STORAGE SYSTEM, STORAGE CONTROL APPARATUS, AND STORAGE CONTROL METHOD

• US 20130047029A1
• Filed: 08/08/2012
• Published: 02/21/2013
• Est. Priority Date: 08/17/2011
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: IKEUCHI, Kazuhiko, Daikokuya, Hidejirou, Maeda, Chikashi, Kubota, Norihide, Igashira, Atsushi, Kobayashi, Kenji, Tsukahara, Ryota
• Granted Patent: US 8,943,358 B2
• Time in Patent Office: Days
• US Class Current: 714/6.22
• CPC Class Codes: G06F 11/00 Error detection; Error correction; Monitoring error detection, correction or monitoring in information storage based on relative movement between record carrier and transducer G11B20/18; monitoring, i.e. supervising the progress of recording or reproducing G11B27/36; in static stores G11C29/00
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/14 Error detection or correction of the data by redundancy in operation G06F11/16 takes precedence
• CPC Class Codes: G06F 11/1415 at system level
• 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
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations
• CPC Class Codes: G06F 2211/1061 Parity-single bit-RAID4, i.e. RAID 4 implementations

Abstract

A storage control apparatus manages a plurality of storage devices which belong to an RLU such that data is made redundant between different storage devices. If a first storage device fails, a rebuild controller executes a rebuild process to store the same data as recorded in the first storage device in a spare storage device. When the rebuild controller executing the rebuild process has failed in reading out data from a second storage device, a data recovery controller restarts the first storage device, and reads out data to be stored in the spare storage device from the restarted first storage device.

Claims

1. A storage system comprising:

a plurality of storage devices;

a storage control apparatus configured to control recording of data in the plurality of storage devices such that data recorded in the plurality of storage devices is made redundant between different storage devices; and

a spare storage device configured to be used in place of any of the plurality of storage devices,

wherein the storage control apparatus;

executes, when a first storage device in the plurality of storage devices fails, a rebuild process to store the same data as data recorded in the first storage device in the spare storage device; and

reads out, when reading of data from a second storage device in the plurality of storage devices is unsuccessful in the rebuild process, data to be stored in the spare storage device from the first storage device.

2. The storage system according to claim 1, wherein the storage control apparatus further executes access processing to access data in the plurality of storage devices in response to an access request from a host apparatus, and

wherein, when the first storage device is in failure in the access processing, the storage control apparatus continues the access processing in response to the access request from the host apparatus, using remaining ones of the plurality of storage devices except the first storage device.

3. The storage system according to claim 2, wherein the storage control apparatus:

writes, upon receipt of a write request including data to be written into the first storage device, from the host apparatus during execution of the rebuild process, the data into the spare storage device,

performs, when reading of data from the second storage device is unsuccessful in the rebuild process, determination as to whether or not data has been written by the access processing into a location on the spare storage device, associated with the data whose reading is unsuccessful,

determines, when the data has been written, that the rebuild process with respect to the data has been completed, and

reads out, when the data has not been written, data to be stored in the spare storage device from the first storage device.

4. The storage system according to claim 3,

wherein the storage control apparatus:

reads out, when the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful, the data to be stored in the spare storage device from the first storage device, and

restarts, when reading of the data to be stored in the spare storage device from the first storage device is unsuccessful, the second storage device, and reads out the data whose reading is unsuccessful, from the restarted second storage device again.

5. The storage system according to claim 3,

wherein the storage control apparatus:

determines, when the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful, whether or not the data has been written by the access processing into a location on the second storage device, where the reading of the data is unsuccessful, during a time period after the first storage devices has failed and before the spare storage device becomes available for writing data by the access processing;

reads out, when the data has not been written, the data to be stored in the spare storage device from the first storage device; and

restarts, when the data has been written, the second storage device, and reads out the data whose reading is unsuccessful, from the restarted second storage device again.

6. The storage system according to claim 3, wherein:

all storage areas in the spare storage device are set to a state in which a readout error occurs, in advance; and

the storage control apparatus;

executes, when the reading of data from the second storage device is unsuccessful in the rebuild process, reading of data from the location on the spare storage device, associated with the data whose reading is unsuccessful,

determines, when the data has been normally read out, that the rebuild process with respect to the data has been completed, and

determines, when a data readout error occurs, that the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful.

7. The storage system according to claim 2,

wherein the storage control apparatus:

determines, when reading of data from the second storage device is unsuccessful in the rebuild process, whether or not data has been written by the access processing into a location on the second storage device, where the reading of the data is unsuccessful, during a time period after the first storage devices has failed and until now;

reads out, when the data has not been written, the data to be stored in the spare storage device from the first storage device; and

restarts, when the data has been written, the second storage device, and reads out the data whose reading is unsuccessful, from the restarted second storage device again.

8. The storage system according to claim 2, wherein after the first storage device has failed, when reading of data from the second storage device in response to a read request from the host apparatus has failed, the storage control apparatus reads out data from a location on the first storage device, associated with data requested to be read out.

