METHODS AND SYSTEMS FOR STORING DATA IN A REDUNDANT MANNER ON A PLURALITY OF STORAGE UNITS OF A STORAGE SYSTEM

• US 20160019114A1
• Filed: 07/15/2014
• Published: 01/21/2016
• Est. Priority Date: 07/15/2014
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Nimble Storage Inc (Hewlett-Packard Enterprise Company)
• Inventors: Han, Chunqi, Nanduri, Anil, Vishnumolakala, Murali Krishna
• Granted Patent: US 9,563,509 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1084 Degraded mode, e.g. caused by single or multiple storage removals or disk failures
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/1096 Parity calculation or recalculation after configuration or reconfiguration of the system

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.

Claims

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.