ERROR CHECKING ADDRESSABLE BLOCKS IN STORAGE

• US 20080256420A1
• Filed: 04/12/2007
• Published: 10/16/2008
• Est. Priority Date: 04/12/2007
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Kubo, Robert Akira, Hafner, James Lee, O'Connor, James A., Kahler, David Ray, Nielsen, Karl Allen, Surugucchi, Krishnakumar Rao, Mannenbach, David Frank, Stelmach, Richard B.
• Granted Patent: US 8,370,715 B2
• Time in Patent Office: Days
• US Class Current: 714/770
• CPC Class Codes: G06F 11/1004 to protect a block of data words, e.g. CRC or checksum G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems

Abstract

Provided are a method, system, and article of manufacture for error checking addressable blocks in storage. Addressable blocks of data are stored in a storage in stripes, wherein each stripe includes a plurality of data blocks for one of the addressable blocks and at least one checksum block including checksum data derived from the data blocks for the addressable block. A write request is received to modify data in one of the addressable blocks. The write and updating the checksum are performed in the stripe having the modified addressable block. An indication is made to perform an error checking operation on the stripe for the modified addressable block in response to the write request, wherein the error checking operation reads the data blocks and the checksum in the stripe to determine if the checksum data is accurate. An error handling operation is initiated in response to determining that the checksum data is not accurate.

Claims

1. An article of manufacture having code enabled to cause operations with respect to a storage and a memory and to cause operations comprising:

storing addressable blocks of data in the storage in stripes, wherein each stripe includes a plurality of data blocks for one of the addressable blocks and at least one checksum block including checksum data derived from the data blocks for the addressable block;

receiving a write request to modify data in one of the addressable blocks;

performing the write and updating the checksum in the stripe having the modified addressable block;

indicating in the memory to perform an error checking operation on the stripe for the modified addressable block in response to the write request, wherein the error checking operation reads the data blocks and the checksum in the stripe to determine if the checksum data is accurate; and

initiating an error handling operation in response to determining that the checksum data is not accurate.

2. The article of manufacture of claim 1, wherein indicating to perform the error checking comprises indicating the modified addressable block in a modified list, wherein the error checking operation processes the modified list to check the checksum data for addressable blocks in the modified list.

3. The article of manufacture of claim 2, wherein the modified list comprises a most recently modified list and wherein the error checking operation processes the stripe for a most recently modified addressable block indicated in the modified list.

4. The article of manufacture of claim 3, wherein the operations further comprise:

recalculating the checksum in the stripe as part of the error checking operation or a write during which the at least one checksum block is recalculated using all the data blocks in the stripe; and

removing the stripe from the recently modified list in response to recalculating the at least one checksum using all the data blocks in the stripe.

5. The article of manufacture of claim 2, wherein the operations further comprise:

initiating a background operation to read the data blocks and the at least one checksum in each stripe for a plurality of addressable blocks to determine if the at least one checksum data is accurate, wherein the plurality of addressable blocks on which to perform the background operation includes modified and unmodified data.

6. The article of manufacture of claim 5, wherein the operations further comprise:

alternating between processing m stripes as part of the background operation and n stripes as part of the error checking operation processing modified addressable blocks indicated in the modified list, wherein m is greater than n.

7. The article of manufacture of claim 1, wherein the data and checksum blocks in one stripe are written to different storage devices according to a Redundant Array of Independent Disk (RAID) algorithm.

8. An article of manufacture having code enabled to cause operations with respect to a storage and a memory and to cause operations comprising:

storing addressable blocks of data in the storage in stripes, wherein each stripe includes a plurality of data blocks for one of the addressable blocks and least one checksum block including checksum data derived from the data blocks for the addressable block;

receiving a write request to update one of the addressable blocks;

initiating a first error checking operation to read the data blocks and checksum in the stripe for each addressable block in the storage having user data to determine if the checksum data is accurate;

maintaining a list of modified addressable block in the memory;

initiating a second error checking operation to read the data blocks and checksum in the stripe for at least one of the addressable blocks indicated in the list to determine whether the checksum data is accurate; and

initiating an error handling operation in response to determining that the checksum data does not accurately reflect the data blocks in response to at least one of the first and second error checking operations.

