U.S. patent application number 14/451505 was filed with the patent office on 2016-02-04 for controlling wear among flash memory devices based on remaining warranty.
The applicant listed for this patent is International Business Machines Corporation. Invention is credited to William M. Megarity, Emil P. Parker, Luke D. Remis, Christopher L. Wood.
Application Number | 20160034387 14/451505 |
Document ID | / |
Family ID | 55180169 |
Filed Date | 2016-02-04 |
United States Patent
Application |
20160034387 |
Kind Code |
A1 |
Megarity; William M. ; et
al. |
February 4, 2016 |
CONTROLLING WEAR AMONG FLASH MEMORY DEVICES BASED ON REMAINING
WARRANTY
Abstract
A method includes identifying a product warranty for each of a
plurality of flash memory devices within a system, wherein the
product warranty includes a maximum number of writes and a maximum
age, and tracking the number of writes made to each flash memory
device and the age of each flash memory device. The method further
includes determining, for each flash memory device, a number of pro
rata writes remaining in the product warranty, which is determined
as a number of writes remaining until the flash memory device
reaches the maximum number of writes identified in the product
warranty divided by an amount of time remaining until the flash
memory reaches the maximum age identified in the product warranty.
The method then causes data to be written to the flash memory
device having the greatest number of pro rata writes remaining in
the product warranty.
Inventors: |
Megarity; William M.;
(Raleigh, NC) ; Parker; Emil P.; (Youngsville,
NC) ; Remis; Luke D.; (Raleigh, NC) ; Wood;
Christopher L.; (Greenville, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Family ID: |
55180169 |
Appl. No.: |
14/451505 |
Filed: |
August 5, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14450437 |
Aug 4, 2014 |
|
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14451505 |
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Current U.S.
Class: |
711/103 |
Current CPC
Class: |
G06F 2212/7204 20130101;
G06F 12/0246 20130101; G06F 2212/1036 20130101; G06F 12/0871
20130101; G06F 2212/7211 20130101; G06F 2212/284 20130101; G06F
2212/222 20130101; G06F 2212/2022 20130101 |
International
Class: |
G06F 12/02 20060101
G06F012/02 |
Claims
1. A method, comprising: identifying a product warranty for each of
a plurality of flash memory devices within a system, wherein the
product warranty includes a maximum number of writes and a maximum
age; tracking the number of writes made to each flash memory device
and the age of each flash memory device; determining, for each
flash memory device, a number of pro rata writes remaining in the
product warranty, wherein the number of pro rata writes remaining
in the product warranty is determined as a number of writes
remaining until the flash memory device reaches the maximum number
of writes identified in the product warranty divided by an amount
of time remaining until the flash memory reaches the maximum age
identified in the product warranty; and causing data to be written
to the flash memory device having the greatest number of pro rata
writes remaining in the product warranty.
2. The method of claim 1, further comprising: identifying one of
the flash memory devices having the least amount of time remaining
until the flash memory reaches the product age identified in the
product warranty; and increasing a rate of writing data to the
identified flash memory device so that the number of writes made to
the identified flash memory device reaches the maximum number of
writes identified in the product warranty at approximately the same
time as the age of the identified flash memory device reaches the
maximum age identified in the product warranty.
3. The method of claim 1, wherein the flash memory is a component
of a device selected from a solid state drive, a serial bus
attached data storage device, and a flash memory module card.
4. The method of claim 1, wherein the plurality of flash memory
devices form a single logical memory device.
5. The method of claim 1, wherein the plurality of flash memory
devices are cache memory for a plurality of hard disk drives.
6. The method of claim 1, wherein the step of determining, for each
flash memory device, a number of pro rata writes remaining in the
product warranty is performed by an operating system of a computer
in communication with the plurality of flash memory devices.
7. The method of claim 1, wherein the step of determining, for each
flash memory device, a number of pro rata writes remaining in the
product warranty is performed by an controller coupled to the
plurality of flash memory devices.
