HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P.. Invention is credited to Evans, Rhys Wyn.
Application Number | 20040240097 10/832466 |
Document ID | / |
Family ID | 33155740 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040240097 |
Kind Code |
A1 |
Evans, Rhys Wyn |
December 2, 2004 |
Method and apparatus for use in data transfer
Abstract
Apparatus for use in transferring data to or from a plurality of
storage media, comprises means for identifying a most recently
written to data storage media of said plurality of data storage
media.
Inventors: |
Evans, Rhys Wyn; (Caerdydd,
GB) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Assignee: |
HEWLETT-PACKARD DEVELOPMENT
COMPANY, L.P.
Houston
TX
|
Family ID: |
33155740 |
Appl. No.: |
10/832466 |
Filed: |
April 27, 2004 |
Current U.S.
Class: |
360/69 ;
G9B/15.153 |
Current CPC
Class: |
G11B 15/689 20130101;
G06F 11/1458 20130101 |
Class at
Publication: |
360/069 |
International
Class: |
G11B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2003 |
GB |
0309546.0 |
Claims
1. Apparatus for use in transferring data to and/or from a
plurality of storage media, comprising: identification apparatus
operable to identify a most recently written to data storage media
of said plurality of data storage media.
2. Apparatus as claimed in claim 1, further comprising: locating
apparatus operable to locate a position in said apparatus of said
most recently written to data storage media.
3. Apparatus as claimed in claim 1, further comprising: acquisition
apparatus operable to acquire said most recently written to data
storage media.
4. Apparatus as claimed in claim 1, further comprising: loading
apparatus operable to load said most recently written data storage
media.
5. Apparatus as claimed in claim 1, further comprising: a
read/write device for reading from and writing to at least one data
storage media.
6. Apparatus as claimed in claim 1, configured for storing said
plurality of storage media.
7. Apparatus as claimed in claim 1, wherein said identification
apparatus comprises; a memory device configured for storing data
relating to each of said plurality of data storage media.
8. Apparatus as claimed in claim 7, wherein said memory device
comprises a non-volatile memory device.
9. Apparatus as claimed in claim 7, wherein said memory device is
configured for providing data fields selected from the following
set: a data field for storing locations of said plurality of data
storage media within said apparatus; a data field for storing, for
each said data storage media, a data describing a chronological
order in which said data storage media was last written to,
relative to at least one other said data storage media.
10. Apparatus as claimed in claim 1, comprising: a user interface,
said user interface operable for displaying a list of computer
entities for which data has been recorded by said data storage
unit.
11. Apparatus as claimed in claim 1, further comprising: a user
interface, said user interface operable for displaying a list of
said plurality of data storage media, and for each said data
storage media, displaying a relative order in which said data
storage media was last written to by the apparatus, relative to
other ones of said plurality of data storage media.
12. A data storage device comprising: a plurality of physical
locations for receiving a plurality of data storage media
cartridges; and a non-volatile memory operable to store data for
distinguishing between said plurality of data storage media
cartridges in said plurality of physical locations.
13. The data storage device as claimed in claim 12, further
comprising: a transport device for transporting said data storage
media cartridges between said plurality of locations.
14 The data storage device as claimed in claim 12, in which: said
data storage device is operable to: store data for use in
recovering each said data storage media cartridge; store data for
identifying each said data storage media cartridge; and store data
relating to a last time at which each said data storage media
cartridge was written to by said data storage device.
15. The data storage device as claimed in claim 12, operable to:
store data relating to each of said plurality of data storage media
cartridges, said data comprising, for each said data storage media
cartridge; data relating to a location of said data storage media
cartridge; and data relating to a date at which said data storage
media cartridge was last written to.
16. The data storage device as claimed in claim 12, comprising: a
user interface, said user interface configured for displaying a
list of computer entities for which data has been recorded by said
data storage device.
17. The data storage device as claimed in claim 12, further
comprising: a user interface, said user interface operable for
displaying a list of said plurality of data storage media
cartridges, and for each said data storage media cartridge, a
relative time at which said data storage media cartridge was last
written to.
18. The data storage device as claimed in claim 12, operable to
carry out a restore operation by automatically selecting a last
used said data storage media cartridge.
19. A data storage device comprising: a cartridge storage device
having a plurality of locations, each said location capable of
storing a data storage media cartridge; a data storage media drive
unit for reading from and writing to a plurality of data storage
media cartridges; an automatic loader device for loading said data
storage media cartridges between said drive unit and said plurality
of locations; and a controller for controlling said media drive
unit and said automatic-loader device; wherein, said data storage
device is operable to identify a most recently written to data
storage media cartridge, and said controller devices controls said
automatic loader device for loading said most recently written to
data storage media cartridge into said data storage media drive
unit.
20. The data storage device as claimed in claim 19, comprising: a
memory for storing data identifying individual ones of said data
storage media cartridges; and a component for identifying relative
times at which individual ones of said data storage media
cartridges were last written to.
