Method and apparatus for redundant array of independent disks with raid metadata and sub-raid metadata stored using different raid algorithms

Patent metadata

Field	Value
Publication number	US-10324810-B2
Application number	US-201615272693-A
Country	US
Kind code	B2
Filing date	Sep 22, 2016
Priority date	Sep 25, 2015
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

The present disclosure provides a method and apparatus for a redundant array of independent disks, RAID. The method includes: dividing the RAID into a plurality of sub-RAIDs; generating sub-RAID metadata corresponding to each of the sub-RAIDs; and in response to a disk in the RAID being replaced, rebuilding data in a corresponding sub-RAID based on the sub-RAID metadata. The present disclosure further provides a computer readable storage medium and a storage system.

First claim

We claim:

1. A method for a redundant array of independent disks, RAID, comprising:
dividing the RAID into a plurality of sub-RAIDs, wherein the RAID is a parent and the plurality of sub-RAIDs are children of the parent;
generating sub-RAID metadata corresponding to each of the sub-RAIDs, wherein metadata of the parent RAID and the sub-RAID metadata of the children are stored in separate RAID storage devices using different RAID algorithms; and
in response to a disk in the RAID being replaced, rebuilding data in a corresponding sub-RAID based on the sub-RAID metadata.

2. The method according to claim 1 , wherein the sub-RAID metadata includes a rebuilding state, the method further comprising:
in response to a disk in the RAID being replaced, setting the rebuilding state to indicate that the disk needs to be rebuilt;
rebuilding the disk according to the indication of the rebuilding state; and
in response to completing the rebuilding of the disk, setting the rebuilding state to indicate that the disk does not need to be rebuilt.

3. The method according to claim 2 , wherein each disk in the RAID corresponds to one bit of the rebuilding state, the method further comprising: setting a bit of the rebuilding state corresponding to the disk to indicate whether the disk needs to be rebuilt.

4. The method according to claim 1 , wherein the sub-RAID metadata includes a rebuilding priority, the method further comprising: rebuilding data in the plurality of sub-RAIDs according to a priority order.

5. The method according to claim 4 , further comprising: generating RAID metadata corresponding to the RAID.

6. The method according to claim 5 , wherein the RAID metadata includes a disk signature, the disk signature including a disk identifier uniquely identifying a disk and a RAID identifier uniquely identifying a RAID.

7. The method according to claim 6 , further comprising:
in response to a disk in the RAID being replaced, determining whether a disk signature of a new disk exists in the RAID metadata;
if it is determined that the disk signature of the new disk exists in the RAID metadata, directly connecting the new disk into the RAID;
if it is determined that the disk signature of the new disk does not exist in the RAID metadata, updating the disk signature of the new disk with the RAID identifier of the RAID; and
storing the updated disk signature in the RAID metadata.

8. The method according to claim 5 , wherein the RAID metadata includes the number of sub-RAIDs that need to be rebuilt and a list of the sub-RAIDs that need to be rebuilt, the method further comprising: in response to completing the rebuilding of data in a sub-RAID, updating the number of sub-RAIDs that need to be rebuilt and the list of the sub-RAIDs that need to be rebuilt.

9. The method according to claim 5 , wherein the sub-RAID metadata and the RAID metadata are stored in storage external to the RAID.

10. The method according to claim 1 , further comprising:
when rebuilding of data in all the sub-RAIDs has not been completed and at least one disk in the RAID becomes unavailable, determining whether a rebuilding state in the sub-RAID metadata indicates existence of a disk that needs to be rebuilt;
if the rebuilding state in the sub-RAID metadata indicates that no disk needs to be rebuilt, recovering data in the sub-RAID; and
if the rebuilding state in the sub-RAID metadata indicates existence of a disk that needs to be rebuilt, labeling data in the sub-RAID as being lost.

