Storage system, control method, and program

• US 20070180294A1
• Filed: 05/31/2006
• Published: 08/02/2007
• Est. Priority Date: 02/02/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Sato, Yuichi, Sazawa, Shinichi, Kameyama, Hiroaki
• Granted Patent: US 7,739,579 B2
• Time in Patent Office: Days
• US Class Current: 714/6
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems

Abstract

A storage apparatus composed of a plurality of magnetic disk devices are provided. An encoding unit generates, after dividing original data, a plurality pieces of encoded data equal to or more than the number of division by use of a code of which redundancy is variable. A redundancy control unit varies the redundancy in the encoding unit in accordance with the importance of the original data. A distribution processing unit distributes and stores the plurality of encoded data to and in the plurality of magnetic disk devices. A decoding unit retrieves the encoded data corresponding to, at least, the division number of the original data from the magnetic disk devices so as to decode the original data.

Claims

1. A storage system having a storage apparatus composed of a plurality of storage devices, characterized by having

an encoding unit for, after dividing original data, generating a plurality of encoded data equal to or more than the division number by use of a code of which redundancy is variable;

a redundancy control unit for varying the redundancy in the encoding unit;

a distribution processing unit for distributing the plurality of encoded data to the plurality of storage devices and causing the encoded data to be stored in the storage devices; and

a decoding unit for retrieving the encoded data corresponding to at least the division number of the original data from the storage devices and decoding the original data.

2. The system according to claim 1 characterized in that

the encoding unit has a block dividing unit for dividing the original data into n-units of block data, and

an encoded data generating unit for generating, merely by a number m according to redundancy Q, headers, in each of which a bitmap specifying one or a plurality of blocks for obtaining exclusive OR in the n-units of block data is disposed, and encoded data comprised of exclusive OR data of the one or plurality of block data specified by the header part;

wherein

the decoding unit retrieves the block number n or more of the encoded data from the plurality of storage devices, and converts the header part into a unit matrix so as to decode the n-units of block data.

3. The system according to claim 1, characterized in that the redundancy control unit varies the redundancy in the encoding unit in accordance with importance of the original data.

4. The system according to claim 3, characterized in that, in the redundancy control unit, the importance of the original data is manually set or automatically set in accordance with a keyword contained in the original data, update date and time, or update frequency.

5. The system according to claim 4, characterized in that, as the automatic setting of the importance, the redundancy control unit sets importance corresponding to the keyword contained in the original data, and then, corrects the importance in accordance with the update date and time and/or the update frequency.

6. The system according to claim 1, characterized in that the distribution processing unit determines the distribution number of the plurality of encoded data in accordance with reliability or usable capacity of the plurality of storage devices.

7. The system according to claim 6, characterized in that, in the distribution processing unit, the reliability of the storage device is manually set or automatically set based on operating time.

8. The system according to claim 6, characterized in that the distribution processing unit sets the importance of the storage device in accordance with the operating time, and then, corrects the importance in accordance with a usable capacity of the storage device.

9. The system according to claim 1, characterized in that, when the storage device is newly added or eliminated, based on the storage devices after the change, the encoded data is regenerated in the encoding unit, and then, the encoded data is redistributed by the distribution processing unit.

10. A control method of a storage system having a storage apparatus composed of a plurality of storage devices, characterized by having

an encoding step of, after dividing original data, generating a plurality of encoded data equal to or more than the division number by use of a code of which redundancy is variable;

a redundancy control step of varying the redundancy in the encoding step;

a distribution processing step of distributing the plurality of encoded data to the plurality of storage devices and causing the encoded data to be stored in the storage devices; and

a decoding step of retrieving the encoded data corresponding to at least the division number of the original data from the storage devices and decoding the original data.

11. The control method of the storage system described in claim 10 characterized in that

the encoding step has a block dividing step of dividing the original data into n-units of block data, and

an encoded data generating step of generating, merely by a number m according to redundancy Q, headers, in each of which a bitmap specifying one or a plurality of blocks for obtaining exclusive OR in the n-units of block data is disposed, and encoded data comprised of exclusive OR data of the one or plurality of block data specified by the header step;

wherein

in the decoding step, the block number n or more of the encoded data is retrieved from the plurality of storage devices, and the header step is converted into a unit matrix so as to decode the n-units of block data.

12. The method according to claim 10, characterized in that, in the redundancy control step, the redundancy in the encoding step is varied in accordance with importance of the original data.

13. The method according to claim 12, characterized in that, in the redundancy control step, the importance of the original data is manually set or automatically set in accordance with a keyword contained in the original data, update date and time, or update frequency.

14. The method according to claim 13, characterized in that, in the redundancy control step, as the automatic setting of the importance, importance corresponding to the keyword contained in the original data is set, and then, the importance is corrected in accordance with the update date and time and/or the update frequency.

15. The method according to claim 11, characterized in that, in the distribution processing step, the distribution number of the plurality of encoded data is determined in accordance with reliability and/or usable capacity of the plurality of storage devices.

16. The method according to claim 15, characterized in that, in the distribution processing step, the reliability of the storage device is manually set or automatically set based on operating time.

17. The method according to claim 15, characterized in that, in the distribution processing step, the importance of the storage device is set in accordance with the operating time, and then, corrected in accordance with a usable capacity of the storage device.

18. The method according to claim 10, characterized in that, when the storage device is newly added or eliminated, based on the storage devices after the change, the encoded data is regenerated in the encoding step, and then, redistributed in the distribution processing step.

19. A computer-readable storage medium which stores a storage control program characterized by causing a computer of a storage system having a main storage apparatus for storing original data and a plurality of storage devices for distributing and storing the data of the storage apparatus, to execute

an encoding step of, after dividing original data, generating a plurality of encoded data equal to or more than the division number by use of a code of which redundancy is variable;

a redundancy control step of varying the redundancy in the encoding step;

a distribution processing step of distributing the plurality of encoded data to the plurality of storage devices and causing the encoded data to be stored in the storage devices; and

a decoding step of retrieving the encoded data corresponding to at least the division number of the original data from the storage devices and decoding the original data.

20. The storage medium according to claim 19 characterized in that

the encoding step has a block dividing step of dividing the original data into n-units of block data, and

an encoded data generating step of generating, merely by a number m according to redundancy Q. headers, in each of which a bitmap specifying one or a plurality of blocks for obtaining exclusive OR in the n-units of block data is disposed, and encoded data comprised of exclusive OR data of the one or plurality of block data specified by the header step;

wherein

in the decoding step, the block number n or more of the encoded data is retrieved from the plurality of storage devices, and the header step is converted into a unit matrix by means of the Gaussian elimination method so as to decode the n-units of block data.