Process and apparatus to reduce declared capacity of a storage device by altering an encoding format

Patent metadata

Field	Value
Publication number	US-9524105-B2
Application number	US-201514621212-A
Country	US
Kind code	B2
Filing date	Feb 12, 2015
Priority date	Sep 2, 2014
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

Systems, methods and/or devices are used to reduce declared capacity of non-volatile memory of a storage device in a storage system. In one aspect, the method includes, detecting an amelioration trigger for reducing declared capacity of non-volatile memory of a storage device of the storage system, and in accordance with the detected amelioration trigger, performing an amelioration process to reduce declared capacity of the non-volatile memory of the storage device, the performing including: altering an encoding format of at least a portion of the non-volatile memory of the storage device, and reducing declared capacity of the non-volatile memory of the storage device. In some embodiments, the storage device includes one or more flash memory devices. In some embodiments, the detecting, the performing, or both are performed by the storage device, or by one or more subsystems of the storage system distinct from the storage device, or by the host.

First claim

What is claimed is:

1. A method of managing a storage system, the method comprising:
detecting an amelioration trigger for reducing declared capacity of non-volatile memory of a storage device of the storage system, wherein declared capacity is storage capacity available to a host;
in accordance with the detected amelioration trigger, performing an amelioration process to reduce declared capacity of the non-volatile memory of the storage device, the performing including:
altering an encoding format of at least a portion of the non-volatile memory of the storage device; and
reducing declared capacity of the non-volatile memory of the storage device;

prior to detecting the amelioration trigger, detecting a first wear condition of the non-volatile memory of the storage device, wherein a total storage capacity of the non-volatile memory of the storage device includes declared capacity and over-provisioning; and
in response to detecting the first wear condition, performing a remedial action that reduces over-provisioning of the non-volatile memory of the storage device without reducing declared capacity of the non-volatile memory of the storage device.

2. The method of claim 1 , wherein detecting the amelioration trigger comprises detecting a second wear condition distinct from the first wear condition.

3. The method of claim 1 , wherein the detecting the amelioration trigger, the performing the amelioration process, or both the detecting the amelioration trigger and the performing the amelioration process are performed by the storage device.

4. The method of claim 1 , wherein the detecting the amelioration trigger, the performing the amelioration process, or both the detecting the amelioration trigger and the performing the amelioration process are performed by one or more subsystems of the storage system distinct from the storage device.

5. The method of claim 1 , wherein the detecting the amelioration trigger, the performing the amelioration process, or both the detecting the amelioration trigger and the performing the amelioration process are performed by the host.

6. The method of claim 1 , wherein the host includes a client on behalf of which data is stored in the storage system.

7. The method of claim 1 , wherein the host includes a cluster controller of the storage system or a storage system controller of the storage system.

8. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format of at least a portion of the non-volatile memory of the storage device in accordance with one or more parameters for the amelioration process.

9. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format from a higher-density physical encoding format to a lower-density physical encoding format.

10. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering a number of states per memory cell from a higher number of states to a lower number of states.

11. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format from a Triple-Level Cell (TLC) format to a Multi-Level Cell (MLC) format.

12. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format from a Triple-Level Cell (TLC) format to a Single-Level Cell (SLC) format.

13. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format from a Multi-Level Cell (MLC) format to a Single-Level Cell (SLC) format.

14. The method of claim 1 , wherein performing the amelioration process to reduce declared capacity of the non-volatile memory of the storage device includes reducing utilization of the non-volatile memory of the storage device.

15. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format of a memory portion of a plurality of memory portions of the non-volatile memory of the storage device.

16. The method of claim 1 , wherein altering the encoding format of at least a portion of the non-volatile memory of the storage device includes altering the encoding format of all client data of the non-volatile memory of the storage device.

17. The method of claim 1 , wherein performing the amelioration process to reduce declared capacity of the non-volatile memory of the storage device further includes advertising a reduced declared capacity of the non-volatile memory of the storage device.

18. The method of claim 1 , further comprising:
after beginning performance of the amelioration process to reduce declared capacity of the non-volatile memory of the storage device, detecting an indication to abort the reduction in declared capacity of the non-volatile memory of the storage device;
in response to detecting the indication to abort the reduction in declared capacity of the non-volatile memory of the storage device, aborting performance of the amelioration process to reduce declared capacity of the non-volatile memory of the storage device.

19. The method of claim 1 , wherein the storage device comprises one or more flash memory devices.

20. A storage device, comprising:
non-volatile memory;
one or more processors; and
controller memory storing one or more programs, which when executed by the one or more processors cause the storage device to perform operations comprising:
detecting an amelioration trigger for reducing declared capacity of the non-volatile memory of the storage device, wherein declared capacity is storage capacity available to a host;
in accordance with the detected amelioration trigger, performing an amelioration process to reduce declared capacity of the non-volatile memory of the storage device, the performing including:
altering an encoding format of at least a portion of the non-volatile memory of the storage device; and
reducing declared capacity of the non-volatile memory of the storage device;

prior to detecting the amelioration trigger, detecting a first wear condition of the non-volatile memory of the storage device, wherein a total storage capacity of the non-volatile memory of the storage device includes declared capacity and over-provisioning; and
in response to detecting the first wear condition, performing a remedial action that reduces over-provisioning of the non-volatile memory of the storage device without reducing declared capacity of the non-volatile memory of the storage device.

21. The storage device of claim 20 , wherein performing the amelioration process to reduce declared capacity of the non-volatile memory of the storage device further includes advertising a reduced declared capacity of the non-volatile memory of the storage device.

22. The storage device of claim 20 , wherein the storage device comprises one or more flash memory devices.

23. A non-transitory computer readable storage medium, storing one or more programs configured for execution by one or more processors of a storage device, the one or more programs including instru

Assignees

• Sandisk Technologies Llc

Inventors

• Samuels Allen
• Kruger Warren Fritz
• Truong Linh Tien

Classifications

• G11C2211/5641

  Multilevel memory having cells with different number of storage levels · CPC title

• G11C16/08

  Address circuits; Decoders; Word-line control circuits · CPC title

• G11C16/349

  Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles · CPC title

• G06F12/0246 Primary

  in block erasable memory, e.g. flash memory · CPC title

• G06F2212/7205

  Cleaning, compaction, garbage collection, erase control · CPC title