11. An apparatus for a redundant array of independent disks (RAID), including one or more processors and one or more memories configured to perform operations, comprising:
dividing the RAID into a plurality of sub-RAIDs, wherein the RAID is a parent and the plurality of sub-RAIDs are children of the parent;
generating sub-RAID metadata corresponding to each of the sub-RAIDs, wherein metadata of the parent RAID and the sub-RAID metadata of the children are stored in separate RAID storage devices using different RAID algorithms; and
rebuilding, in response to a disk in the RAID being replaced, data in a corresponding sub-RAID based on the sub-RAID metadata.

12. The apparatus according to claim 11 , wherein the sub-RAID metadata includes a rebuilding state, the operations further comprising:
setting, in response to a disk in the RAID being replaced, the rebuilding state to indicate that the disk needs to be rebuilt;
wherein the disk that needs to be rebuilt is rebuilt according to the indication of the rebuilding state; and
in response to completing the rebuilding of the disk, setting the rebuilding state to indicate that the disk does not need to be rebuilt.

13. The apparatus according to claim 12 , wherein each disk in the RAID corresponds to one bit of the rebuilding state and wherein the operations further comprise setting a bit of the rebuilding state corresponding to the disk to indicate whether the disk needs to be rebuilt.

14. The apparatus according to claim 11 , wherein the sub-RAID metadata includes a rebuilding priority and wherein the operations further comprise rebuilding data in the plurality of sub-RAIDs according to a priority order.

15. The apparatus according to claim 14 , wherein the operations further comprise generating RAID metadata corresponding to the RAID.

16. The apparatus according to claim 15 , wherein the RAID metadata includes a disk signature, the disk signature including a disk identifier uniquely identifying a disk and a RAID identifier uniquely identifying a RAID.

17. The apparatus according to claim 16 , wherein the operations further comprise:
determining, in response to a disk in the RAID being replaced, whether a disk signature of a new disk exists in the RAID metadata;
connecting, if it is determined that the disk signature of the new disk exists in the RAID metadata, directly the new disk into the RAID; and
updating, if it is determined that the disk signature of the new disk does not exist in the RAID metadata, the disk signature of the new disk with the RAID identifier of the RAID, and storing the updated disk signature in the RAID metadata.

18. The apparatus according to claim 15 , wherein the RAID metadata includes the number of sub-RAIDs that need to be rebuilt and a list of the sub-RAIDs that need to be rebuilt, and wherein the operations further comprise updating, in response to completing the rebuilding of data in a sub-RAID, the number of sub-RAIDs that need to be rebuilt and the list of the sub-RAIDs that need to the rebuilt.

19. The apparatus according to claim 15 , wherein the sub-RAID metadata and the RAID metadata are stored in storage external to the RAID.

20. The apparatus according to claim 11 , wherein the operations further comprise determining, when rebuilding of data in all the sub-RAIDs has not been completed and at least one disk in the RAID becomes unavailable, whether a rebuilding state in the sub-RAID metadata indicates existence of a disk that needs to be rebuilt; the operations further comprising:
recovering, if the rebuilding state in the sub-RAID metadata indicates that no disk needs to be rebuilt, data in the sub-RAID; and
labeling, if the rebuilding state in the sub-RAID metadata indicates existence of a disk that needs to be rebuilt, data in the sub-RAID as being lost.

Assignees

• Emc Ip Holding Co Llc

Inventors

• Gao Hongpo
• Gao Jian
• Xiao Huibing
• Dong Jibing
• Han Geng

Classifications

• G06F2201/805

  Real-time · CPC title

• G06F11/1662 Primary

  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 title

• G06F11/2056

  by mirroring · CPC title

• G06F11/2053

  where persistent mass storage functionality or persistent mass storage control functionality is redundant (error detection or correction in information storage based on relative movement between record carrier and transducer G11B20/18) · CPC title

• G06F11/1076

  Parity data used in redundant arrays of independent storages, e.g. in RAID systems · CPC title