Storage control device and data recovery method for storage control device

• US 20070220313A1
• Filed: 04/14/2006
• Published: 09/20/2007
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Fukuoka, Mikio, Katsuragi, Eiju
• Granted Patent: US 7,451,346 B2
• Time in Patent Office: Days
• US Class Current: 714/6
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence

Abstract

The present invention efficiently recovers an error drive by suppressing futile copying. When the number of errors of the disk drive is equal to or more than a first threshold, data stored in the disk drive is copied to a spare drive by a drive copy section. When the number of errors of the disk drive is equal to or more than a second threshold prior to completion of the drive copy, the disk drive is closed, and a correction copy by a correction copy section is started in place of the drive copy. The correction copy section starts the correction copy from the position where the drive copy is interrupted by taking over the drive copy completion position (copy interrupt position) managed by a copy progress condition management section.

Claims

1. A storage control device comprising a plurality of storage devices including at least one spare storage device, comprising:

an error condition detection section that detects the error condition of each of the storage devices;

an input/output request control section that, when an error is detected by the error condition detection section, controls the input/output request from a host computer with respect to the storage device in which the error has been detected; and

a recovery control section that, when the error condition detected by the error condition detection section exceeds a preset threshold, recovers the stored content of a recovery-target storage device, in which the error has been detected, in the spare storage device,

wherein the recovery control section comprises;

a first copy mode that reads data from the recovery-target storage device and copies the data thus read to the spare storage device; and

a second copy mode that restores data stored in the recovery-target storage device on the basis of data read from other storage devices belonging to the same RAID group as the recovery-target storage device and copies the restored data to the spare storage device, and wherein

when shifting from the first copy mode to the second copy mode, the recovery control section starts the second copy mode from the copy interrupt position of the first copy mode.

2. The storage control device according to claim 1, wherein the recovery control section recovers the stored content of the recovery-target storage device by executing the first copy mode when the error condition detected by the error condition detection section is equal to or more than a first threshold and less than a second threshold, and

recovers the stored content of the recovery-target storage device continuously by shifting from the first copy mode to the second copy mode when the error condition detected by the error condition detection section is equal to or more than the second threshold.

3. The storage control device according to claim 1, wherein, when shifting from the first copy mode to the second copy mode, the recovery control section secures the spare storage device used by the first copy mode and starts the second copy mode by using the secured spare storage device.

4. The storage control device according to claim 1, wherein the recovery control section executes the first copy mode and the second copy mode serially as one process.

5. The storage control device according to claim 1, wherein, when the error condition detected by the error condition detection section is equal to or more than a first threshold and less than a second threshold, a first status for selecting the first copy mode is set for the recovery-target storage device, and, when the error condition detected by the error condition detection section is equal to or more than the second threshold, a second status for selecting the second copy mode is set for the recovery-target storage device, and

the recovery control section:

copies data in predetermined amounts at a time from the recovery-target storage device to the spare storage device by starting the first copy mode when the first status has been set for the recovery-target storage device;

updates copy position management information for managing the copy completion position each time a data copy of the predetermined amount is completed;

confirms the status of the recovery-target storage device each time the copy position management information is updated; and

shifts from the first copy mode to the second copy mode by using the copy position management information continuously when the status of the recovery-target storage device is changed from the first status to the second status.

6. The storage control device according to claim 1, wherein the input/output request control section stores and manages, as update management information, the condition of the update to the spare storage device by the host computer;

and

the recovery control section executes the first copy mode or the second copy mode with respect to a storage area other than the updated storage area.

7. The storage control device according to claim 6, wherein the input/output request control section specifies a storage device that is used to process input/output requests from the host computer on the basis of the update management information.

8. The storage control device according to claim 1, wherein, when a plurality of the second copy mode are started within the same RAID group, the recovery control section stores data that has been recovered by means of a second copy mode whose processing precedes other processing to a spare storage device of the preceding second copy mode and a spare storage device of a second copy mode whose processing is delayed respectively.

9. A method for recovering data stored in a storage control device comprising a RAID group constituted by a plurality of storage devices, the method comprising the steps of:

detecting an error condition relating to each storage device in the RAID group;

setting a first status for selecting a first copy mode for a recovery-target storage device in which an error has been detected when the detected error condition is equal to or more than a first threshold and less than a second threshold;

setting a second status for selecting a second copy mode for the recovery-target storage device when the detected error condition is equal to or more than the second threshold;

copying data in predetermined amounts at a time from the recovery-target storage device to the spare storage device by starting the first copy mode when the first status is set for the recovery-target storage device;

updating copy position management information for managing a copy completion position each time a data copy of the predetermined amount is completed;

confirming the status of the recovery-target storage device each time the copy position management information is updated;

shifting from the first copy mode to the second copy mode by using the copy position management information continuously when the status of the recovery-target storage device is changed from the first status to the second status, and restoring data that has been stored in the recovery-target storage device on the basis of data that is read from the other storage devices belonging to the same RAID group as the recovery-target storage device; and

copying the restored data to the spare storage device.