21. The data storage device as claimed in claim 19, wherein said
user interface is operable to provide a menu display listing a
plurality of computer entities for which data has been recorded by
said data storage device.
22. The data storage device as claimed in claim 19, wherein said
user interface is operable for providing a menu display comprising
a list of said plurality of data storage media cartridges.
23. The data storage device as claimed in any claim 19, wherein
said user interface is operable for activating an automatic
selection of a data storage media cartridge, which is most recently
written to.
24. The data storage device as claimed in claim 19, wherein said
user interface is operable for browsing a list of said plurality of
data storage media cartridges, and for enabling a user to select a
data storage media cartridge from said list.
25. A method for automatically recording data for use in recovery
of user data of a computer entity, in an automated data storage
unit capable of containing a plurality of individual data storage
media at once, said method comprising: storing said data for use in
recovering user data to a data storage medium; and recording data
relating to said data storage medium on which said recovery data is
stored on.
26. The method as claimed in claim 25, wherein said step of
recording data relating to said data storage medium comprises
recording data relating to a location of said data storage
medium.
27. The method as claimed in claim 25, further comprising:
recording in a non-volatile memory, a relative time data relating
to a time at which said data storage medium was last written to
relative to other data storage media.
28. An automatic operating system recovery method for automatically
recovering an operating system of a computer entity, said method
comprising: maintaining a data storage medium in an automated data
storage unit comprising a plurality of data storage media, said
data storage medium holding data relating to said operating system;
and said automated data storage unit recording data relating to a
location of said data storage medium on which said operating system
recovery data is stored on; automatically locating said stored data
storage medium amongst said plurality of data storage media; and
automatically reading from said located data storage medium said
recovery data.
29. A method of operating a data storage unit comprising a media
cartridge drive unit, and containing a plurality of data storage
media cartridges, for providing a bootable image to a computer
entity, said method comprising: maintaining a list of a plurality
of data storage media cartridges; searching said list of data
storage media cartridges; identifying a latest written to data
storage media cartridge; ensuring that said identified latest
written to data storage media cartridge is placed within said drive
unit comprising said data storage unit; and setting said drive unit
to a mode in which said drive unit emulates a compact disk
reader.
30. The method as claimed in claim 29, wherein said step of
ensuring said drive unit contains a latest written to data storage
media comprises: identifying a location of said data storage media
cartridge; if said identified location is not a location in said
drive unit, physically transferring said data storage media
cartridge from said location to said drive unit.
31. The method as claimed in claim 29, further comprising:
displaying a list of said plurality of data storage media
cartridges, said list identifying; each of said plurality of data
storage media cartridges; for each of said data storage media
cartridges, a latest time at which said data storage media
cartridge was last written to.
32. The method as claimed in claim 30, further comprising:
displaying a list of data storage media cartridges, in a form which
identifies an order in which said plurality of data storage media
cartridges were written to.
33. A method for automatically providing recovery data for enabling
a computer entity to achieve a bootable condition, said recovery
data stored on a data storage medium of a plurality of data storage
media within an automated data storage unit, said method
comprising: storing said recovery data to a data storage medium,
said recovery data comprising: data relating to an operating system
of said computer entity; data relating to a configuration of said
operating system; data relating to a configuration of said computer
entity; application data; and user data; recording a location of
said data storage medium within a plurality of locations; receiving
a signal for recovery of said data; in response to said signal,
selecting said data storage medium storing said latest recovery
data, from a plurality of data storage media; and making available
said latest recovery data in CD format.
34. Program data on a carrier, comprising program code having: a
database component capable of storing a list of a plurality of data
storage media and data relating to each of said data storage media;
a recovery algorithm for controlling a data recovery operation of a
computer entity; and a search algorithm for searching said database
to find a latest written to data storage media.
35 A controller device for controlling a data storage unit, said
data storage unit comprising an automatic loader device; a
read/write device for reading to and writing from said data storage
media, said controller comprising: a non-volatile memory configured
to store a data base to contain data relating to data storage media
in a plurality of locations of said data storage unit; a search
component for automatically finding a location of a most recently
written said data storage medium; and a control component for
controlling an autoloader device to load said located data storage
medium into said read/write device, in order to make available data
of said most recently written to data storage medium.
36. Computer program instructions on a data storage carrier, said
instructions for controlling a data storage unit, said data storage
unit comprising an automatic loader device; a read/write device for
reading to and writing from said data storage media, said program
instructions comprising: a data base component for containing data
relating to data storage media in a plurality of locations of said
data storage unit; a search component for automatically finding a
location of a most recently written said data storage medium; and a
control component for controlling an autoloader device to load said
located data storage medium into said read/write device, in order
to make available data of said most recently written to data
storage medium.
37. A library device capable of holding a plurality of storage
media, comprising: an automatic media identifying component for
identifying a most recently written to data storage media of said
plurality of data storage media.
