Methods and systems for storing data in a redundant manner on a plurality of storage units of a storage system

Patent metadata

Field	Value
Publication number	US-2016019114-A1
Application number	US-201414332282-A
Country	US
Kind code	A1
Filing date	Jul 15, 2014
Priority date	Jul 15, 2014
Publication date	Jan 21, 2016
Grant date	—

Abstract

Described herein are techniques for storing data in a redundant manner on a plurality of storage units of a storage system. While all of the storage units are operating without failure, only error-correction blocks are stored on a first one of the storage units, while a combination of data blocks and error-correction blocks are stored on a second one of the storage units. Upon failure of the second storage unit, one or more data blocks and one or more error-correction blocks formerly stored on the second storage unit are reconstructed, and the one or more reconstructed data blocks and the one or more reconstructed error-correction blocks are stored on the first storage unit.

First claim

What is claimed is:

1 . A method for a storage system having a plurality of storage units, the method comprising:
while all of the storage units are operating without failure, storing only error-correction blocks on a first one of the storage units and storing a combination of data blocks and error-correction blocks on a second one of the storage units; and upon failure of the second storage unit, (i) reconstructing one or more data blocks and one or more error-correction blocks formerly stored on the second storage unit, and (ii) storing the one or more reconstructed data blocks and the one or more reconstructed error-correction blocks on the first storage unit.

2 . The method of claim 1 , further comprising:
prior to storing the one or more reconstructed data blocks and one or more error-correction blocks on the first storage unit, backing up one or more of the error-correction blocks on the first storage unit on a persistent storage device.

3 . The method of claim 2 , wherein at least one of the reconstructed data blocks overwrites the one or more error-correction blocks on the first storage unit that have been backed up onto the persistent storage device.

4 . The method of claim 3 , wherein at least one of the error-correction blocks that is backed up belongs to a first stripe, and the at least one of the error-correction blocks that is backed up and belongs to the first stripe is overwritten by at least one reconstructed data block that belongs to a second stripe.

5 . The method of claim 2 , wherein at least one of the reconstructed error-correction blocks overwrites the one or more error-correction blocks on the first storage unit that have been backed up onto the persistent storage device.

6 . The method of claim 5 , wherein at least one of the error-correction blocks that is backed up belongs to a first stripe, and the at least one of the error-correction blocks that is backed up and belongs to the first stripe is overwritten by at least one reconstructed error-correction block that belongs to a second stripe.

7 . The method of claim 1 , wherein at least one of the reconstructed data blocks overwrites at least one of the error-correction blocks on the first storage unit.

8 . The method of claim 7 , wherein at least one of the error-correction blocks that is overwritten belongs to a first stripe, and the at least one of the error-correction blocks that is overwritten and belongs to the first stripe is overwritten by at least one reconstructed data block that belongs to a second stripe.

9 . The method of claim 1 , wherein at least one of the reconstructed error-correction blocks overwrites at least one of the error-correction blocks on the first storage unit.

10 . The method of claim 9 , wherein at least one of the error-correction blocks that is overwritten belongs to a first stripe, and the at least one of the error-correction blocks that is overwritten and belongs to the first stripe is overwritten by at least one reconstructed error-correction block that belongs to a second stripe.

11 . A storage system, comprising:
a plurality of storage units; a main memory; a processor communicatively coupled to the plurality of storage units and the main memory; and a set of instructions on the main memory that, when executed by the processor, cause the processor to: while all of the storage units are operating without failure, store only error-correction blocks on a first one of the storage units and store a combination of data blocks and error-correction blocks on a second one of the storage units; and upon failure of the second storage unit, (i) reconstruct one or more data blocks and one or more error-correction blocks formerly stored on the second storage unit, and (ii) store the one or more reconstructed data blocks and one or more reconstructed error-correction blocks on the first storage unit.

12 . The storage system of claim 11 , wherein at least one of the reconstructed data blocks overwrites at least one of the error-correction blocks on the first storage unit.

13 . The storage system of claim 12 , wherein at least one of the error-correction blocks that is overwritten belongs to a first stripe, and the at least one of the error-correction blocks that is overwritten and belongs to the first stripe is overwritten by at least one reconstructed data block that belongs to a second stripe.

14 . The storage system of claim 11 , wherein at least one of the reconstructed error-correction blocks overwrites at least one of the error-correction blocks on the first storage unit.

15 . The storage system of claim 14 , wherein at least one of the error-correction blocks that is overwritten belongs to a first stripe, and the at least one of the error-correction blocks that is overwritten and belongs to the first stripe is overwritten by at least one reconstructed error-correction block that belongs to a second stripe.

16 . A non-transitory machine-readable storage medium for a storage system having a plurality of storage units, a main memory, and a processor communicatively coupled to the plurality of storage units and the main memory, the non-transitory machine-readable storage medium comprising software instructions that, when executed by the processor, cause the processor to:
while all of the storage units are operating without failure, store only error-correction blocks on a first one of the storage units and store a combination of data blocks and error-correction blocks on a second one of the storage units; and upon failure of the second storage unit, (i) reconstruct one or more data blocks and one or more error-correction blocks formerly stored on the second storage unit, and (ii) store the one or more reconstructed data blocks and one or more reconstructed error-correction blocks on the first storage unit.

17 . The non-transitory machine-readable storage medium of claim 16 , wherein at least one of the reconstructed data blocks overwrites at least one of the error-correction blocks on the first storage unit.

18 . The non-transitory machine-readable storage medium of claim 17 , wherein at least one of the error-correction blocks that is overwritten belongs to a first stripe, and the at least one of the error-correction blocks that is overwritten and belongs to the first stripe is overwritten by at least one reconstructed data block that belongs to a second stripe.

19 . The non-transitory machine-readable storage medium of claim 16 , wherein at least one of the reconstructed error-correction blocks overwrites at least one of the error-correction blocks on the first storage unit.

20 . The non-transitory machine-readable storage medium of claim 19 , wherein at least one of the error-correction blocks that is overwritten belongs to a first stripe, and the at least one of the error-correction blocks that is overwritten and belongs to the first stripe is overwritten by at least one reconstructed error-correction block that belongs to a second stripe.

Assignees

• Nimble Storage Inc

Inventors

• Han Chunqi
• Nanduri Anil
• Vishnumolakala Murali Krishna

Classifications

• G06F11/1088 Primary

  Reconstruction on already foreseen single or plurality of spare disks · CPC title

• G06F11/1092

  Rebuilding, e.g. when physically replacing a failing disk · CPC title

• G06F11/1096

  Parity calculation or recalculation after configuration or reconfiguration of the system · CPC title

• G06F11/1076

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

• G06F11/1084

  Degraded mode, e.g. caused by single or multiple storage removals or disk failures · CPC title