Method and system for replicating and using grid level metadata in a storage system

• US 10,466,913 B2
• Filed: 04/29/2015
• Issued: 11/05/2019
• Est. Priority Date: 04/29/2015
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Bonwick, Jeffrey S.
• Primary Examiner(s): Khan, Masud K
• Application Number:
  US14/699,594
• Publication Number:
  US 20160320986A1
• Time in Patent Office: 1,651 Days
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

In general, embodiments of the technology relate to a method and system protecting data in persistent storage. More specifically, various embodiments of the technology relate to using different replication schemes to protect different types of data within the persistent storage.

Claims

1. A method for storing data comprising:

(a) generating a first plurality of labels each comprising a first program/erase (P/E) count for a first zone in a RAID grid and first bad location information for the first zone, wherein the first zone comprises a first set of RAID grid locations and a second set of RAID grid locations, wherein the first zone is divided into a first side and a second side, wherein the first side comprises the first set of RAID grid locations and the second side comprises the second set of RAID grid locations, wherein the first set of RAID grid locations corresponds to at least a page in a first storage device of a storage array and a second page in a second storage device of the storage array;

(b) erasing each of the first set of RAID grid locations;

(c) writing one of the first plurality of labels to at least one page in each of the first set of RAID grid locations;

(d) erasing each of the second set of RAID grid locations, wherein (b) and (c) are performed before (d);

(e) generating a second plurality of labels each comprising a second program/erase (P/E) count for the first zone in the RAID grid and second bad location information for the first zone, wherein content in the second plurality of labels is based, at least in part, on (b) and (d);

(f) writing one of the second plurality of labels to at least one page in each of the second set of RAID grid locations; and

(g) writing user data to each of the first set of RAID grid locations and each of the second set of RAID grid locations, wherein the user data comprises client data, block-level metadata, and parity data, wherein after (g), at least one of the first set of RAID grid locations comprises a block, wherein at least one page in the block comprises user data and at least one page in the block comprises one of the first plurality of labels.

2. The method of claim 1, further comprising:

(h) generating a third plurality of labels each comprising a third P/E count for a second zone in the RAID grid and third bad location information for the second zone;

(i) erasing each of a third set of RAID grid locations, wherein each of the third set of RAID grid locations comprises a block associated with a first side of the second zone;

(j) writing one of the third plurality of labels to each of the third set of RAID grid locations;

(k) erasing each of a fourth set of RAID grid locations, wherein each of the fourth set of RAID grid locations comprises a block associated with a second side of the second zone;

(l) generating a fourth plurality of labels each comprising a fourth P/E count for the second zone in the RAID grid and fourth bad location information for the second zone;

(m) writing one of the fourth plurality of labels to each of the fourth set of RAID grid locations; and

(n) writing user data to each of the third set of RAID grid location and each of the fourth set of RAID grid locations.

3. The method of claim 2, wherein each of the first plurality of labels further comprises a timestamp and wherein each of the third plurality of labels further comprises the timestamp.

4. The method of claim 1, wherein the parity value comprises at least one selected from a group consisting of a P parity value, a Q parity value, and an intersection parity value.

5. The method of claim 1, wherein the user data in the RAID grid is protected by a RAID-scheme, wherein the first plurality of labels in the RAID grid are protected by a replication-scheme.

6. The method of claim 1, wherein the second bad location information for the first zone comprises at least one selected from a group consisting of bad storage module information, bad block information, and bad page information.

7. The method of claim 1, wherein the second bad location information is different than the first bad location information.

8. The method of claim 1, wherein (c) and (f) are performed before (g).

9. The method of claim 1, wherein each of the first plurality of labels comprises a grid geometry for the RAID grid and wherein the grid geometry comprises a parity location in the RAID grid.

10. The method of claim 9, wherein each of the second plurality of labels comprises the grid geometry for the RAID grid.

11. The method of claim 1, wherein the first set of RAID grid locations are a portion of a RAID grid and the second set of RAID grid locations are a portion of the RAID grid.

12. The method of claim 1, wherein the second set of RAID grid locations correspond to at least a page in a third storage device of the storage array and a page in a fourth storage device of the storage array.

