APPARATUS, SYSTEM, AND METHOD FOR WEAR MANAGEMENT

• US 20130232289A1
• Filed: 03/15/2013
• Published: 09/05/2013
• Est. Priority Date: 11/10/2008
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Fusion-IO Incorporated (Western Digital Corporation)
• Inventors: Zhong, Hao, Wood, Robert, Sun, Hairong, Plasson, Ned D., Woong, Jea
• Granted Patent: US 9,063,874 B2
• Time in Patent Office: Days
• US Class Current: 711/102
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 11/141 for bus or memory accesses
• CPC Class Codes: G06F 11/3034 where the computing system component is a storage system, e.g. DASD based or network based digital input from or digital output to record carriers G06F3/06; digital recording or reproducing G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/3055 Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction by redundancy in operation G06F11/14; error detection or correction by redundancy in hardware G06F11/16
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2211/109 Sector level checksum or ECC, i.e. sector or stripe level checksum or ECC in addition to the RAID parity calculation
• CPC Class Codes: G11C 16/04 using variable threshold transistors, e.g. FAMOS
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data
• CPC Class Codes: G11C 16/3422 Circuits or methods to evaluate read or write disturbance in nonvolatile memory, without steps to mitigate the problem
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles
• CPC Class Codes: G11C 16/3495 Circuits or methods to detect or delay wearout of nonvolatile EPROM or EEPROM memory devices, e.g. by counting numbers of erase or reprogram cycles, by using multiple memory areas serially or cyclically
• CPC Class Codes: G11C 2029/0411 Online error correction
• CPC Class Codes: G11C 2029/1208 Error catch memory
• CPC Class Codes: G11C 29/42 using error correcting codes [ECC] or parity check
• CPC Class Codes: G11C 29/82 for EEPROMs
• CPC Class Codes: G11C 29/832 with disconnection of faulty elements
• CPC Class Codes: G11C 29/88 with partially good memories

Abstract

A storage module is configured to determine a health metric of a storage division of a solid-state storage medium. The health metric may comprise a combination of factors, including, but not limited to: wear level, performance (e.g., program time, erase time, and the like), error rate, and the like. A wear level module may configure storage operations to reduce the wear rate of storage divisions having poor health metrics and/or heath metrics that are degrading more quickly than other storage divisions. Reducing wear rate may include deferring grooming operations, delaying use for storage operations, temporarily retiring the storage division, or the like. Storage divisions may be brought back into service at normal use rates in response determining that other portions of the storage media have been worn to the point that they exhibit similar health and/or reliability characteristics.

Claims

1. A method, comprising:

determining an overall reliability metric of a solid-state storage medium based on reliability metrics of a plurality of different sections of the solid-state storage medium;

identifying a section of the solid-state storage medium having a reliability metric that differs from the overall reliability metric by more than a threshold; and

managing storage operations performed on the solid-state storage medium to adjust wear of the identified section in response to the storage operations.

2. The method of claim 1, wherein managing the storage operations comprises relocating valid data from the identified section and deferring a reclamation operation on the identified section.

3. The method of claim 1, wherein managing the storage operations comprises identifying a storage request pertaining to cold data, and storing the cold data on the identified section.

4. The method of claim 1, further comprising indicating that the identified section is out-of-service.

5. The method of claim 4, further comprising indicating that the identified section is in service and available for storing data in response to determining that a differential between the reliability metric of the identified section and a new overall reliability metric of the solid-state storage medium determined after performing a plurality of storage operations on the solid-state storage medium is within the threshold.

6. The method of claim 1, further comprising:

determining an updated overall reliability metric of the solid-state storage medium subsequent to identifying the section; and

managing storage operations performed on the solid-state storage medium to adjust wear of the identified section in response to determining that the reliability metric of the identified section is within the threshold of the updated overall reliability metric.

7. The method of claim 1, further comprising:

recording indications of reduced wear sections of the solid-state storage medium; and

accessing the indications to schedule storage operations on the solid-state storage medium.

8. The method of claim 7, further comprising recording the indications on a non-volatile storage medium.

9. The method of claim 1, wherein the reliability metric is based on one or more of a raw bit error rate of the section, a program time of the section, an erase time of the section, and a program count of the section.

10. An apparatus, comprising:

a reliability analysis module configured to determine an aggregate health metric corresponding to respective health metrics of storage divisions of a solid-state storage medium and to identify a set of one or more storage divisions having health metrics that deviate from the aggregate health metric by more than a threshold; and

a wear management module configured to adapt storage operations performed on the identified set of storage divisions to manage usage of the identified set of storage divisions.

11. The apparatus of claim 10, further comprising a reliability monitoring module configured to determine the respective health metrics of a plurality of storage divisions of a solid-state storage device, wherein the storage division health metrics are based on performance characteristics of the storage divisions.

12. The apparatus of claim 10, further comprising a groomer module configured to prepare storage divisions for use by relocating valid data from the storage divisions and initializing the storage divisions, wherein the groomer module is configured to relocate valid data from one of the identified set of storage divisions and to delay initializing the storage division.

13. The apparatus of claim 10, further comprising log storage module configured to queue storage divisions for data storage operations, wherein the log storage module is configured to remove one or more of the identified set of storage divisions from the queue.

14. The apparatus of claim 13, wherein the log storage module is configured to queue one or more of the identified storage divisions in a reduced usage queue, and to schedule a storage operation on a storage division in the reduced usage queue in response to receiving a storage request pertaining to low-usage data.

15. The apparatus of claim 13, wherein the log storage module is configured to queue the storage divisions in an ordered queue, and to reorder one or more of the identified set of storage divisions to an end of the ordered queue.

16. The apparatus of claim 10, wherein the reliability analysis module is configured to remove a storage division from the identified set of storage divisions in response to determining that a deviation between the health metric of the storage division and an updated aggregate health metric is less than the threshold.

17. A system, comprising:

means for identifying a first set of a plurality of solid-state storage sections having reliability characteristics that differ from reliability characteristics of a second set of the plurality of solid-state storage sections by more than a threshold;

means for receiving a plurality of requests to perform storage operations on the solid-state storage sections; and

means for modifying a sequential storage pattern for the requested storage operations to vary usage of the first set of solid-state storage sections as compared to usage of the second set of solid-state storage sections.

18. The system of claim 17, further comprising means for determining reliability characteristics of the storage sections comprising means for monitoring one or more of error rates of the storage sections, program times of the storage sections, and erase times of the storage sections.

19. The system of claim 18, further comprising:

means for determining updated reliability characteristics of the others of the solid-state storage sections; and

means for selecting a storage section for removal from the first set and inclusion in the second set in response to determining that reliability characteristics of the selected storage section are within a deviation threshold of the updated reliability characteristics of the solid-state storage divisions in the second set.

20. The system of claim 17, further comprising means for grooming solid-state storage sections for reuse comprising means for delaying reuse of storage sections in the first set.

21. The system of claim 17, further comprising means for queuing the storage operations on the solid-state storage sections configured to prevent storage operations from being queued to the solid-state storage sections in the first set.