8. The method of claim 1, further comprising: wear leveling data
stored on each flash memory device.
9. The method of claim 1, wherein wear leveling data stored on each
flash memory device is performed by a controller within each flash
memory device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/450,437 filed on Aug. 4, 2014, which
application is incorporated by reference herein.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to methods of distributing the
writing of data among a plurality of flash memory devices.
[0004] 2. Background of the Related Art
[0005] Flash memory is a form of non-volatile computer readable
storage medium that is used for high-speed and high-density data
storage solutions. However, flash memory cells within a flash
memory device experience wear over a large number of write cycles.
Many manufactures of flash memory will rate their flash memory
devices at a given number of write cycles or similar usage
parameter.
[0006] Flash memory devices typically include a local controller
for handling read and write operations to the flash memory. The
local controller may use a wear leveling algorithm to distribute
writes across all of the memory cell blocks within the flash memory
device. Such wear leveling assures that the memory cell blocks wear
at about the same rate, rather than over-utilizing some memory cell
blocks and under-utilizing other memory cell blocks.
BRIEF SUMMARY
[0007] One embodiment of the present invention provides a method,
comprising identifying a product warranty for each of a plurality
of flash memory devices within a system, wherein the product
warranty includes a maximum number of writes and a maximum age, and
tracking the number of writes made to each flash memory device and
the age of each flash memory device. The method further comprises
determining, for each flash memory device, a number of pro rata
writes remaining in the product warranty, wherein the number of pro
rata writes remaining in the product warranty is determined as a
number of writes remaining until the flash memory device reaches
the maximum number of writes identified in the product warranty
divided by an amount of time remaining until the flash memory
reaches the maximum age identified in the product warranty. The
method then causes data to be written to the flash memory device
having the greatest number of pro rata writes remaining in the
product warranty.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] FIG. 1 is a diagram of a system including a controller that
manages the distribution of writes to a plurality of flash memory
devices.
[0009] FIG. 2 is a hypothetical table that might be maintained by a
controller that determines the pro rata writes remaining under the
warranty for each flash memory device within a system.
[0010] FIG. 3 is a hypothetical table that might be maintained by a
controller that determines the flash memory device having the least
number of remaining days under warranty.
[0011] FIG. 4 is a flowchart of a method in accordance with one
embodiment of the present invention.
DETAILED DESCRIPTION
[0012] One embodiment of the present invention provides a method,
comprising identifying a product warranty for each of a plurality
of flash memory devices within a system, wherein the product
warranty includes a maximum number of writes and a maximum age, and
tracking the number of writes made to each flash memory device and
the age of each flash memory device. The method further comprises
determining, for each flash memory device, a number of pro rata
writes remaining in the product warranty, wherein the number of pro
rata writes remaining in the product warranty is determined as a
number of writes remaining until the flash memory device reaches
the maximum number of writes identified in the product warranty
divided by an amount of time remaining until the flash memory
reaches the product age identified in the product warranty. The
method then causes data to be written to the flash memory device
having the greatest number of pro rata writes remaining in the
product warranty.
[0013] The step of determining a number of pro rata writes
remaining in the product warranty for each flash memory device may,
for example, be performed by an operating system of a computer in
communication with the plurality of flash memory devices, by a
controller coupled to the plurality of flash memory devices, or
some combination of devices.
[0014] The product warranty may be obtained as a data file stored
on the individual flash memory device or downloaded from an online
source of product warranty information. Alternatively, a user may
manually enter the product warranty into a graphical user interface
to the controller or operating system that performs the method.
[0015] Tracking of the number of writes made to each flash memory
device and the age of each flash memory device may be performed by
the controller or operating system that executes the method.
Alternatively, the tracking may be performed by the individual
flash memory device, where the controller or operating system
subsequently obtains an update of the tracking data from each of
the flash memory devices.
