FAST DATA RECOVERY FROM HDD FAILURE

• US 20110126083A1
• Filed: 02/01/2011
• Published: 05/26/2011
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: KAWAGUCHI, Tomohiro
• Granted Patent: US 8,234,519 B2
• Time in Patent Office: Days
• US Class Current: 714/770
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk

Abstract

A storage system comprises a first storage device having a first plurality of hard disk drives and a first controller. The first controller stores data in the first plurality of hard disk drives by stripes. Each stripe includes M data and N parity data allocated to M+N hard disk drives of the first plurality of hard disk drives. A first hard disk drive includes data or parity data of both a first stripe of the stripes and a second stripe of the stripes, while a second hard disk drive includes data or parity data of only one of the first stripe or the second stripe. During data recovery involving failure of one of the first plurality of hard disk drives, the data in the failed hard disk drive is recovered for each stripe by calculation using data and parity data in other hard disk drives for each stripe.

Claims

1. A storage system comprising:

a first storage device having a plurality of hard disk drives and a first controller controlling the first plurality of hard disk drives;

wherein the first controller stores data in the first plurality of hard disk drives by stripes, the hard disk drives each include a plurality of parcels and the parcels each include a plurality of stripes, each stripe includes M data and N parity data, where M and N are integers, and the first controller calculates for each stripe the N parity data using the M data,

wherein the M data and N parity data of the each stripe are allocated to M+N hard disk drives of the first plurality of hard disk drives,

wherein a first hard disk drive of the first plurality of hard disk drives includes data or parity data of both a first stripe of the stripes and a second stripe of the stripes, while a second hard disk drive of the first plurality of hard disk drives includes data or parity data of only one of the first stripe of the stripes or the second stripe of the stripes,

wherein during data recovery involving failure of one of the first plurality of hard disk drives as a failed hard disk drive, the first controller makes an allocation area based on the parcel, and copies data from the failed hard disk drive to the allocation area.

2. A storage system according to claim 1,

wherein the first controller changes a mapping information from an area of the failed hard disk drive to the allocation area.

3. A storage system according to claim 1,

wherein the second hard disk drive of the first plurality of hard disk drives includes data or parity data of the first stripe of the stripes,

wherein a third hard disk drive of the first plurality of hard disk drives includes data or parity data of the second stripe of the stripes and does not include data or parity data of the first stripe of the stripes.

4. A storage system according to claim 3,

wherein the M is 3 and the N is 1,

wherein the number of the first plurality of hard disk drives is a multiple of four,

wherein data and parity data of the first stripe are included in the first and second hard disk drives of the first plurality of hard disk drives and in fourth and fifth hard disk drives of the first plurality of hard disk drives,

wherein data and parity data of the second stripe are included in the first, third, fourth, fifth hard disk drives of the first plurality of hard disk drives.

5. A storage system according to claim 3, further comprising:

a second storage device having a second plurality of hard disk drives and a second controller controlling the second plurality of hard disk drives;

wherein the data stored by the first controller is received from the second storage device,

wherein the first controller includes a plurality of processors,

wherein the second hard disk drive and the third hard disk drive are accessed by different processors of the plurality of processors concurrently when data is migrated from the second storage device to the first storage device.

6. A storage system according to claim 3, further comprising;

a capacity pool volume having unallocated hard disk drives of the first plurality of the hard disk drives,

wherein the stripes are allocated from the capacity pool volume.

7. A storage system according to claim 6, further comprising:

a second storage device having a second plurality of hard disk drives and a second controller controlling the second plurality of hard disk drives;

wherein the allocation of each stripe is conducted in response to receiving the data from the second storage device.

8. A storage system according to claim 3,

wherein the N parity data of each stripe are coupled to the first controller via different buses.

9. A storage system according to claim 1, further comprising:

a second storage device having a second plurality of hard disk drives and a second controller controlling the second plurality of hard disk drives;

wherein the data stored by the first controller is received from the second storage device,

wherein data and parity data of the first and second stripes are processed in parallel by the first controller.

10. A storage system according to claim 1,

wherein the first controller includes a table including information of allocation of the each stripe to the first plurality of hard disk drives.