38. An automated data storage unit for recording a data for use in
recovery of user data of a computer entity, said automated data
storage unit capable of containing a plurality of individual data
storage media at once, said unit comprising: means for storing said
data for use in recovering user data to a data storage medium; and
means for recording data relating to said data storage medium on
which said recovery data is stored on.
39. Apparatus for use in transferring data to and/or from a
plurality of storage media, comprising: means for identifying a
most recently written to data storage media of said plurality of
storage media.
40. Apparatus as claimed in claim 39, further comprising: means for
locating a position in said apparatus of said most recently written
to data storage media.
41. Apparatus as claimed in claim 39, further comprising: means for
acquiring said most recently written to data storage media.
42. Apparatus as claimed in claim 39, further comprising: means for
loading said most recently written data storage media.
43. Apparatus as claimed in claim 39, further comprising: a
read/write device for reading from and writing to at least one data
storage media.
44. Apparatus as claimed in claim 39, configured for storing said
plurality of storage media.
45. Apparatus as claimed in claim 39, wherein said means for
identifying comprises; a memory device configured for storing data
relating to each of said plurality of data storage media.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of computing, and
particularly, although not exclusively, to a method and apparatus
for use in data transfer.
BACKGROUND TO THE INVENTION
[0002] Conventional computer entities have an operating system,
applications, configuration data and user data stored for example
on a direct or network attached storage device such as a hard disk
drive component of the computer entity. Occasionally, catastrophic
failure of a storage device may occur, in which case, an operating
system, all applications, user data, and configuration of the
computer entity are potentially lost.
[0003] It is known in the prior art to provide a `one button
disaster recovery` system, in which an operating system,
applications, configuration data and user data are stored on a back
up data storage device, for example a tape data storage medium, as
a routine back up procedure. Under conditions of catastrophic
failure of a hard disk data storage device of a computer entity, an
operating system, applications, configuration settings and user
data can be recovered from the external data storage medium, and
loaded onto a new replacement hard disk data storage device. This
known system is easy to use. Its activation generally requires a
user to repair the hard disk data storage device of the computer
entity, load the tape data storage medium containing the most
recently recorded back up data into a drive unit, activate a single
control button, and the computer entity automatically loads the
operating system, applications, configuration settings and user
data from the back up tape data storage medium, to reconfigure the
new hard disk data storage device to a data state and configuration
state which the computer entity held at the time of the last back
up operation.
[0004] The prior art one button disaster recovery system based upon
loading configuration data, applications and user data on a single
data storage medium is very successful. However, for computer
installations where unattended automated data recovery is required,
it is known to store data on more than one individual data storage
medium in a known data storage unit. These data storage units are
known as `autoloaders`, or `libraries`. An autoloader/library may
be used for unattended backup, where for example a different tape
data storage cartridge is used each day with the selection of
cartridges being under the control of the backup software. Several
prior art data storage products are available which utilize a
plurality of tape data storage cartridges in a single data storage
unit. For example, a known high capacity back up solution may
comprise a carousel of eight individual tape data storage
cartridges in a single data storage unit.
[0005] Referring to FIG. 1 herein, there is illustrated
schematically a prior art data storage unit capable of storing data
to eight tape data storage cartridges, each having an uncompressed
data storage capacity of 100 Gbytes. The data storage unit
comprises a casing 100, having an entry port 101 for inserting and
extracting tape data storage cartridges; a display and user
interface 102, in a form of a liquid crystal display and a set of
switches 103 for enabling a user to insert and extract tape data
storage cartridges; a host interface bus, including a SCSI port or
a fibre channel (FC) interface; a tape drive unit having read and
write head, a tape transport mechanism, and a tape control
mechanism for reading data from tape and writing data to tapes; an
automatic loader device for loading individual tapes into and out
of the tape drive unit; and a carrousel transport mechanism
carrying a plurality of tape data storage cartridges within the
casing, the loader unit capable of loading a tape data storage
cartridge from the carrousel into the tape drive unit and vice
versa.
[0006] Referring to FIG. 2 herein, there is shown schematically the
data storage device of FIG. 1 in cut away view from above. A
plurality of tape data storage devices 200-207 are carried on the
carrousel 208 around the tape drive unit 209. A loader device 210
loads an individual tape data storage cassette 204 from the
carrousel to the drive, and vice versa from the drive to the
carrousel, under automatic control. Tape cartridges which are not
in the tape drive unit, are stored on the carrousel within the
casing.
[0007] With the prior art multi cartridge storage system, a
plurality of tape data storage cartridges can be stored within a
single data storage unit, thereby giving a high capacity data
storage unit, and unattended data backup, typically using 1 tape
data storage cartridge per day.