[0016] In one optional aspect of the invention, the method may
further comprise identifying one of the flash memory devices having
the least amount of time remaining until the flash memory reaches
the product age identified in the product warranty, and increasing
a rate of writing data to the identified flash memory device so
that the number of writes made to the identified flash memory
device reaches the maximum number of writes identified in the
product warranty at approximately the same time as the age of the
identified flash memory device reaches the maximum age identified
in the product warranty. Accordingly, additional writes are focused
toward those flash memory devices that are about to go off warranty
due to age so that the warrantied number of write may be executed
before, or simultaneous with, the flash memory device reaching the
maximum age identified in the warranty.
[0017] The flash memory devices may take various forms or
configurations, and a system may include one or more of these forms
or configurations of devices. Non-limiting examples of the flash
memory devices include solid state drives, serial bus attached data
storage devices, flash memory module cards, universal serial bus
(USB) flash drives, and cache memory for a hard disk drive.
Optionally, the plurality of flash memory devices may form a single
logical memory device.
[0018] Still further, the method may further comprise wear leveling
data stored on each flash memory device. This wear leveling is
performed by a local controller that is part of the individual
flash memory device and works to provide an approximately equal
number of writes across the entire flash memory. Accordingly, the
wear leveling addresses the longevity of the individual flash
memory devices, whereas the efficient use of the product warranty
for each flash memory device is addressed by causing data to be
written to the flash memory device having the greatest number of
pro rata writes remaining in the product warranty.
[0019] One embodiment of the present invention provides a computer
readable storage medium having program instructions embodied
therewith, the program instructions executable by a processor to
cause the processor to perform a method. The method comprises
identifying a product warranty for each of a plurality of flash
memory devices within a system, wherein the product warranty
includes a maximum number of writes and a maximum age, and tracking
the number of writes made to each flash memory device and the age
of each flash memory device. The method further comprises
determining, for each flash memory device, a number of pro rata
writes remaining in the product warranty, wherein the number of pro
rata writes remaining in the product warranty is determined as a
number of writes remaining until the flash memory device reaches
the maximum number of writes identified in the product warranty
divided by an amount of time remaining until the flash memory
reaches the product age identified in the product warranty. The
method then causes data to be written to the flash memory device
having the greatest number of pro rata writes remaining in the
product warranty.
[0020] The foregoing computer readable storage medium may embody
further program instructions for implementing or initiating any one
or more aspects of the methods described herein. Accordingly, a
separate description of the methods will not be duplicated in the
context of a computer readable storage medium.
[0021] FIG. 1 is a diagram of a system 10 including a controller 20
that manages the distribution of data writes to a plurality of
flash memory devices 40. The controller 20 obtains or determines
the product warranties 22 for each of the flash memory devices 40,
where each product warranty includes the maximum number of writes
24 and the maximum age 26 covered by the product warranty. The
controller 20 also obtains or determines product use data 28 for
each of the flash memory devices 40, where the product use data
identifies the actual number of writes 30 performed on the device
and the actual age 32 of the device. Device control logic 34
executed by the controller 20 may then use the product warranties
22 and the product use data 28 in order to dynamically prioritize
the writing of data to the flash memory devices 40. For example,
flash memory devices 40 that are nearing the end of an age-based
warranty, but having high number of writes remaining under
warranty, may be given a higher priority while other flash memory
devices 40 having a longer period before reaching the end of the
age-based warranty may be given a lower priority. In a further
option, the write rate for each device would be dynamically
adjusted to ensure both warranties exhaust simultaneously.
[0022] Each of plurality of flash memory devices 40 may be
different types and sizes, but are shown as each including a local
controller 42 and flash memory 44 forming a caching layer for a
hard disk drive 46. With or without the hard disk drive 46, the
local controller 42 may perform wear level on the flash memory
44.
[0023] As shown, the flash memory 44 is used as a caching layer in
order to provide faster write access than a spinning platter of the
hard disk drive 46, while also be non-volatile so that data is not
lost whenever there is a loss of power. Furthermore, the system 10
may form a single logical unit that receives and executed writes as
a single data storage unit.