11. A storage system according to claim 1,

wherein the M is 6 and the N is 2,

wherein the number of the first plurality of hard disk drives is a multiple of eight, and

wherein in case of reading data from one of the stripes including a failure of one of the first plurality of hard disk drives, the first controller is controlled to access only seven hard disk drives of the first plurality of hard disk drives without access to the failed hard disk drive.

12. A storage system according to claim 11, further comprising;

a capacity pool volume having unallocated hard disk drives of the first plurality of the hard disk drives,

wherein the stripes are allocated from the capacity pool volume.

13. In a storage system which includes a first storage device having a first plurality of hard disk drives and a first controller controlling the first plurality of hard disk drives, a method of data recovery comprising:

storing data in the first plurality of hard disk drives of the first controller by stripes, the hard disk drives each including a plurality of parcels and the parcels each including a plurality of stripes, each stripe including M data and N parity data, where M and N are integers, and the first controller calculates for each stripe the N parity data using the M data;

allocating the M data and N parity data of the each stripe to M+N hard disk drives of the first plurality of hard disk drives, wherein a first hard disk drive of the first plurality of hard disk drives includes data or parity data of both a first stripe of the stripes and a second stripe of the stripes, while a second hard disk drive of the first plurality of hard disk drives includes data or parity data of only one of the first stripe of the stripes or the second stripe of the stripes; and

during data recovery involving failure of one of the first plurality of hard disk drives as a failed hard disk drive, making an allocation area based on the parcel, and copying data from the failed hard disk drive to the allocation area.

14. A method according to claim 13, further comprising:

changing a mapping information from an area of the failed hard disk drive to the allocation area.

15. A method according to claim 13,

wherein the second hard disk drive of the first plurality of hard disk drives includes data or parity data of the first stripe of the stripes,

wherein a third hard disk drive of the first plurality of hard disk drives includes data or parity data of the second stripe of the stripes and does not include data or parity data of the first stripe of the stripes.

16. A method according to claim 15,

wherein the M is 3 and the N is 1,

wherein the number of the first plurality of hard disk drives is a multiple of four,

wherein data and parity data of the first stripe are included in the first and second hard disk drives of the first plurality of hard disk drives and fourth and fifth hard disk drives of the first plurality of hard disk drives,

wherein data and parity data of the second stripe are included in the first, third, fourth, fifth hard disk drives of the first plurality of hard disk drives.

17. A method according to claim 15, wherein the first storage device further includes a capacity pool volume having unallocated hard disk drives of the first plurality of the second hard disk drives, wherein the stripes are each allocated from the capacity pool volume, and wherein the storage system further includes a second storage device having a second plurality of hard disk drives and a second controller controlling the plurality of hard disk drives, the method further comprising:

conducting the allocation of each stripe in response to receiving the data from the second storage device.

18. A method according to claim 13, wherein the M is 6 and the N is 2, and wherein the number of the first plurality of hard disk drives is a multiple of eight, the method further comprising:

in case of reading data from one of the stripes including a failure of one of the first plurality of hard disk drives, controlling the first controller to access only seven hard disk drives of the first plurality of hard disk drives without access to the failed hard disk drive.

19. A method according to claim 18, wherein the first storage device further includes a capacity pool volume having unallocated hard disk drives of the first plurality of the hard disk drives, the method further comprising:

allocating each the stripes from the capacity pool volume.

20. In a storage system which includes a first storage device having a first plurality of hard disk drives and a first controller controlling the first plurality of hard disk drives, a computer-readable medium storing a plurality of instructions for controlling a data processor to perform data recovery comprising:

instructions that cause the data processor to store data in the first plurality of hard disk drives of the first controller by stripes, the hard disk drives each including a plurality of parcels and the parcels each including a plurality of stripes, each stripe including M data and N parity data, where M and N are integers, and the first controller calculates for each stripe the N parity data using the M data;

instructions that cause the data processor to allocate the M data and N parity data of the each stripe to M+N hard disk drives of the first plurality of hard disk drives, wherein a first hard disk drive of the first plurality of hard disk drives includes data or parity data of both a first stripe of the stripes and a second stripe of the stripes, while a second hard disk drive of the first plurality of hard disk drives includes data or parity data of only one of the first stripe of the stripes or the second stripe of the stripes; and

instructions that cause the data processor, during data recovery involving failure of one of the first plurality of hard disk drives as a failed hard disk drive, to make an allocation area based on the parcel, and copy data from the failed hard disk drive to the allocation area.