Data recovery for failed memory device of memory device array

• US 9,021,335 B2
• Filed: 10/14/2013
• Issued: 04/28/2015
• Est. Priority Date: 04/22/2009
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Goel, Atul
• Primary Examiner(s): Leibovich, Yair
• Application Number:
  US14/053,060
• Publication Number:
  US 20140040661A1
• Time in Patent Office: 561 Days
• Field of Search: 714/770, 714/6.1, 714/800, 711/162
• US Class Current: 714/770
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G11C 7/1006 Data managing, e.g. manipulating data before writing or reading out, data bus switches or control circuits therefor

Abstract

Some aspects of the disclosure relate to a data storage system that includes multiple memory device storage devices. If a memory device of a memory device array fails within a first data storage device, some portions of the lost or corrupted data from the failed memory device are recovered by reading them from a second data storage device. Other portions of the lost or corrupted data from the failed memory device are recovered from parity information in the first data storage device.

Claims

1. A method for recovering lost data in a data storage system, comprising:

identifying failure of a memory device of a first data storage device within a data storage system, the failure resulting in a data loss of a data block stored within the memory device;

analyzing a logical address of a metadata unit associated with a physical address range in which the data block is stored to determine an arrangement of a first copied instance of the data block within the data storage system;

selectively retrieving a first portion of the data block, according to the arrangement, by reading at least part of the first copied instance of the data block from a second data storage device within the data storage system;

selectively recovering a second portion of the data block from parity information in the first data storage device; and

recovering the data block based upon the first portion and the second portion to create a recovered data block comprising the first portion retrieved from the second data storage device and the second portion reconstructed from the parity information in the first data storage device.

2. The method of claim 1, the logical address referencing the data block within the first data storage device.

3. The method of claim 1, the logical address referencing the first copied instance of the data block within the second data storage device.

4. The method of claim 1, the metadata unit comprising a consistency point count corresponding to a checkpoint number at which an instance of the data block was written.

5. The method of claim 1, the metadata unit comprising a generation ID identifying a physical block associated with the data block.

6. The method of claim 1, the identifying comprising:

responsive to determining that the metadata unit is lost based upon the failure of the memory device, recovering the metadata unit from a non-failed memory device.

7. The method of claim 1, the identifying comprising:

responsive to determining that the metadata unit is lost based upon the failure of the memory device, recovering the metadata unit as a recovered metadata unit using at least one of a parity block or a second metadata unit.

8. The method of claim 7, comprising:

receiving the recovered metadata unit from a memory device array controller.

9. The method of claim 1, the data storage system partitioned into a plurality of metadata zones and a plurality of data zones, a first metadata zone comprising the metadata unit and a first data zone comprising the data block.

10. The method of claim 1, comprising:

verifying that a second signature identifier of the first copied instance of the data block corresponds to a first signature identifier for the data block, the first signature identifier specified within the metadata unit.

11. The method of claim 1, the parity information extracted from a parity data block within a parity memory device of the data storage system.

12. The method of claim 1, the parity information interleaved, as one or more parity blocks, with data blocks of the first data storage device.

13. A system for recovering lost data in a data storage system, comprising:

one or more processors; and

memory comprising instructions that when executed by at least one of the one or more processors implement at least some of;

a data component configured to;

identify failure of a memory device of a first data storage device within a data storage system, the failure resulting in a data loss of a data block stored within the memory device;

analyze a logical address of a metadata unit associated with a physical address range in which the data block is stored to determine an arrangement of a first copied instance of the data block within the data storage system;

selectively retrieve a first portion of the data block, according to the arrangement, by reading at least part of the first copied instance of the data block from a second data storage device within the data storage system;

selectively recover a second portion of the data block from parity information in the first data storage device; and

recover the data block based upon the first portion and the second portion to create a recovered data block comprising the first portion retrieved from the second data storage device and the second portion reconstructed from the parity information in the first data storage device.

14. The system of claim 13, the logical address referencing the data block within the first data storage device.

15. The system of claim 13, the logical address referencing the first copied instance of the data block within the second data storage device.

16. The system of claim 13, the metadata unit comprising a consistency point count corresponding to a checkpoint number at which an instance of the data block was written.

17. The system of claim 13, the metadata unit comprising a generation ID identifying a physical block associated with the data block.

18. The system of claim 13, the data component configured to:

responsive to determining that the metadata unit is lost based upon the failure of the memory device, recover the metadata unit from a non-failed memory device.

19. The system of claim 13, the data component configured to:

responsive to determining that the metadata unit is lost based upon the failure of the memory device, recover the metadata unit as a recovered metadata unit using at least one of a parity block or a second metadata unit.

20. A non-transitory computer readable medium comprising instructions which when executed perform a method for recovering lost data in a data storage system, comprising:

identifying failure of a memory device of a first data storage device within a data storage system, the failure resulting in a data loss of a data block stored within the memory device;

analyzing a logical address of a metadata unit associated with a physical address range in which the data block is stored to determine an arrangement of a first copied instance of the data block within the data storage system;

selectively retrieving a first portion of the data block, according to the arrangement, by reading at least part of the first copied instance of the data block from a second data storage device within the data storage system;

selectively recovering a second portion of the data block from parity information in the first data storage device; and

recovering the data block based upon the first portion and the second portion to create a recovered data block comprising the first portion retrieved from the second data storage device and the second portion reconstructed from the parity information in the first data storage device.