[0008] Using such data storage units, each day or more than once a
day, a back up operation of a host computer will be performed. A
different cartridge is used for each back up operation, and so
typically there will be at least one tape data storage cartridge
used for each day's back up. In some cases, back ups may be done
twice per day, once in the morning and once in the afternoon. In
other instances, back ups may be done at more regular intervals
e.g. every hour.
[0009] The data storage unit shown in FIG. 1 is only one example of
a prior art data storage unit, in this case, capable of containing
eight known tape cartridges. However, much larger data storage
units are available, containing more than 200 tape data storage
cartridges. These devices are commonly known as `library` units. In
such library units, a plurality of tape cartridges are stacked in
columns in a rack, and a robotic arm selects a tape cartridge from
a physical column location, and delivers it into a tape drive unit
for reading and writing, and once a read/write operation is
performed, the robotic arm returns the tape cartridge back to its
column location.
[0010] In a disaster recovery situation, where a hard disk drive
unit of a computer entity is damaged beyond repair, using the prior
art `one button disaster recovery` system, after having replaced
the damaged hard disk drive, or set of drives, the user selects the
last back up tape cartridge to be created, inserts that back up
tape cartridge into a tape drive unit associated with the computer
entity, and reconfigures the new hard disk, and installation of
data commences from the back up tape data storage cartridge. The
tape drive unit is placed in a CD emulation mode, and the computer
entity is power cycled, reading data from the tape data storage
cartridge via the tape drive unit.
[0011] In a situation where a user is using more than one tape data
storage cartridge for back up purposes and with a tape drive unit
which only holds one tape cartridge at a time, the user must know
which was the latest back up tape to be created. Since the
operating system on the failed computer will not be up and running,
there is no way of telling the last time or date on which the tape
data storage cartridge was last written to, without the use of a
different computer, or manually recording using an external means
each time a backup is made. Typically, the user will have a pile of
back up tapes, and unless the user has been careful to make good
records, she will not know which tape to insert into the computers
tape drive.
[0012] Where the computer entity is backed up to a data storage
unit having multiple tape cartridges, there is a similar problem,
that the user does not know which cartridge to select to initiate
the disaster recovery. Selecting the wrong tape data storage
cartridge causes recovery of the computer into a state which was
not the most recent state before the disaster occurred.
SUMMARY OF THE INVENTION
[0013] According to a first aspect of the present invention, there
is provided an apparatus for use in transferring data to and/or
from a plurality of storage media, comprising:
[0014] identification apparatus operable to identify a most
recently written to data storage media of said plurality of data
storage media.
[0015] Other aspects are as recited in the claims herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] For a better understanding of the invention and to show how
the same may be carried into effect, there will now be described by
way of example only, specific embodiments, methods and processes
with reference to the accompanying drawings in which:
[0017] FIG. 1 illustrates schematically a known data storage device
having a plurality of tape data storage cartridges;
[0018] FIG. 2 illustrates schematically components of the known
data storage device of FIG. 1;
[0019] FIG. 3 illustrates schematically a host computer entity, and
a data storage unit operable according to specific
implementation;
[0020] FIG. 4 illustrates schematically components of a computer
program comprising a controller of said data storage unit;
[0021] FIG. 5 illustrates schematically a user interface provided
on the casing of the data storage unit, for enabling a user to
select a disaster recover mode and activate a disaster recovery
method;
[0022] FIG. 6 illustrates schematically a user interface provided
on a casing of the data storage unit, for enabling a user to
activate an automatic disaster recovery method, selecting one of a
plurality of computer entities in a same bus;
[0023] FIG. 7 illustrates schematically data items stored for each
of a plurality of data storage media used by the data storage
unit;
[0024] FIG. 8 illustrates schematically a history list of data
storage media to which backup data has been written, and
identifying a location of each of the data storage media;
[0025] FIG. 9 illustrates schematically a method of operation of a
computer entity and the data storage unit for performing backup
operations;
[0026] FIG. 10 illustrates schematically in over view, processes of
a disaster recovery operation carried out by a data storage unit
and a computer entity according to a second specific method;
and
[0027] FIG. 11 illustrates schematically processes carried out by
the data storage unit in a disaster recovery operation according to
a third specific method.
DETAILED DESCRIPTION
[0028] There will now be described by way of example a specific
mode. In the following description numerous specific details are
set forth in order to provide a thorough understanding. It will be
apparent however, to one skilled in the art, that the present
invention may be practiced without limitation to these specific
details. In other instances, well known methods and structures have
not been described in detail so as not to unnecessarily obscure the
description.
[0029] In this specification, the term `tape drive unit` means a
device capable of performing read/write operations to a tape data
storage media, for example one contained in a tape data storage
media cartridge.