[0024] FIG. 2 is a hypothetical table 50 that might be maintained
by the controller 20 for determining the pro rata writes remaining
under the product warranty for each flash memory device 40 within
the system 10. The table 50 includes data for each of the flash
memory devices 40, illustrated here as one row of data for each of
the Flash Memory Devices 1-4. For each of the flash memory devices,
the table 50 identifies the maximum writes 24 and the maximum age
(days) 26 identified in the product warranties 22, as well as the
actual number of writes 30 and age 32 identified in the product use
data 28. Accordingly, the device selection logic 34 may determine
the pro rata writes 52 (number of writes per day) remaining under
the warranty. The pro rata writes may be determined using the
equation: Pro Rata Writes=(Max. Writes-Writes)/(Max. Age-Age). As
shown, the controller has identified Flash Memory Device 3 as have
the highest rank 54 or priority for receiving writes, since Flash
Memory Device 3 needs 3,949 writes/day in order for the writes
under warranty to become exhausted by the time the device reaches
its maximum age under warranty. As possible, the controller should
send more writes to Flash Memory Device 3 than the other devices.
Preferably, the controller may send writes to the Flash Memory
Devices 1-4 in proportion to their pro rate writes remaining.
[0025] FIG. 3 is a hypothetical table 60 that might be maintained
by the controller for determining the flash memory device having
the least number of remaining days under warranty. The first five
columns of table 60 are the same as the first five columns of table
50 in FIG. 2. However, the number of days remaining under warranty
62 has been determined by subtracting the age 32 of the device from
the maximum age 26 identified in the product warranty 22 for that
device. Then, a rank 64 identifies that Flash Memory Device 4 has
the least number of days remaining in the warranty. The method may
optionally adjust the number of writes to Flash Memory Device 4
over the final 40 days until its warranty expires in order to use
all or most of the remaining writes by the time the device reaches
the maximum age identified in the warranty. Accordingly, despite
Flash Memory Device 3 have the highest pro rata writes remaining 52
(FIG. 2), the controller should prioritize sending an average of
1,289 writes per day to Flash Memory Device 4 in order to maximize
the efficient use of the warranty.
[0026] FIG. 4 is a flowchart of a method 70 in accordance with one
embodiment of the present invention. In step 72, a product warranty
is identified for each of a plurality of flash memory devices
within a system, wherein the product warranty includes a maximum
number of writes and a maximum age. Step 74 tracks the number of
writes made to each flash memory device and the age of each flash
memory device. Step 76 then determines, for each flash memory
device, a number of pro rata writes remaining in the product
warranty, wherein the number of pro rata writes remaining in the
product warranty is determined as a number of writes remaining
until the flash memory device reaches the maximum number of writes
identified in the product warranty divided by an amount of time
remaining until the flash memory reaches the product age identified
in the product warranty. In step 78, the method causes data to be
written to the flash memory device having the greatest number of
pro rata writes remaining in the product warranty.
[0027] The present invention may be a system, a method, and/or a
computer program product. The computer program product may include
a computer readable storage medium (or media) having computer
readable program instructions thereon for causing a processor to
carry out aspects of the present invention.
[0028] The computer readable storage medium can be a tangible
device that can retain and store instructions for use by an
instruction execution device. The computer readable storage medium
may be, for example, but is not limited to, an electronic storage
device, a magnetic storage device, an optical storage device, an
electromagnetic storage device, a semiconductor storage device, or
any suitable combination of the foregoing. A non-exhaustive list of
more specific examples of the computer readable storage medium
includes the following: a portable computer diskette, a hard disk,
a random access memory (RAM), a read-only memory (ROM), an erasable
programmable read-only memory (EPROM or Flash memory), a static
random access memory (SRAM), a portable compact disc read-only
memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a
floppy disk, a mechanically encoded device such as punch-cards or
raised structures in a groove having instructions recorded thereon,
and any suitable combination of the foregoing. A computer readable
storage medium, as used herein, is not to be construed as being
transitory signals per se, such as radio waves or other freely
propagating electromagnetic waves, electromagnetic waves
propagating through a waveguide or other transmission media (e.g.,
light pulses passing through a fiber-optic cable), or electrical
signals transmitted through a wire.
