Storage system, storage control device, and storage control method

• US 20070002482A1
• Filed: 09/29/2005
• Published: 01/04/2007
• Est. Priority Date: 06/30/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Sato, Hiroaki, Konta, Yoshihito, Yoshiya, Yukihiro, Daikokuya, Hidejirou, Kubota, Norihide, Hirano, Tadashi, Ito, Mikio, Takahashi, Hideo, Ikeuchi, Kazuhiko, Nakagami, Tsuyoshi, Kikuchi, Nobuyuki, Toshine, Naoyoshi, Inai, Yusuke, Takahashi, Eisaku, Sato, Yasutake, Shimmitsu, Masaru, Ikeno, Masami, Noda, Yuuji
• Granted Patent: US 7,590,884 B2
• Time in Patent Office: Days
• US Class Current: 360/53
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1612 where the redundant component is persistent storage
• CPC Class Codes: G06F 11/2056 by mirroring
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0623 in relation to content
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11B 20/1879 Direct read-after-write methods
• CPC Class Codes: G11B 2020/183 wherein at least one additional attempt is made to read or write the data when a first attempt is unsuccessful

Abstract

In a storage system, a disk device performs recovery and transfers read data to a control device, and the control device judges the validity of the recovery to prevent a transfer of erroneous data. A control device read-accesses a disk device, and the disk device returns read data and a recovered read error response. A control device, at the time of an initial recovered read error, performs a retry of a similar command, and if an error does not occur for read commands including the retry read command, judges the data to be valid. Uncertain data (suspect data) upon occurrence of a recovered read error is restored through disk retry, and accurate read data can be transferred to the host.

Claims

1. A storage system, comprising:

at least one disk device; and

a control unit which performs reading and writing of data from and to said disk device according to requests from a higher-level apparatus,

wherein said control unit comprises;

a cache memory which stores data of said disk device; and

a processing unit which read-accesses said disk device and receives read data and a response result from said disk device,

and wherein said processing unit, when said response upon receiving said read data is a recovered read error response, performs retry read access of the same data on said disk device, discriminates whether the response from said disk device accessed by said retry read does not include an error, and judges the read data obtained from said retry read access to be valid.

2. The storage system according to claim 1, wherein said processing unit, after executing said retry read access, performs read access of said disk device with usage of the cache memory of said disk device disabled, receives the read data, compares the read data with the read data obtained at the time of said recovered read error response, and executes diagnostics of said disk device.

3. The storage system according to claim 1,

wherein said disk device comprises a plurality of disk devices configured as a redundant system,

and said processing unit, in response to the fact that the response to read access of one of said disk devices is said recovered read error response, performs retry read access of the same data on another of said disk devices constituting said redundant system.

4. The storage system according to claim 3,

wherein said processing unit discriminates that read data obtained by retry read access of the other of said disk devices constituting said redundant system does not comprise an error response, judges the read data obtained by said retry read access to be valid, and transfers said read data to an external apparatus.

5. The storage system according to claim 1,

wherein said processing unit, after executing said retry read access, performs read access of said one disk device with usage of the cache memory of said disk device disabled, receives read data, compares the read data with read data from said other disk device, and executes diagnostics of said one disk device.

6. The storage system according to claim 5,

wherein, when said comparison result is satisfactory, said processing unit executes replacement processing of the relevant area of said one disk device.

7. The storage system according to claim 5,

wherein, when said comparison result is not satisfactory, said processing unit executes detachment processing of said one disk device.

8. The storage system according to claim 1,

wherein said processing unit, in response to said recovered read error response, performs retry read access of the same data on said read-accessed disk device with usage of cache memory disabled, discriminates that the response from said disk device to said retry read access does not comprise an error, and judges the read data obtained by said retry read access to be valid.

9. The storage system according to claim 8,

wherein said processing unit, in response to reception of a repeated recovered read error response from said retry read-accessed disk device, again performs retry read access of the same data on said read-accessed disk device with usage of cache memory disabled, discriminates that an error is not included, compares the read data with the read data obtained at the time of said recovered read error response, and executes diagnostics of said disk device.

10. The storage system according to claim 9,

wherein, when said comparison result is satisfactory, said processing unit executes replacement processing of the relevant area of said disk device, and transfers said read data to an external apparatus.

11. The storage system according to claim 9,

wherein, when said comparison result is not satisfactory, said processing unit executes replacement processing of the relevant area of said disk device, and notifies said external apparatus of an error.

12. A storage control device, which in response to a request from a higher-level apparatus performs reading and writing of data from and to at least one disk device, comprising:

a cache memory which stores data of said disk device; and

a processing unit which read-accesses said disk device, and receives read data and a response result from said disk device,

wherein said processing unit, when said response upon receiving said read data is a recovered read error response, performs retry read access of the same data on said disk device, discriminates that the response from said disk device to said retry read access does not comprise an error, and judges the read data obtained by said retry read access to be valid.