[0030] In this specification, the term `data storage unit` means a
device which is capable of storing data on a plurality of data
storage media, and which is capable of containing a plurality of
tape data storage media. A data storage unit may comprise a tape
drive unit, and the data storage unit may store a plurality of tape
data storage cartridges, which may be inserted into the tape drive
unit via a picker device or a robotic arm device, also comprised in
the data storage unit. The term data storage unit encompasses but
is not limited to devices of the autoloader type or of the library
type. A data storage unit may include an auto loader and/or library
data storage unit capable of performing unattended data storage
operations for a computer entity, or for a plurality of computer
entities attached to a same data bus.
[0031] The following SCSI terminology is commonly applied to
elements of a library or autoloader device:
[0032] A storage element refers to a storage slot or storage
location, where a tape data storage cartridge is stored within a
library device or autoloader device.
[0033] A data transfer element refers to a tape drive unit
component of a library device or autoloader device.
[0034] An import/export element refers to a slot or port through
which a tape data storage device can be inserted into an auto
loader or library data storage unit.
[0035] A data transport element refers to a robotic arm, and/or a
picker device for transferring a tape data storage cartridge from a
storage element to a data transfer element.
[0036] The above known terminology may be used to refer to
particular components of a data storage unit as described herein
below.
[0037] Referring to FIG. 3 herein, there is illustrated
schematically a host computer entity and a data storage unit
according to a specific implementation. The host computer entity
300 comprises a data storage disk 301, which contains an operating
system data, configuration data, application data, and user data;
and a back up application 302, also stored on the data storage disk
301, the back up application operable for regularly transferring
user data to the data storage unit, and for regularly transferring
operating system data and application data, along with
configuration settings to the data storage unit, in the form of a
CD image.
[0038] The data storage unit 304 comprises a tape drive unit 305
(also known as a data transfer element in the above mentioned SCSI
terminology) for writing to and reading from a plurality of tape
data storage cartridges; a controller 306; a host interface 307 for
interfacing with the host computer entity; a user interface 308
including a display device such as a liquid crystal display, and a
set of switches or buttons which can be activated by a human user;
a robotic arm mechanism 309 (also known as a data transport
element) along with an associated servo motor drive 310, the
robotic arm capable of grasping individual tape data storage
cartridges; a rack mechanism 311 having a plurality of locations
(also known as storage elements) for storage of a plurality of tape
data storage cartridges 312; and an internal bus 313 connecting the
tape drive unit, controller, host interface, user interface, and
servo motors. A data communications bus 314 connects the host
computer to the data storage unit.
[0039] The communications bus 314 may comprise an SCSI link, or a
fibre channel (FC) link as is known in the art. The data storage
unit retains a record of individual tape data storage media
cartridges which it contains, and a relative order in which those
data storage media cartridges were last written to. Where data is
stored to the tape data storage media, the data storage unit
records whether the write operation was successful or not for each
particular tape data storage media. Therefore, the data storage
unit is able to identify a last successfully written to tape data
storage media cartridge which it contains, and is able to present
that last successfully written to tape data storage media cartridge
to a computer entity, if requested to do so.
[0040] Successful writing of data to tape may be monitored by the
data storage unit in a variety of ways. The tape drive unit within
the data storage unit could be monitored to see if data has been
written to a tape data storage media. At the end of the write
process, which may be determined by for example a rewind operation,
or inactivity of the tape drive for a predetermined amount of time,
the assumption is made that a valid backup data storage operation
is being carried out, and therefore the tape data storage media is
correctly and successfully written to. The data storage unit stores
data identifying individual data storage media which had been
successfully written to, in chronological order, and in a time
order relative to each other, so that the data storage unit can
identify a last successfully written to tape data storage media, a
last but one successfully written to data storage media, and so on.
The data storage unit may do this by storing a data and/or time
data describing a data, and optionally, a time at which each data
storage unit was last successfully written to.
[0041] Referring to FIG. 4 herein, there is illustrated
schematically logical components of the controller device of the
data storage unit. The logical components comprise a database 400
for storing a list of data storage media, including information
describing the location of each data storage media, a date and time
on which each data storage media was last written to, and
optionally, a data field for identifying a computer entity of a
plurality of computer entities to which said last written data
relates to; a search algorithm 401 for searching for a said data
storage medium which has been written to latest, and for searching
for a most recently written to data storage medium containing data
relating to a particular computer entity; a recovery algorithm 402
for placing the data storage unit into a recovery mode in which a
most recently written to data storage medium is automatically
selected and placed in the tape drive unit ready for transfer of
data from the data storage unit to a computer entity; a display
driver 403 for generating a display from which a user may activate
a disaster recovery mode, and for generating a display list of said
data storage media; and a component 404 for determining whether a
tape data storage medium has been successfully written to or not.
The component 404, may implement an algorithm for determining
whether the tape media has been successfully written to or not.
[0042] The logical components of the controller device shown in
FIG. 4 may be implemented as a programmable logic array (PLA), or
may be implemented as a data processor and an associated non
volatile memory device, on which are stored program code
instructions for causing the processor to carry out the logical
functions.
