METHOD OF, AND APPARATUS FOR, IMPROVED DATA INTEGRITY

• US 20130198585A1
• Filed: 02/01/2012
• Published: 08/01/2013
• Est. Priority Date: 02/01/2012
• Status: Abandoned Application

• Current Assignee: Xyratex Technology Limited (Seagate Technology Holdings Plc)
• Original Assignee: Xyratex Technology Limited (Seagate Technology Holdings Plc)
• Inventors: BRAAM, Peter J., RUTMAN, Nathaniel
• Application Number:
  US13/364,150
• Publication Number:
  US 20130198585A1
• Time in Patent Office: Days
• US Class Current: 714/763
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations

Abstract

There is provided a method of writing data to a data sector of a storage device. The data sector has at least one parity sector associated therewith, each sector being configured to include a data field and a data integrity field. The data integrity field including a guard field, an application field and a reference field. The method includes providing data to be written to an intended sector; generating, for the intended sector, version information for the sector; generating a version vector based on the version information for the data sector; and writing the data to the data field of the data sector; writing the version information to the application field of the data sector; and writing the version vector to the application field of the parity sector.

Claims

1. A method of writing data to a data sector of a storage device, the data sector having at least one parity sector associated therewith, each sector being configured to comprise a data field and a data integrity field, the data integrity field comprising a guard field, an application field and a reference field, the method comprising:

providing data to be written to an intended sector;

generating, for said intended sector, version information for said sector;

generating a version vector based on said version information for said data sector; and

writing said data to the data field of the data sector;

writing said version information to the application field of the data sector;

writing said version vector to the application field of the parity sector.

2. A method according to claim 1, further comprising:

writing said data in units of blocks, wherein each block comprises a plurality of sectors.

3. A method according to claim 2, wherein each sector within a given block is allocated the same version number.

4. A method according to claim 1, wherein the version number of a sector is changed each time said sector is written to.

5. A method according to claim 4, wherein the version number is incremented each time the sector is written to.

6. A method according to claim 4, wherein the version number is changed randomly each time the sector is written to.

7. A method according to claim 6, wherein the version number is changed randomly for all blocks.

8. A method according to claim 6, wherein the version number is changed randomly independently for each block or group of blocks.

9. A method according to claim 4, wherein the version number is incremented and randomly selected.

10. A method according to claim 2, further comprising:

writing said data in units of stripe units, each stripe unit comprising a plurality of blocks.

11. A method according to claim 10, wherein said intended sector comprises part of a stripe unit and the method comprises, after said step of providing:

reading version information from stripe units associated with said stripe unit;

reading the version vector associated with said stripe units;

determining whether a mismatch has occurred between the version information and the version vector and, if a mismatch has occurred, correcting said data.

12. A method according to claim 1, wherein said version vector comprises the version information for each data sector.

13. A method according to claim 12, wherein said version vector comprises a reduction function of said version information.

14. A method according to claim 1, wherein the or each data sector is in accordance with the T10 format.

24. A computer program product executable by a programmable processing apparatus, comprising one or more software portions for performing the steps of any one of claim 1.

26. A computer usable storage medium having a computer program product according to claim 24 stored thereon.

15. A method of reading data from a sector of a storage device, the data sector having at least one parity sector associated therewith, each sector being configured to comprise a data field and a data integrity field, the data integrity field comprising a guard field, an application field and a reference field, the method comprising:

executing a read request for reading of data from a data sector;

reading version information from the application field of said data sector;

reading version vector from the application field of a parity sector associated with said data sector;

determining whether a mismatch has occurred between the version information and the version vector and, if a mismatch has occurred, correcting said data; and

reading the data from said data sector.

16. A method according to claim 15, wherein the or each data sector is in accordance with the T10 format.

25. A computer program product executable by a programmable processing apparatus, comprising one or more software portions for performing the steps of claim 15

27. A computer usable storage medium having a computer program product according to claim 25 stored thereon.

17. A controller operable to write data to a data sector of a storage device, the data sector having at least one parity sector associated therewith, each sector being configured to comprise a data field and a data integrity field, the data integrity field comprising a guard field, an application field and a reference field, the controller being operable to provide data to be written to an intended sector, generate, for said intended sector, version information for said sector, to write said data to the data field of the data sector, to write said version information to the application field of the data sector, to generate a version vector based on said version information for said data sector;

and to write said version vector to the application field of the parity sector.

19. Data storage apparatus comprising at least one storage device and the controller of claim 17.

22. A storage protocol according to claim 19, wherein said data sectors are associated with at least one parity sector, the application field of said parity sector being configured to store a version vector representing the version information for the or each data sector associated with said parity sector.

23. A storage protocol according to claim 19 in the form of a T10 storage protocol.

18. A controller operable to read data from a sector of a storage device, the data sector having at least one parity sector associated therewith, each sector being configured to comprise a data field and a data integrity field, the data integrity field comprising a guard field, an application field and a reference field, the controller being operable to execute a read request for reading of data from a data sector, to read version information from the application field of said data sector, to read a version vector from the application field of a parity sector associated with said data sector, to determine whether a mismatch has occurred between the version information and the version vector and, if a mismatch has occurred, to correct said data and to read the data from said data sector.

20. Data storage apparatus comprising at least one storage device and the controller of claim 18.

21. A storage protocol for storage of data, the storage protocol comprising a data sector format comprising a data field and a data integrity field, the data integrity field comprising a guard field, an application field and a reference field, wherein data sectors in accordance with said storage protocol are configured to store version information in said application field, said version information being modified when said sector is modified.