13. A non-transitory computer readable medium comprising computer readable program code, which when executed by a computer processor enables the computer processor to:

(a) generate a first plurality of labels each comprising a first program/erase (P/E) count for a first zone in a RAID grid and first bad location information for the first zone, wherein the first zone comprises a first set of RAID grid locations and a second set of RAID grid locations, wherein the first zone is divided into a first side and a second side, wherein the first side comprises the first set of RAID grid locations and the second side comprises the second set of RAID grid locations, wherein the first set of RAID grid locations corresponds to at least a page in a first storage device of a storage array and a second page in a second storage device of the storage array;

(b) erase each of the first set of RAID grid locations;

(c) write one of the first plurality of labels to at least one page in each of the first set of RAID grid locations;

(d) erase each of the second set of RAID grid locations, wherein (b) and (c) are performed before (d);

(e) generate a second plurality of labels each comprising a second program/erase (P/E) count for the first zone in the RAID grid and second bad location information for the first zone, wherein content in the second plurality of labels is based, at least in part, on (b) and (d);

(f) write one of the second plurality of labels to at least one page in each of the second set of RAID grid locations; and

(g) write user data to each of the first set of RAID grid locations and each of the second set of RAID grid locations, wherein the user data comprises client data, block-level metadata, and parity data, wherein after (g), at least one of the first set of RAID grid locations comprises a block, wherein at least one page in the block comprises user data and at least one page in the block comprises one of the first plurality of labels.

14. The non-transitory computer readable medium of claim 13, further comprising computer readable program code, which when executed by the computer processor enables the computer processor to:

(h) generate a third plurality of labels each comprising a third P/E count for a second zone in the RAID grid and third bad location information for the second zone;

(i) erase each of a third set of RAID grid locations, wherein each of the third set of RAID grid locations comprises a block associated with a first side of the second zone;

(j) write one of the third plurality of labels to each of the third set of RAID grid locations;

(k) erase each of a fourth set of RAID grid locations, wherein each of the fourth set of RAID grid locations comprises a block associated with a second side of the second zone;

(l) generate a fourth plurality of labels each comprising a fourth P/E count for the second zone in the RAID grid and fourth bad location information for the second zone;

(m) write one of the fourth plurality of labels to each of the fourth set of RAID grid locations; and

(n) write second user data to each of the third set of RAID grid location and each of the fourth set of RAID grid locations.

15. The non-transitory computer readable medium of claim 13, wherein each of the first plurality of labels further comprises a timestamp and wherein each of the third plurality of labels further comprise the timestamp.

16. The non-transitory computer readable medium of claim 13, wherein the parity value comprises at least one selected from a group consisting of a P parity value, a Q parity value, and an intersection parity value.

17. The non-transitory computer readable medium of claim 13, wherein the second bad location information is determined, at least in part, using a result of (b) and (d) and wherein the second bad location information for the first zone comprises at least one selected from a group consisting of bad storage module information, bad block information, and bad page information.

18. The non-transitory computer readable medium of claim 13, wherein (c) and (f) are performed before (g).

19. The non-transitory computer readable medium of claim 13, wherein each of the first plurality of labels comprises a grid geometry for the RAID grid, wherein each of the second plurality of labels comprises the grid geometry for the RAID grid, and wherein the grid geometry comprises a parity location in the RAID grid.

20. A system, comprising:

a controller;

a non-transitory medium operatively connected to the controller;

persistent storage operatively connected to the controller and comprising a plurality of storage modules, wherein each of the plurality of storage modules comprises solid state memory;

wherein the non-transitory computer readable medium comprises instructions which when executed by the controller performs a method, the method comprising;

(a) generating a first plurality of labels each comprising a first program/erase (P/E) count for a first zone in a RAID grid and first bad location information for the first zone,

wherein the first zone comprises a first set of RAID grid locations and a second set of RAID grid locations, wherein the first zone is divided into a first side and a second side, wherein the first side comprises the first set of RAID grid locations and the second side comprises the second set of RAID grid locations, wherein the first set of RAID grid locations corresponds to at least a page in a first storage device of a storage array and a second page in a second storage device of the storage array;

(b) erasing each of the first set of RAID grid locations;

(c) writing one of the first plurality of labels to at least one of each of the first set of RAID grid locations;

(d) erasing each of a second set of RAID grid locations, wherein (b) and (c) are performed before (d);

(e) generating a second plurality of labels each comprising a second program/erase (P/E) count for the first zone in the RAID grid and second bad location information for the first zone, wherein content in the second plurality of labels is based, at least in part, on (b) and (d);

(f) writing one of the second plurality of labels to at least one page in each of the second set of RAID grid locations; and

(g) writing user data to each of the first set of RAID grid locations and each of the second set of RAID grid locations, wherein the user data comprises client data, block-level metadata, and parity data, wherein after (g), at least one of the first set of RAID grid locations comprises a block, wherein at least one page in the block comprises user data and at least one page in the block comprises one of the first plurality of labels, and wherein each of the blocks is located on one of the plurality of storage modules.