[0043] Data written to tape data storage medium is tested at the
time of writing to see if the data is successfully written. At a
time of disaster recovery, the data from the tape data storage
cartridge is read back from the tape, the data is assumed to be
good data, since it was originally tested to have been successfully
written by the component 404.
[0044] Referring to FIG. 5 herein, there is illustrated
schematically one example of an interface display of a data storage
unit according to a specific implementation.
[0045] The display comprises a 2-dimensional liquid crystal visual
display 500; and a plurality of transport buttons, respectively for
moving a cursor forward 501, backwards 502, upwards 503 and
downwards 504; a cancel button 505, and an `OK` button 506 for
selecting a menu item.
[0046] In one implementation, a disaster recovery mode can be
selected by moving the transport buttons to select a disaster
recovery mode as a menu item displayed on the visual display
500.
[0047] In another implementation, to enter a disaster recovery
mode, a user presses a pre-set button, for example the `OK` select
button 506 for an extended period, for example 5 to 10 seconds.
This activates the controller 306 to enter a disaster recovery
mode.
[0048] Normally, a computer entity stores data directly over an
interface such as an SCSI interface, to an autoloader/library data
storage unit, and in a disaster recovery mode, boots directly from
that data storage unit. However, in one specific implementation, a
plurality of computer entities may be provided on a same bus, using
a same autoloader/library data storage unit. In this case, the data
storage unit may be partitioned to store data from a first computer
entity into a first partition, and to store data from a second
computer entity to a second partition. In these circumstances, the
data storage unit makes a note of which host computer is writing to
it, for each particular tape data storage cartridge.
[0049] Referring to FIG. 6 herein, in the disaster recovery mode, a
disaster recovery mode display is presented as shown in FIG. 6. In
the disaster recovery mode display, a list of computer entities
sharing a common bus for which the data storage unit has stored
back up data is displayed. In the general case, a data storage unit
may store back up data for a plurality of computers. For a small
installation, having only one computer entity, the data storage
unit may store back up data for only one computer, in which case no
selection of a computer entity needs to be made.
[0050] In the case where there are a plurality of computers, a user
can move a cursor on the display, using the transport buttons, and
select the computer which has encountered a catastrophic failure.
The data storage unit stores a list of tape data storage cartridges
for each computer entity on the bus, and stores data describing the
relative order in which those tape data storage cartridges were
last written to for that particular computer entity. The list of
tape data storage cartridges may be held for example, in reverse
chronological order. The data storage unit may also optionally
store an absolute date and/or time data for each tape data storage
cartridge, describing when that data storage cartridge was last
successfully written to.
[0051] Referring to FIG. 7 herein, there is illustrated
schematically data types stored for each tape data storage
cartridge within the data storage unit. Typically, for each
cartridge, data fields are created for data including: data
describing a computer entity for which recovery data is written to
a data storage medium; the date of a last occurrence of a write
operation to the tape data storage cartridge; a time of a last
write operation to the tape data storage cartridge; and a location
of the tape data storage cartridge within a rack or carrousel
system within the data storage unit, and/or data identifying
whether the tape cartridge is stored within the tape drive unit
itself.
[0052] Referring to FIG. 8 herein, there is illustrated
schematically a historical log stored in the non-volatile memory
device of the controller of the data storage unit, which lists
individual tape cartridges, by tape location, along with a relative
chronological information describing for each cartridge a time and
date at which that tape cartridge was last written to, as well as
(optionally) the computer entity which was used to write to that
tape data storage cartridge; and data describing whether a tape
cartridge is successfully written to or not.
[0053] Operation of the data storage unit in a disaster recovery
mode will now be described.
[0054] If a particular computer entity fails, first of all the
computer entity must be repaired, by installing a replacement hard
disk drive. This can include opening the casing of a computer
entity, once the computer is powered down, and swapping a
replacement hard disk for a damaged hard disk. The computer entity
is powered up, having been repaired. At this stage, the computer
entity cannot boot up, since the newly installed hard disk drive
unit does not contain an operating system, or any applications.
However, the computer entity can receive operating system data and
application data in a CD image format on power up.
[0055] The controller device of the data storage unit comprises a
non-volatile memory device which stores data recording each
computer entity for which the data storage unit stores backup data
location data describing; a rack location or carrousel location of
one or more cartridges for which backup data is stored for a
particular computer entity; and for each data storage cartridge, a
time and date data describing a time and date at which data was
last stored to said data storage cartridge.
[0056] Where the data storage unit adopts a disaster recovery mode,
there are various modes by which the data storage unit may
respond.
[0057] Firstly, the data storage unit may present a user interface
display presenting a list of backup tape data storage media in a
chronological order in which those tape date storage media were
last written to, listing the most recently written to tape date
storage media first. A user may manually select that tape data
storage media using the user interface and the controller may
control the robotic arm to select that particular cartridge from
its slot location (storage element), and place it in the tape drive
unit (data transfer element).
