SELF RECOVERY IN A SOLID STATE DRIVE

• US 20140258587A1
• Filed: 03/12/2013
• Published: 09/11/2014
• Est. Priority Date: 03/06/2013
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Baryudin, Leonid, Cohen, Earl T., Tang, Alex G.
• Granted Patent: US 9,122,587 B2
• Time in Patent Office: Days
• US Class Current: 711/102
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7209 Validity control, e.g. using flags, time stamps or sequence numbers

Abstract

An apparatus having a nonvolatile memory and a controller. The memory stores information in multiple pages. The information includes data units and headers. Each data unit is associated with a respective identifier in an address space of the apparatus and a respective location in the memory, has a respective header having the respective identifier, and is associated with a respective time stamp. Multiple headers include ones of the time stamps. The controller is configured to (i) read information stored in the pages, (ii) determine an order in which the data units were written based on the time stamps, (iii) locate based on the order (a) each last-written occurrence of the respective identifiers and (b) the respective locations of the data units associated with the last-written occurrences, and (iv) rebuild a map of the controller according to the respective locations of each last-written occurrence of each respective identifier.

Claims

1. An apparatus comprising:

a memory configured to store information in a plurality of pages, wherein (i) said memory is nonvolatile, (ii) said information comprises a plurality of data units and a plurality of headers, (iii) each of said data units is associated with a respective identifier in an address space of said apparatus and a respective location in said memory, (iv) each of said data units has a respective one of said headers comprising said respective identifier, (v) each of said data units is associated with a respective one of a plurality of time stamps and (vi) multiple ones of said headers comprise ones of said time stamps; and

a controller configured to (i) read information stored in said pages, (ii) determine an order in which said data units were written to said memory based on said time stamps, (iii) locate based on said order (a) each last-written occurrence of said respective identifiers and (b) said respective locations of said data units associated with said last-written occurrences, and (iv) rebuild a map of said controller according to said respective locations of each of said last-written occurrence of each of said respective identifiers.

2. The apparatus according to claim 1, wherein said memory and said controller are part of a solid-state drive.

3. The apparatus according to claim 1, wherein said rebuild comprises storing a respective length of each of said last-written occurrences of each of said respective identifiers in said map.

4. The apparatus according to claim 3, wherein said rebuild further comprises storing said respective lengths in said map.

5. The apparatus according to claim 3, wherein said respective length of a first of said last-written occurrences differs from said respective length of a second of said last-written occurrences.

6. The apparatus according to claim 1, wherein said determine, said locate, and said rebuild are performed in response to a corruption of said map.

7. The apparatus according to claim 1, wherein said controller is further configured to parse at least some of said headers stored in a subset of said pages to determine data suitable to decrypt encrypted ones of said pages.

8. The apparatus according to claim 1, wherein said controller is further configured to initiate a self recovery in response to a signal received from a computer, wherein said map is rebuilt in said computer.

9. The apparatus according to claim 1, wherein said controller is further configured to initiate a self recovery automatically in response to encountering one or more discrepancies in metadata stored in said memory.

10. The apparatus according to claim 1, wherein said apparatus is implemented as one or more integrated circuits.

11. A method for self recovery in a memory of an input/output device, comprising the steps of:

(A) reading information stored in a plurality of pages of said memory, wherein (i) said memory is nonvolatile, (ii) said information comprises a plurality of data units and a plurality of headers, (iii) each of said data units is associated with a respective identifier in an address space of said input/output device and a respective location in said memory, (iv) each of said data units has a respective one of said headers comprising said respective identifier, (v) each of said data units is associated with a respective one of a plurality of time stamps and (vi) multiple ones of said headers comprise ones of said time stamps;

(B) determining an order in which said data units were written to said memory based on said time stamps;

(C) locating based on said order (i) each last-written occurrence of said respective identifiers and (ii) said respective locations of said data units associated with said last-written occurrences; and

(D) rebuilding a map of said input/output device according to said respective locations of each of said last-written occurrence of each of said respective identifiers.

12. The method according to claim 11, wherein said input/output device is part of a solid-state drive.

13. The method according to claim 11, wherein said rebuilding comprises storing a respective length of each of said last-written occurrences of each of said respective identifiers in said map.

14. The method according to claim 13, wherein said rebuilding further comprises storing said respective lengths in said map.

15. The method according to claim 13, wherein said respective length of a first of said last-written occurrences differs from said respective length of a second of said last-written occurrences.

16. The method according to claim 11, wherein said determining, said locating, and said rebuilding are performed in response to a corruption of said map.

17. The method according to claim 11, further comprising the step of:

parsing at least some of said headers stored in a subset of said pages to determine data suitable to decrypt encrypted ones of said pages.

18. The methods according to claim 11, further comprising the step of:

initiating said self recovery in response to a signal received from a computer, wherein said map is rebuilt in said computer.

19. The methods according to claim 11, further comprising the step of:

initiating said self recovery automatically in response to encountering one or more discrepancies in metadata stored in said memory.

20. An apparatus comprising:

means for reading information stored in a plurality of pages of a memory, wherein (i) said memory is nonvolatile, (ii) said information comprises a plurality of data units and a plurality of headers, (iii) each of said data units is associated with a respective identifier in an address space of said apparatus and a respective location in said memory, (iv) each of said data units has a respective one of said headers comprising said respective identifier, (v) each of said data units is associated with a respective one of a plurality of time stamps and (vi) multiple ones of said headers comprise ones of said time stamps;

means for determining an order in which said data units were written to said memory based on said time stamps;

means for locating based on said order (i) each last-written occurrence of said respective identifiers and (ii) said respective locations of said data units associated with said last-written occurrences; and

means for rebuilding a map according to said respective locations of each of said last-written occurrence of each of said respective identifiers.