9. The article of manufacture of claim 8, wherein the list comprises a most recently modified list and wherein the second error checking operation processes the stripe for a most recently modified addressable block indicated in the list, and wherein the operations further comprise:

alternating between processing m stripes as part of the first error checking operation and n stripes as part of the second error checking operation, wherein m is greater than n.

10. A system in communication with a storage, comprising:

a memory;

storage manager code enabled to cause operations, the operations comprising;

storing addressable blocks of data in the storage in stripes, wherein each stripe includes a plurality of data blocks for one of the addressable blocks and at least one checksum block including checksum data derived from the data blocks for the addressable block;

receiving a write request to modify data in one of the addressable blocks;

performing the write and updating the checksum in the stripe having the modified addressable block;

indicating in the memory to perform an error checking operation on the stripe for the modified addressable block in response to the write request, wherein the error checking operation reads the data blocks and the checksum in the stripe to determine if the checksum data is accurate; and

initiating an error handling operation in response to determining that the checksum data is not accurate.

11. The system of claim 10, wherein indicating to perform the error checking comprises indicating the modified addressable block in a modified list in the memory, wherein the error checking operation processes the modified list to check the checksum data for addressable blocks in the modified list.

12. The system of claim 11, wherein the modified list comprises a most recently modified list and wherein the error checking operation processes the stripe for a most recently modified addressable block indicated in the modified list.

13. The system of claim 12, wherein the operations further comprise:

recalculating the checksum in the stripe as part of the error checking operation or a write during which the at least one checksum block is recalculated using all the data blocks in the stripe; and

removing the stripe from the recently modified list in response to recalculating the at least one checksum using all the data blocks in the stripe.

14. The system of claim 11, wherein the operations further comprise:

initiating a background operation to read the data blocks and the at least one checksum in each stripe for a plurality of addressable blocks to determine if the at least one checksum data is accurate, wherein the plurality of addressable blocks on which to perform the background operation includes modified and unmodified data.

15. The system of claim 14, wherein the operations further comprise:

alternating between processing m stripes as part of the background operation and n stripes as part of the error checking operation processing modified addressable blocks indicated in the modified list, wherein m is greater than n.

16. A method, comprising:

storing addressable blocks of data in a storage in stripes, wherein each stripe includes a plurality of data blocks for one of the addressable blocks and at least one checksum block including checksum data derived from the data blocks for the addressable block;

receiving a write request to modify data in one of the addressable blocks;

performing the write and updating the checksum in the stripe having the modified addressable block;

indicating to perform an error checking operation on the stripe for the modified addressable block in response to the write request, wherein the error checking operation reads the data blocks and the checksum in the stripe to determine if the checksum data is accurate; and

initiating an error handling operation in response to determining that the checksum data is not accurate.

17. The method of claim 16, wherein indicating to perform the error checking comprises indicating the modified addressable block in a modified list, wherein the error checking operation processes the modified list to check the checksum data for addressable blocks in the modified list.

18. The method of claim 17, wherein the modified list comprises a most recently modified list and wherein the error checking operation processes the stripe for a most recently modified addressable block indicated in the modified list.

19. The method of claim 18, further comprising:

recalculating the checksum in the stripe as part of the error checking operation or a write during which the at least one checksum block is recalculated using all the data blocks in the stripe; and

removing the stripe from the recently modified list in response to recalculating the at least one checksum using all the data blocks in the stripe.

20. The method of claim 17, further comprising

initiating a background operation to read the data blocks and the at least one checksum in each stripe for a plurality of addressable blocks to determine if the at least one checksum data is accurate, wherein the plurality of addressable blocks on which to perform the background operation includes modified and unmodified data.

21. The method of claim 20, further comprising:

alternating between processing m stripes as part of the background operation and n stripes as part of the error checking operation processing modified addressable blocks indicated in the modified list, wherein m is greater than n.