DATA STORAGE SYSTEM EMPLOYING A HOT SPARE TO PROACTIVELY STORE ARRAY DATA IN ABSENCE OF A FAILURE OR PRE-FAILURE EVENT

• US 20180165169A1
• Filed: 12/12/2016
• Published: 06/14/2018
• Est. Priority Date: 12/12/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: CAMP, CHARLES J., SHUHATOVICH, LEV M.
• Granted Patent: US 10,241,877 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1088 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 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2087 with a common controller
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 11/3041 where the computing system component is an input/output interface interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units G06F13/00
• CPC Class Codes: G06F 2201/88 Monitoring involving counting
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

A data storage system includes a controller, a hot spare storage device and a plurality of primary storage devices. The controller utilizes the hot spare storage device to mirror only a subset of each stripe of logical pages written across the data storage array, where the subset includes a logical page determined by a write input/output operation (IOP) policy. In response to receipt of a write IOP, the controller writes a stripe including a plurality of logical data pages and a logical data protection page across the plurality of primary storage devices and mirrors the logical page determined by the write IOP policy on the hot spare storage device. In response to a failure of a storage device among the plurality of primary storage devices, contents of the failed storage device not already mirrored on the hot spare storage device are rebuilt on the hot spare storage device.

Claims

1. A method in a data storage system including a controller, a hot spare storage device and a plurality of primary storage devices across which a data storage array is striped, the method comprising:

the controller controlling storage of data on the hot spare storage device such that the hot spare storage device mirrors only a subset of each data stripe written across the primary storage devices, wherein the subset includes a logical page determined by a write input/output operation (IOP) policy;

in response to receipt of a write IOP of a host, the controller writing a stripe including a plurality of logical data pages and a logical data protection page across the plurality of primary storage devices and mirroring the logical page from the stripe onto the hot spare storage device as determined by the write IOP policy; and

in response to a failure of a failed storage device among the plurality of primary storage devices, rebuilding, on the hot spare storage device, contents of the failed storage device not already mirrored on the hot spare storage device.

2. The method of claim 1, wherein:

the plurality of primary storage devices includes a particular primary storage device; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the logical page written to the particular primary storage device.

3. The method of claim 1, wherein:

the write IOP policy selects the logical page mirrored on the hot spare storage device such that approximately a same amount of data from each of the plurality of primary storage devices is mirrored to the hot spare storage device.

4. The method of claim 1, wherein:

the method further comprises the controller determining a least healthy one of the plurality of primary storage devices; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the logical page written to the least healthy one of the plurality of primary storage devices.

5. The method of claim 1, wherein:

the method further comprises the controller determining a coldest data page among the plurality of logical data pages that is associated with a logical address having a lowest relative write frequency; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the coldest data page.

6. The method of claim 1, wherein the rebuilding further comprises:

retaining on the hot spare storage device logical pages mirrored from the failed storage device; and

removing from the hot spare storage device any logical pages mirrored from any primary storage device other than the failed storage device.

7. A data storage system, comprising:

a controller configured to be coupled to a hot spare storage device and to a plurality of primary storage devices across which a data storage array is striped, wherein the controller is configured to perform;

the controller controlling data storage on the hot spare storage device such that the hot spare storage device mirrors only a subset of each stripe of logical pages written across the data storage array, wherein the subset includes a logical page determined by a write input/output operation (IOP) policy;

in response to receipt of a write IOP of a host, the controller writing a stripe including a plurality of logical data pages and a logical data protection page across the plurality of primary storage devices and mirroring the logical page from the stripe determined by the write IOP policy on the hot spare storage device; and

in response to a failure of a failed storage device among the plurality of primary storage devices, rebuilding, on the hot spare storage device, contents of the failed storage device not already mirrored on the hot spare storage device.

8. The data storage system of claim 7, wherein:

the plurality of primary storage devices includes a particular primary storage device; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the logical page written to the particular primary storage device.

9. The data storage system of claim 7, wherein:

the controller, based on the write IOP policy, selects the logical page mirrored on the hot spare storage device such that approximately a same amount of data from each of the plurality of primary storage devices is mirrored to the hot spare storage device.

10. The data storage system of claim 7, wherein:

the controller is further configured to determine a least healthy one of the plurality of primary storage devices; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the logical page written to the least healthy one of the plurality of primary storage devices.

11. The data storage system of claim 7, wherein:

the controller is further configured to determine a coldest data page among the plurality of logical data pages that is associated with a logical address having a lowest relative write frequency; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the coldest data page.

12. The data storage system of claim 7, wherein the rebuilding includes:

the controller retaining on the hot spare storage device logical pages mirrored from the failed storage device; and

the controller removing from the hot spare storage device any logical pages mirrored from any primary storage device other than the failed storage device.

13. The data storage system of claim 7, and further comprising the hot spare storage device and the plurality of primary storage devices.

14. A program product, comprising:

a storage device; and

program code stored in the storage device, wherein the program code, when executed by a controller configured to be coupled to a hot spare storage device and to a plurality of primary storage devices across which a data storage array is striped, causes the controller to perform;

controlling data storage on the hot spare storage device such that the hot spare storage device mirrors only a subset of each stripe of logical pages written across the data storage array, wherein the subset includes a logical page determined by a write input/output operation (IOP) policy;

in response to receipt of a write IOP of a host, the controller writing a stripe including a plurality of logical data pages and a logical data protection page across the plurality of primary storage devices and mirroring the logical page from the stripe determined by the write IOP policy on the hot spare storage device; and

in response to a failure of a failed storage device among the plurality of primary storage devices, rebuilding, on the hot spare storage device, contents of the failed storage device not already mirrored on the hot spare storage device.

15. The program product of claim 14, wherein:

the plurality of primary storage devices includes a particular primary storage device; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the logical page written to the particular primary storage device.

16. The program product of claim 14, wherein:

the program code causes the controller, based on the write IOP policy, to select the logical page mirrored on the hot spare storage device such that approximately a same amount of data from each of the plurality of primary storage devices is stored on the hot spare storage device.

17. The program product of claim 14, wherein:

the program code causes the controller to determine a least healthy one of the plurality of primary storage devices; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the logical page written to the least healthy one of the plurality of primary storage devices.

18. The program product of claim 14, wherein:

the program code causes the controller to determine a coldest data page among the plurality of logical data pages that is associated with a logical address having a lowest relative write frequency; and

the logical page determined by the write IOP policy to be mirrored on the hot spare storage device is the coldest data page.

19. The program product of claim 14, wherein the rebuilding includes:

the controller retaining on the hot spare storage device logical pages mirrored from the failed storage device; and

the controller removing from the hot spare storage device any logical pages mirrored from any primary storage device other than the failed storage device.