[0058] Secondly, an algorithm within the controller selects the
last successfully written to tape data storage cartridge for a
specified computer entity, and controls the autoloader robotics to
select that tape data storage cartridge from its rack location, and
place it in the tape drive unit, and instructs the tape drive unit
to adopt a CD emulation mode, in which a CD image can be read from
a predetermined location on the tape data storage cartridge.
[0059] Since tapes can only be inserted or removed from the data
storage unit, using the user interface, and through a port
(import/export element) in the casing of the storage unit, the
controller also keeps a record of any tapes which have been removed
from the data storage unit altogether for example by storing data
describing when the tape cartridge was removed from the data
storage unit.
[0060] Referring to FIG. 9 herein, there is illustrated
schematically processes carried out for performing a scheduled
backup operation 900 to a tape data storage medium. In process 901,
a backup application resident on the host computer selects files to
be backed-up. Alternatively, a user may select files to be
backed-up, using the backup application resident on the host
computer entity. In process 902, the backup application running on
the host computer selects which tape data storage cartridge to
load, in order to store backup data to. The backup application can
be set for different backup strategies. For example, in one backup
strategy, a different cartridge may be used for every day of the
week. In another backup strategy, full backups may be placed on one
tape, whilst incremental backups may be placed on another tape
cartridge. In process 903, the backup application running on the
host computer instructs the robotics controller in the data storage
unit to place the correct cartridge in the tape drive unit,
depending upon the backup strategy being followed. In process 904,
the controller of the data storage unit records information
describing the location slot of the cartridge which is being
backed-up, in the non-volatile memory of the controller. The time
and date are also recorded. In process 905, the backup application
running on the host computer writes backup data to the tape
cartridge. Additionally, the backup application writes a CD image
at a preset location on the tape data storage cartridge, which can
be used to reboot the computer entity. In process 906, once the
backup application has completed writing to tape, it may return the
cartridge to the original slot location, in the rack, or it may
keep the cartridge in the tape drive. The controller keeps a record
of the rack location of the tape cartridge which is currently held
in the tape drive units, so that if a disaster recovery operation
which would utilize that tape cartridge occurs, the data storage
unit is able to locate that particular cartridge as already being
in the tape drive unit. The data storage unit runs a validity
component to determine whether the tape is successfully written to,
and stores data describing the fact that the tape is successfully
written to, in a data entry for that tape data storage
cartridge.
[0061] Referring to FIG. 10 herein, there is illustrated
schematically overall processes carried out by a data storage unit,
in conjunction with a computer entity, for booting the computer
entity.
[0062] In process 1000, a user selects entry of a disaster recovery
mode at the data storage unit, by selecting a menu item on a visual
display of the data storage unit or activating a prolonged
depression of a transport button as described with referenced to
FIG. 6 herein before. This causes the data storage unit to enter a
disaster recovery mode. Once in the disaster recovery mode,
optionally the data storage unit displays a menu enabling a
computer entity to be selected from a list of computer entities.
The controller of the data storage unit reads a stored list of
computer entities from the memory of the controller unit, and
generates a visual display from which a user can select a computer
entity to be recovered. In process 1002, the controller of the data
storage unit identifies the last tape data storage cartridge which
has been written to by the selected computer entity. The data
records of each tape data storage cartridge stored locally in the
controller's memory are examined, to identify to last written to
tape cartridge. The controller commands the robotic arm to select
the last written to cartridge from the appropriate rack location
within the data storage unit, and to place the tape cartridge in
the tape drive unit. In process 1003, the controller commands the
tape drive unit to enter a CD emulation mode, in which the tape
drive unit emulates a CD device. The data storage unit displays on
the user interface a display instructions which instructs the user
to power cycle the computer entity, and to ensure that other
removable media drives of the computer entity are empty. The user
power-cycles the computer entity, after having first installed a
new hard disk drive. Upon power-cycling, the computer entity
searches its peripheral devices, of which the data storage unit is
one, the server scans the SCSI bus for devices which it can boot
from. The computer entity finds the data storage unit, which
emulates a CD and a BIOS of the computer initiates a transfer of
data from the tape drive unit to the computer, so that the computer
reads the bootable image from the tape cartridge, which is sent to
the computer entity as a CD image. The data storage unit responds
to the scan in process 1004, the tape drive unit making available
the bootable image in CD format. The computer entity reads the
bootable image from the tape cartridge in process 1005, and stores
it on its own internal hard disk drive unit. The bootable image on
the computer entity sets up an operating system, and a basic
configuration data from which the backup application and backup
data can be loaded from the tape data storage cartridge to re-store
the applications, configurations data and user data to the computer
entity. In process 1006 the backup application, which is loaded
onto the disk drive of the computer entity, signals to the data
storage unit to return the data storage unit into a tape drive
mode, or normal mode, in which the data storage unit can be
operated as a normal data storage device. In process 1007, the
backup application loaded onto the computer entity downloads
applications data, configuration data and user data in order to
restore the computer entity to a previous state which it held, at
the time of the most recent backup operation. Any changes to user
data or configuration data of the computer entity between a time of
the most recent backup operation and the disaster, may be lost,
however the computer entity may be restored to its most recent
backed up state.