[0029] Computer readable program instructions described herein can
be downloaded to respective computing/processing devices from a
computer readable storage medium or to an external computer or
external storage device via a network, for example, the Internet, a
local area network, a wide area network and/or a wireless network.
The network may comprise copper transmission cables, optical
transmission fibers, wireless transmission, routers, firewalls,
switches, gateway computers and/or edge servers. A network adapter
card or network interface in each computing/processing device
receives computer readable program instructions from the network
and forwards the computer readable program instructions for storage
in a computer readable storage medium within the respective
computing/processing device.
[0030] Computer readable program instructions for carrying out
operations of the present invention may be assembler instructions,
instruction-set-architecture (ISA) instructions, machine
instructions, machine dependent instructions, microcode, firmware
instructions, state-setting data, or either source code or object
code written in any combination of one or more programming
languages, including an object oriented programming language such
as Smalltalk, C++ or the like, and conventional procedural
programming languages, such as the "C" programming language or
similar programming languages. The computer readable program
instructions may execute entirely on the user's computer, partly on
the user's computer, as a stand-alone software package, partly on
the user's computer and partly on a remote computer or entirely on
the remote computer or server. In the latter scenario, the remote
computer may be connected to the user's computer through any type
of network, including a local area network (LAN) or a wide area
network (WAN), or the connection may be made to an external
computer (for example, through the Internet using an Internet
Service Provider). In some embodiments, electronic circuitry
including, for example, programmable logic circuitry,
field-programmable gate arrays (FPGA), or programmable logic arrays
(PLA) may execute the computer readable program instructions by
utilizing state information of the computer readable program
instructions to personalize the electronic circuitry, in order to
perform aspects of the present invention.
[0031] Aspects of the present invention are described herein with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems), and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer readable
program instructions.
[0032] These computer readable program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or blocks.
These computer readable program instructions may also be stored in
a computer readable storage medium that can direct a computer, a
programmable data processing apparatus, and/or other devices to
function in a particular manner, such that the computer readable
storage medium having instructions stored therein comprises an
article of manufacture including instructions which implement
aspects of the function/act specified in the flowchart and/or block
diagram block or blocks.
[0033] The computer readable program instructions may also be
loaded onto a computer, other programmable data processing
apparatus, or other device to cause a series of operational steps
to be performed on the computer, other programmable apparatus or
other device to produce a computer implemented process, such that
the instructions which execute on the computer, other programmable
apparatus, or other device implement the functions/acts specified
in the flowchart and/or block diagram block or blocks.
[0034] The flowchart and block diagrams in the Figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of instructions, which comprises one
or more executable instructions for implementing the specified
logical function(s). In some alternative implementations, the
functions noted in the block may occur out of the order noted in
the figures. For example, two blocks shown in succession may, in
fact, be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved. It will also be noted that each block of
the block diagrams and/or flowchart illustration, and combinations
of blocks in the block diagrams and/or flowchart illustration, can
be implemented by special purpose hardware-based systems that
perform the specified functions or acts or carry out combinations
of special purpose hardware and computer instructions.
[0035] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, components and/or groups, but do not
preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components, and/or groups
thereof. The terms "preferably," "preferred," "prefer,"
"optionally," "may," and similar terms are used to indicate that an
item, condition or step being referred to is an optional (not
required) feature of the invention.
[0036] The corresponding structures, materials, acts, and
equivalents of all means or steps plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but it is not intended to be exhaustive or limited to
the invention in the form disclosed. Many modifications and
variations will be apparent to those of ordinary skill in the art
without departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated.
* * * * *