9. A storage control apparatus that controls recording of data in a plurality of storage devices such that data recorded in the plurality of storage devices is made redundant between different storage devices, the storage control apparatus comprising one or more processors configured to perform a procedure including:

executing, when a first storage device in the plurality of storage devices fails, a rebuild process to store the same data as data recorded in the first storage device in the spare storage device; and

reading out, when reading of data from a second storage device in the plurality of storage devices is unsuccessful in the rebuild process, data to be stored in the spare storage device from the first storage device.

10. The storage control apparatus according to claim 9, wherein the procedure further includes access processing to access data in the plurality of storage devices in response to an access request from a host apparatus, and

wherein, when the first storage device is in failure in the access processing, the access processing in response to the access request from the host apparatus continues using remaining ones of the plurality of storage devices except the first storage device.

11. The storage control apparatus according to claim 10, wherein in the access processing, upon receipt of a write request including data to be written into the first storage device, from the host apparatus during execution of the rebuild process, the data is written into the spare storage device, and

wherein the procedure further includes:

performing, when reading of data from the second storage device is unsuccessful in the rebuild process, determination as to whether or not data has been written by the access processing into a location on the spare storage device, associated with the data whose reading is unsuccessful, and

reading out, when the data has not been written, data to be stored in the spare storage device, from the first storage device.

12. The storage control apparatus according to claim 11, wherein the procedure further includes:

reading out, when the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful, the data to be stored in the spare storage device from the first storage device, and

restarting, when reading of the data to be stored in the spare storage device from the first storage device is unsuccessful, the second storage device, and reading out the data whose reading is unsuccessful, from the restarted second storage device again.

13. A storage control method for a storage control apparatus that controls recording of data in a plurality of storage devices such that data recorded in the plurality of storage devices is made redundant between different storage devices, the storage control method comprising:

executing, when a first storage device in the plurality of storage devices fails, a rebuild process to store the same data as data recorded in the first storage device in the spare storage device; and

reading out, when reading of data from a second storage device in the plurality of storage devices is unsuccessful in the rebuild process, data to be stored in the spare storage device from the first storage device.

14. The storage control method according to claim 13, further comprising executing access processing to access accessing data in the plurality of storage devices in response to an access request from a host apparatus,

wherein, when the first storage device is in failure in the access processing, the access processing in response to the access request from the host apparatus continues using remaining ones of the plurality of storage devices except the first storage device.

15. The storage control method according to claim 14, wherein:

the access processing includes, upon receipt of a write request including data to be written into the first storage device, from the host apparatus during execution of the rebuild process, writing the data into the spare storage device; and

the storage control method further includes;

performing, when reading of data from the second storage device is unsuccessful in the rebuild process, determination as to whether or not data has been written by the access processing into a location on the spare storage device, associated with the data whose reading is unsuccessful,

determining, when the data has been written, that the rebuild process with respect to the data has been completed, and

reading out, when the data has not been written, data to be stored in the spare storage device from the first storage device.

16. The storage control method according to claim 15, further comprising:

reading out, when the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful, the data to be stored in the spare storage device from the first storage device, and

restarting, when reading of the data to be stored in the spare storage device from the first storage device is unsuccessful, the second storage device, and reading out the data whose reading is unsuccessful, from the restarted second storage device again.

17. The storage control method according to claim 15, further comprising:

determining, when the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful, whether or not the data has been written by the access processing into a location on the second storage device, where the reading of the data is unsuccessful, during a time period after the first storage devices has failed and before the spare storage device becomes available for writing data by the access processing;

reading out, when the data has not been written, the data to be stored in the spare storage device from the first storage device; and

restarting, when the data has been written, the second storage device, and reading outs the data whose reading is unsuccessful, from the restarted second storage device again.

18. The storage control method according to claim 15, wherein:

all storage areas in the spare storage device are set to a state in which a readout error occurs, in advance; and

the storage control method further includes;

executing, when the reading of data from the second storage device is unsuccessful in the rebuild process, reading of data from the location on the spare storage device, associated with the data whose reading is unsuccessful,

determining, when the data has been normally read out, that the rebuild process with respect to the data has been completed, and

determining, when a data readout error occurs, that the data has not been written by the access processing into the location on the spare storage device, associated with the data whose reading is unsuccessful.

19. The storage control method according to claim 14, further comprising:

determining, when reading of data from the second storage device is unsuccessful in the rebuild process, whether or not data has been written by the access processing into a location on the second storage device, where the reading of the data is unsuccessful, during a time period after the first storage devices has failed and until now;

reading out, when the data has not been written, the data to be stored in the spare storage device from the first storage device; and

restarting, when the data has been written, the second storage device, and reads out the data whose reading is unsuccessful, from the restarted second storage device again.

20. The storage control method according to claim 14, further comprising, after the first storage device has failed, when reading of data from the second storage device in response to a read request from the host apparatus has failed, reading out data from a location on the first storage device, associated with data requested to be read out.