[0063] Referring to FIG. 11 herein, there is illustrated
schematically processes carried out by the data storage unit for a
full disaster recovery operation of a failed computer entity.
[0064] The computer entity is repaired and a new hard disk drive
installed, in process 1100 a user puts the data storage unit into a
disaster recovery mode using the user interface as previously
described herein above. In process 1001, optionally, the user
selects a computer entity which has failed from a menu displayed on
the visual display device of the data storage unit. If the data
storage unit is permanently assigned to only one computer entity,
this step may be unnecessary. In process 1102, the controller of
the data storage unit automatically checks with its history log of
cartridge usage to determine which was the last written to tape
data storage cartridge for the specified computer entity. In
process 1103, the controller selects the last written to data
storage cartridge from its storage location within the rack and
loads it into the tape drive. If the tape data storage cartridge is
already in the tape drive, the controller can determine this from
an additional data which is stored in the non-volatile memory,
specifying the physical rack location of the tape cartridge which
is currently stored in the tape drive.
[0065] In process 1104 the controller puts the tape drive into a CD
emulation mode. In this mode, the tape drive unit appears over a
SCSI bus or other bus to behave as if it was a CD drive. In process
1105, the controller signals to the user to power up the computer
entity. This signal can be in the form of an audio signal or a
visual display on the visual display device. In an alternative
implementation, the controller may automatically send a signal to
the computer entity over the power management interface linking the
data storage unit and the computer entity, in order to power up the
computer entity. In process 1106, the computer entity is powered
up, either manually or from the user, or via the automatic signal
received over the power management interface and powercycles.
During the power cycling, the computer entity detects a CD in the
CD drive on the SCSI bus. This is the data storage unit emulating a
CD drive. In process 1107, the computer entity reads the CD image
from the tape cartridge. Typically, the CD image is stored at a
predetermined place on the tape data storage cartridge, for example
at the beginning of the tape. The CD image which contains an
operating system and backup application, is transferred over the
SCSI bus to the computer entity. In process 1108, the operating
system and backup application are loaded onto the hard disk drive
of the computer entity. Once on the hard disk drive, the operating
system a backup application can be rebooted on the computer entity.
In process 1109, the computer entity or the controller instructs
the tape drive unit to change from the CD emulation mode, into tape
drive operation, so that the operating system and the computer
entity can be used to load applications, configuration data and
user data over the SCSI bus onto the hard drive of the computer
entity, thereby restoring the computer entity into a known
configuration corresponding to the last time that a backup
operation had successfully been completed.
[0066] Specific implementations described herein may overcome a
limitation with prior art disaster recovery systems, that a human
user typically has no information as to which back up tape data
storage cartridge is the most recently written to media.
[0067] Specific implementations may have an advantage of
simplifying a disaster recovery operation for restoring a computer
entity back to a known state, whilst providing a simplified and
easy to use interface to a user.
[0068] Specific implementations described herein may provide for
automatic selection of a data storage cartridge from a plurality of
data storage cartridges, in which a most recent data set can be
recovered automatically, without a human user needing to remember
or make a record of which data storage cartridge contains the
latest or most recent data set.
[0069] Specific implementations may provide a robust data back up
system, in which a most recently written to data storage medium is
selected automatically from a plurality of stored data storage
media, in a disaster recovery situation.
[0070] According to various specific implementations herein, an
autoloader or library data storage unit, capable of automatically
loading any one of a plurality of data storage cartridges keeps a
record of the latest data storage cartridge to which data has been
written to. The data storage unit maintains a record in a
non-volatile memory, so that in the event of a catastrophic
computer entity failure, the last data storage media written for a
computer entity can be recovered using the information stored in
the data storage unit.
[0071] The data storage unit has a front panel user interface
and/or a remote management card which enables a user to activate
selection of the appropriate data storage cartridge in a simple
easy to understand and easy to use operation. Upon selection of a
disaster recovery mode by a user using a front panel of the data
storage unit, the data storage unit is placed in a CD emulation
mode, so that the data storage unit emulates a CD ROM. Since the
computer entity on power up is expecting a CD ROM to be loaded, the
data storage unit, emulating the CD ROM, can load a last
configuration data used by the computer entity, including an
operating system and a basic reduced version of a back up
application into the computer entity. Since selection of the
correct tape data storage cartridge is automatic, the computer
entity can be recovered to an operating system, and recovered back
up application and using the recovered backup application, the
computer can be restored using data on the tape to a state at which
it was in during the last back up operation, automatically with
minimal intervention from a user.
* * * * *