13. The storage control device according to claim 12, wherein said processing unit, after executing said retry read access, performs read access of said disk device with usage of the cache memory of said disk device disabled, receives the read data, compares the read data with the read data obtained at the time of said recovered read error response, and executes diagnostics of said disk device.

14. The storage control device according to claim 12,

wherein said disk device comprises a plurality of disk devices configured as a redundant system,

and said processing unit, in response to the fact that the response to read access of one of said disk devices is said recovered read error response, performs retry read access of the same data on another of said disk devices constituting said redundant system.

15. The storage control device according to claim 14, wherein said processing unit discriminates that read data obtained by retry read access of the other of said disk devices constituting said redundant system does not comprise an error response, judges the read data obtained by said retry read access to be valid, and transfers said read data to an external apparatus.

16. The storage control device according to claim 12, wherein said processing unit, after executing said retry read access, performs read access of said one disk device with usage of the cache memory of said disk device disabled, receives read data, compares the read data with read data from said other disk device, and executes diagnostics of said one disk device.

17. The storage control device according to claim 16, wherein, when said comparison result is satisfactory, said processing unit executes replacement processing of the relevant area of said one disk device.

18. The storage control device according to claim 16, wherein, when said comparison result is not satisfactory, said processing unit executes detachment processing of said one disk device.

19. The storage control device according to claim 12, wherein, in response to said recovered read error response, said processing unit performs retry read access of the same data on said read-accessed disk device with usage of cache memory disabled, discriminates that the response from said disk device to said retry read access does not comprise an error, and judges the read data obtained by said retry read access to be valid.

20. The storage control device according to claim 19, wherein, in response to reception of a repeated recovered read error response from said retry read-accessed disk device, said processing unit again performs retry read access of the same data on said read-accessed disk device with usage of cache memory disabled, discriminates that an error is not included, compares the read data with the read data obtained at the time of said recovered read error, and executes diagnostics of said disk device.

21. The storage control device according to claim 20, wherein, when said comparison result is satisfactory, said processing unit executes replacement processing of the relevant area of said disk device, and transfers said read data to an external apparatus.

22. The storage control device according to claim 20, wherein, when said comparison result is not satisfactory, said processing unit executes replacement processing of the relevant area of said disk device, and notifies said external apparatus of an error.

23. A storage control method for performing reading and writing of data from and to at least one disk device, in response to a request from a higher-level apparatus, comprising the steps of:

read-accessing said disk device, and receiving read data and a response result from said disk device;

performing retry read access of the same data on said disk device when said response upon reception of said read data is a recovered read error response; and

discriminating that the response from said disk device to said retry read access does not comprise an error, and judging the read data obtained by said retry read access to be valid.

24. The storage control method according to claim 23, further comprising:

a step of performing, after execution of said retry read access, read access of said disk device with usage of the cache memory of said disk device disabled; and

a step of comparing the read data with the read data obtained at the time of said recovered read error response, and of executing diagnostics of said disk device.

25. The storage control method according to claim 24, wherein said retry read access step comprises a step, in response to the fact that the response to read access of said one disk device constituted by a plurality of disk devices of a redundant system is said recovered read error response, of performing retry read access of the same data on said other disk device constituting said redundant system.

26. The storage control method according to claim 25, wherein said validity judgment step comprises:

a step of discriminating that the read data, obtained upon retry read access of said other disk device constituting said redundant system, does not comprise an error response;

a step of judging the read data obtained by said retry read access to be valid; and

a step of transferring said read data to an external apparatus.

27. The storage control method according to claim 23, further comprising:

a step, after execution of said retry read access, of performing read access of said one disk device with usage of cache memory of said disk device disabled;

a step of receiving the read data; and

a step of comparing the read data with the read data from said other disk device and of executing diagnostics of said one disk device.

28. The storage control method according to claim 27, further comprising a step, when said comparison result is satisfactory, of executing replacement processing of the relevant area of said one disk device.

29. The storage control method according to claim 27, further comprising a step, when said comparison result is not satisfactory, of executing detachment processing of said one disk device.

30. The storage control method according to claim 23, wherein said retry read access step comprises a step, in response to said recovered read error response, of performing retry read access of the same data on said read-accessed disk device with usage of cache memory disable,

and said validity judgment step comprises:

a step of discriminating that the response from said disk device to said retry read access does not comprise an error; and

a step of judging the read data obtained by said retry read access to be valid.

31. The storage control method according to claim 30, further comprising:

a step of again performing, in response to the reception of a repeated recovered read error response from said disk device of said retry read access, retry read access of the same data on said read-accessed disk device with usage of cache memory disabled;

a step of discriminating that an error is not included, and of comparing the read data with the read data obtained at the time of said recovered read error, and of executing diagnostics of said disk device.

32. The storage control method according to claim 31, further comprising:

a step, when said comparison result is satisfactory, of executing replacement processing of the relevant area of said disk device; and

a step of transferring said read data to an external apparatus.

33. The storage control method according to claim 31, further comprising:

a step, when said comparison result is not satisfactory, of executing replacement processing of the relevant area of said disk device; and

a step of notifying said external apparatus of an error.