STORAGE CONTROL APPARATUS AND STORAGE CONTROL APPARATUS CONTROL METHOD

• US 20130055013A1
• Filed: 08/29/2011
• Published: 02/28/2013
• Est. Priority Date: 08/29/2011
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Seki, Toshiya
• Granted Patent: US 8,719,620 B2
• Time in Patent Office: Days
• US Class Current: 714/6.24
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk

Abstract

The present invention reduces the amount of rebuild processing and executes a rebuild process efficiently. Multiple storage devices configure a parity group. Of the multiple storage devices, a prescribed storage device in which a failure has occurred is blocked. Each storage device stores management information. The management information manages from among the storage areas of the storage device a prescribed area having data from a higher-level apparatus. A controller determines whether a storage area of the prescribed storage device is the prescribed area based on the management information, and executes a rebuild process with respect to the area determined to be the prescribed area.

Claims

1. A storage control apparatus used by a higher-level apparatus, comprising:

a controller, and multiple storage devices controlled by this controller, wherein

the multiple storage devices configure a parity group, which enables data restoration by parity,

the storage control apparatus further comprising;

a blocking process part for blocking a prescribed storage device from among the multiple storage devices;

a management information storage part for storing management information for managing for each of the storage devices a prescribed area having data from a higher-level apparatus from among the storage areas of the respective multiple storage devices;

a determination part for determining whether a storage area of the prescribed storage device is the prescribed area based on the management information; and

a rebuild control part for executing a rebuild process with respect to an area determined to be the prescribed area from among the storage areas of the prescribed storage device.

2. A storage control apparatus according to claim 1, wherein the management information storage part is disposed in each of the multiple storage devices.

3. A storage control apparatus according to claim 2, wherein

the determination part determines for each stripe set inside the parity group whether a storage area of the prescribed storage device is a data area or a parity area,

in a case where the storage area is determined to be a data area, acquires management information related to the parity area corresponding to this data area from the management information storage part, and determines whether the data area is the prescribed area based on the management information related to the parity area and a prescribed determination criterion, and

in a case where the storage area is determined to be a parity area, acquires management information related to the data areas corresponding to this parity area from the management information storage part, and determines whether the parity area is the prescribed area based on the management information related to the data areas and a prescribed determination criterion.

4. A storage control apparatus according to claim 3, wherein

the management information, which is managed by the management information storage part, manages, for each area of a prescribed size, a storage area of the storage device, with a first value denoting the number of data writes at production being associated with a second value denoting the current number of data writes, and

based on the prescribed determination criterion, a determination is made that an area for which the first value and the second value do not match is the prescribed area.

5. A storage control apparatus according to claim 4, wherein

the management information further manages, in association with the second value, a third value for denoting whether or not data of the prescribed size area has been erased, and

based on the prescribed determination criterion, in a case where the third value does not denote a data erase, a determination is made that an area for which the first value and the second value do not match is the prescribed area.

6. A storage control apparatus according to claim 5, wherein

the third value is configured as a most significant bit of the second value,

in a case where data in the prescribed size area has been erased, the most significant bit is set to ON, and

in a case where data is written in the prescribed size area, the most significant bit is set to OFF.

7. A storage control apparatus according to claim 1, wherein the management information storage part is disposed inside the controller, and manages the presence or absence of the prescribed area with respect to the multiple storage devices.

8. A storage control apparatus according to claim 7, wherein the management information, which is managed by the management information storage part, manages for each stripe set of the parity group whether data has been written from the higher-level apparatus.

9. A method for controlling a storage control apparatus used by a higher-level apparatus, wherein

the storage control apparatus has a controller, and multiple storage devices controlled by the controller,

the multiple storage devices configure a parity group, which enables data restoration by parity, and

the multiple storage devices further store management information, which denotes whether there is a prescribed area that stores data written from the higher-level apparatus, for each of multiple second areas, which configure a first storage area of the respective storage devices, and wherein

the controller carries out:

a failure detection step of detecting whether a storage device in which a failure has occurred exists among the multiple storage devices;

a blocking step of blocking a failed storage apparatus in a case where a storage device in which the failure has occurred is detected;

a determination step of determining whether a first storage area of the blocked storage device is the prescribed area for each of the second areas based on the management information, which is stored in each of other multiple storage devices belonging to the same parity groups as the parity group to which the blocked storage device belongs; and

a restoration step of restoring, with respect to a second area determined to be the prescribed area, data stored in this second area, in accordance with a logical operation based on data stored in other multiple storage devices.

10. A storage control apparatus control method according to claim 9, wherein

the management information correspondingly manages for each of the second areas a first storage area of the storage device, with a first value denoting the number of data writes at production being associated with a second value denoting the current number of data writes, and

the determination step:

determines whether the first storage area of the blocked storage device is a data area or a parity area for each stripe set inside the parity group;

in a case where the first storage area is determined to be a data area, determines whether the data area is the prescribed area based on the management information related to the parity area and a prescribed determination criterion, and

in a case where the first storage area is determined to be parity area, determines whether the parity area is the prescribed area based on the management information related to the data areas and a prescribed determination criterion.

11. A storage control apparatus control method according to claim 10, wherein, based on the prescribed determination criterion, a determination is made that an area for which the first value and the second value do not match is the prescribed area.

12. A storage control apparatus control method according to claim 11, wherein

the management information further manages, in association with the second value, a third value for denoting whether or not data of the second area has been erased, and

based on the prescribed determination criterion, in a case where the third value does not denote a data erase, a determination is made that an area for which the first value and the second value do not match is the prescribed area.