APPARATUS AND METHOD TO SELECT A DEDUPLICATION PROTOCOL FOR A DATA STORAGE LIBRARY

• US 20090235022A1
• Filed: 03/11/2008
• Published: 09/17/2009
• Est. Priority Date: 03/11/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: BATES, ALLEN KEITH, WINARSKI, DANIEL JAMES, KLEIN, CRAIG ANTHONY, HAUSTEIN, NILS, TROPPENS, ULF
• Granted Patent: US 8,234,444 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1084 Degraded mode, e.g. caused by single or multiple storage removals or disk failures

Abstract

A method to select a deduplication protocol for a data storage library comprising a plurality of data storage devices configured as a RAID array, by establishing a normal deduplication protocol, a RAID failure deduplication protocol, and a multiple storage device failure deduplication protocol. The method receives host data comprising a plurality of interleaved data blocks. If the system is operating without any storage device failures, then the method processes the host data using the normal deduplication protocol. If the system is operating with a storage device failure, then the method processes the host data using the RAID failure deduplication protocol. If the system is operating with multiple storage device failures, then the method processes the host data using the multiple storage device failure deduplication protocol.

Claims

1. A method to select a deduplication protocol for use in a data storage library comprising a plurality of data storage devices configured as a RAID array, comprising the steps of:

establishing a normal deduplication protocol;

establishing a RAID failure deduplication protocol;

establishing a multiple storage device failure deduplication protocol;

receiving host data comprising a plurality of interleaved data blocks;

determining if said RAID array is operating with a RAID failure;

operative if said RAID array is not operating with a RAID failure, processing said host data using said normal deduplication protocol.

2. The method of claim 1, wherein said normal deduplication protocol deduplicates between about 90 percent to about 100 percent of duplicative host data blocks.

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

operative if said RAID array is operating with a RAID failure, determining if said RAID array is operating with multiple storage device failures;

operative if said RAID array is operating with a RAID failure but not with multiple storage device failures, processing said host data using said RAID failure deduplication protocol.

4. The method of claim 3, wherein said RAID failure operation protocol deduplicates between about 40 percent to about 60 percent of duplicative host data blocks.

5. The method of claim 3, further comprising the step of processing said host data using said multiple storage device failure deduplication protocol if said RAID array is operating with multiple storage device failures.

6. The method of claim 5, wherein said multiple storage device failure operation protocol deduplicates between about 15 percent to about 35 percent of duplicative host data blocks.

7. A method to establish a data deduplication protocol for use in a data storage library comprising a plurality of data storage devices configured as a RAID array, comprising the steps of:

receiving a plurality of blocks of interleaved information;

determining a number (M) of failed data storage devices;

establishing a value for an offset factor (O);

calculating a value for (N), wherein (N)=(M+1)+(M)(O)

deduplicating every (N)th data block.

8. The method of claim 7, further comprising the step of setting (O) equal to 0 when (M) equals 0.

9. The method of claim 7, further comprising the step of setting (O) equal to 1 when (M) equals 1.

10. The method of claim 7, further comprising the step of setting (O) equal to 2 when (M) equals 2.

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

establishing a minimum RAID rebuild rate threshold;

establishing a maximum RAID rebuild threshold;

determining an actual RAID rebuild rate;

determining if said actual RAID rebuild rate is less than said minimum RAID rebuild rate threshold;

operative if said actual RAID rebuild rate is less than said minimum RAID rebuild rate threshold, setting (O) equal to 2.

12. The method of claim 11, further comprising the steps of:

operative if said actual RAID rebuild rate is not less than said minimum RAID rebuild rate threshold, determining if said actual RAID rebuild rate is less than said maximum RAID rebuild rate;

operative if said actual RAID rebuild rate is not less than said minimum RAID rebuild rate threshold and less than said maximum RAID rebuild rate, setting (O) equal to 1.

13. The method of claim 12, further comprising the step of setting (O) equal to 0 if said actual RAID rebuild rate is not less than said maximum RAID rebuild rate.

