Apparatus and method to access data in a raid array

• US 7,962,690 B2
• Filed: 01/04/2008
• Issued: 06/14/2011
• Est. Priority Date: 01/04/2008
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Klein, Craig Anthony, Haustein, Nils, Troppens, Ulf, Nielsen, Karl Allen, Winarski, Daniel James
• Primary Examiner(s): TSAI, SHENG JEN
• Application Number:
  US11/969,753
• Publication Number:
  US 20090177838A1
• Time in Patent Office: 1,257 Days
• Field of Search: 711/114, 711/E12.005
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 3/0617 in relation to availability
• 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

Abstract

A method to access a data in a RAID array comprising a plurality of data storage media, wherein information is written to said plurality of data storage media using a RAID configuration, wherein the method receives from a requester a command comprising a data access priority indicator. If a RAID rebuild is in progress, the method determines if the data access priority indicator is set. If the data access priority indicator is set, the method executes a command selected from the group consisting of writing information to the target logical block array range, and returning to the requestor information read from the target logical block array range.

Claims

1. A method to access a data in a RAID array, comprising the steps of:

supply a plurality of data storage media, wherein information is written to said plurality of data storage media using a RAID configuration;

receiving from a requestor a command selected from the group consisting of writing information to, and reading information from, one or more of said plurality of data storage media, wherein said command comprises a data access priority indicator;

establishing a target logical block array range;

determining if a RAID rebuild of said plurality of data storage media is in progress;

operative if a RAID rebuild of said plurality of data storage media is in progress, determining if each of one or more stripes comprising said target logical block array range have already been rebuilt;

operative if each of one or more stripes comprising said target logical block array range have already been rebuilt, determining if said data access priority indicator is set;

operative if said data access priority indicator is set, executing a command selected from the group consisting of writing information to said target logical block array range, and returning to said requestor information read from said target logical block array range

operative if said data priority indicator is not set, returning a busy signal.

2. The method of claim 1, wherein said data access priority indicator comprises a bit, wherein if said bit is set to “

1”

then said data access priority indicator is set, and wherein if said bit is set to “

0”

then said data access priority indicator is not set.

3. The method of claim 1, further comprising the step of executing said command if a RAID rebuild of said plurality of data storage media is not in progress.

4. The method of claim 1, further comprising the steps of:

operative if each of one or more stripes comprising said target logical block array range have not already been rebuilt, determining if said command comprises a write command;

operative if said command is a write command, rebuilding all stripes in said target logical block array range;

executing said write command.

5. The method of claim 4, further comprising the steps of:

updating parity;

updating a bitmap for all stripes as rebuilt.

6. The method of claim 5, further comprising the steps of continuing said RAID rebuild.

7. The method of claim 4, further comprising the steps of:

operative if said command is not a write command, determining if said data access priority indicator is set;

operative if said data access priority indicator is not set, returning a busy signal.

8. The method of claim 7, further comprising the steps of:

operative if said data access priority indicator is set;

rebuilding all stripes comprising said target logical block array range;

updating a bit map for all stripes as rebuilt; and

returning read data.

9. The method of claim 8, further comprising the step of continuing said RAID rebuild.

10. An article of manufacture comprising a processor and a computer readable medium having computer readable program code disposed therein to access data in a RAID array, wherein said RAID array comprises a plurality of data storage media, wherein information is written to said plurality of data storage media using a RAID configuration, the computer readable program code comprising a series of computer readable program steps to effect:

receiving from a requestor a command selected from the group consisting of writing information to, and reading information from, one or more of said plurality of data storage media, wherein said command comprises a data access priority indicator;

establishing a target logical block array range;

determining if a RAID rebuild of said plurality of data storage media is in progress;

operative if a RAID rebuild of said plurality of data storage media is in progress, determining if each of one or more stripes comprising said target logical block array range have already been rebuilt;

operative if each of one or more stripes comprising said target logical block array range have already been rebuilt, determining if said data access priority indicator is set;

operative if said data access priority indicator is set, executing a command selected from the group consisting of writing information to said target logical block array range, and returning to said requestor information read from said target logical block array range;

operative if said data priority indicator is not set, returning a busy signal.

11. The article of manufacture of claim 10, wherein said data access priority indicator comprises a bit, wherein if said bit is set to “

1”

then said data access priority indicator is set, and wherein if said bit is set to “

0”

then said data access priority indicator is not set.

12. The article of manufacture of claim 10, said computer readable program code further comprising a series of computer readable program steps to effect returning a busy signal if said data access priority indicator is not set.

13. The article of manufacture of claim 10, said computer readable program code further comprising a series of computer readable program steps to effect executing said command if a RAID rebuild of said plurality of data storage media is not in progress.

14. The article of manufacture of claim 10, said computer readable program code further comprising a series of computer readable program steps to effect:

operative if each of one or more stripes comprising said target logical block array range have not already been rebuilt, determining if said command comprises a write command;

operative if said command is a write command, rebuilding all stripes in said target logical block array range;

executing said write command.

15. The article of manufacture of claim 14, said computer readable program code further comprising a series of computer readable program steps to effect:

updating parity;

updating a bitmap for all stripes as rebuilt.

16. The article of manufacture of claim 15, said computer readable program code further comprising a series of computer readable program steps to effect continuing said RAID rebuild.

17. The article of manufacture of claim 14, said computer readable program code further comprising a series of computer readable program steps to effect:

operative if said command is not a write command, determining if said data access priority indicator is set;

operative if said data access priority indicator is not set, returning a busy signal.

18. The article of manufacture of claim 17, said computer readable program code further comprising a series of computer readable program steps to effect:

operative if said data access priority indicator is set;

rebuilding all stripes comprising said target logical block array range;

updating a bit map for all stripes as rebuilt; and

returning read data.

19. The article of manufacture of claim 18, said computer readable program code further comprising a series of computer readable program steps to effect continuing said RAID rebuild.