14. A RAID controller comprising a processor and a computer readable medium, a normal deduplication protocol encoded in said computer readable medium, a RAID failure deduplication protocol encoded in said computer readable medium, a multiple storage device failure deduplication protocol encoded in said computer readable medium, and computer readable program code encoded in said computer readable medium, said program readable code being useable with said processor to allocate deduplication resources in a data storage library comprising a plurality of data storage devices configured as a RAID array, the computer readable program code comprising a series of computer readable program steps to effect:

receiving host data comprising a plurality of interleaved data blocks;

determining if said RAID array is operating with a RAID failure;

operative if said RAID array is not operating with a RAID failure, processing said host data using said normal deduplication protocol.

15. The RAID controller of claim 14, wherein said computer readable program code to process said host data using said normal deduplication protocol further comprises a series of computer readable program steps to effect deduplicating between about 90 percent to about 100 percent of duplicative host data blocks.

16. The RAID controller of claim 14, said computer readable program code further comprising a series of computer readable program steps to effect:

operative if said RAID array is operating with a RAID failure, determining if said RAID array is operating with multiple storage device failures;

operative if said RAID array is operating with a RAID failure but not with multiple storage device failures, processing said host data using said RAID failure deduplication protocol.

17. The RAID controller of claim 16, wherein said computer readable program code to process said host data using said RAID failure deduplication protocol further comprises a series of computer readable program steps to effect deduplicating between about 40 percent to about 60 percent of duplicative host data blocks.

18. The RAID controller of claim 17, said computer readable program code further comprising a series of computer readable program steps to effect processing said host data using said multiple storage device failure deduplication protocol if said RAID array is operating with multiple storage device failures.

19. The RAID controller of claim 18, wherein said computer readable program code to process said host data using said RAID failure deduplication protocol further comprises a series of computer readable program steps to effect deduplicating between about 15 percent to about 35 percent of duplicative host data blocks.

20. A RAID controller comprising a processor, a computer readable medium, and computer readable program code encoded in said computer readable medium, said program readable code being useable with said processor to allocate deduplication resources in a data storage library comprising a plurality of data storage devices configured as a RAID array, the computer readable program code comprising a series of computer readable program steps to effect:

receiving a plurality of blocks of interleaved information;

determining a number (M) of failed data storage devices;

establishing a value for an offset factor (O);

determining a number (N) using a formula N=(M+1)+(M)(O)

deduplicating every (N)th data block.

21. The RAID controller of claim 20, said computer readable program code further comprising a series of computer readable program steps to effect setting (O) equal to 0 when (M) equals 0.

22. The RAID controller of claim 21, said computer readable program code further comprising a series of computer readable program steps to effect setting (O) equal to 1 when (M) equals 1.

23. The RAID controller of claim 20, further comprising said computer readable program code further comprising a minimum RAID rebuild rate threshold encoded in said computer readable medium and a maximum RAID rebuild threshold encoded in said computer readable medium, said computer readable program code further comprising a series of computer readable program steps to effect:

determining an actual RAID rebuild rate;

determining if said actual RAID rebuild rate is less than said minimum RAID rebuild rate threshold;

operative if said actual RAID rebuild rate is less than said minimum RAID rebuild rate threshold, setting (O) equal to 2.

24. The RAID controller of claim 23, said computer readable program code further comprising a series of computer readable program steps to effect:

operative if said actual RAID rebuild rate is not less than said minimum RAID rebuild rate threshold, determining if said actual RAID rebuild rate is less than said maximum RAID rebuild rate;

operative if said actual RAID rebuild rate is not less than said minimum RAID rebuild rate threshold and less than said maximum RAID rebuild rate, setting (O) equal to 1.

25. The RAID controller of claim 24, said computer readable program code further comprising a series of computer readable program steps to effect setting (O) equal to 0 if said actual RAID rebuild rate is not less than said maximum RAID rebuild rate.