Error detection using data block mapping

• US 20030221155A1
• Filed: 05/24/2002
• Published: 11/27/2003
• Est. Priority Date: 05/24/2002
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Weibel, David C., Duncan, William L.
• Granted Patent: US 7,036,066 B2
• Time in Patent Office: Days
• US Class Current: 714/752
• CPC Class Codes: G11B 20/12 Formatting, e.g. arrangement of data block or words on the record carriers within interface between computers and data recorders G06F3/06
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: H03M 13/05 using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits H03M13/2906 takes precedence

Abstract

Error detection using data block mapping is provided. One method includes receiving a write request to write a user data block having a first block size, generating an error detection code for the user data block, appending the error detection code to the user data block to form an extended data block, and mapping the extended data block to a plurality of actual data blocks, each actual data block having a block size equal to the first block size.

Claims

1. A method for error detection using data block mapping, comprising:

receiving a write request to write a user data block having a first block size;

generating an error detection code for the user data block;

appending the error detection code to the user data block to form an extended data block; and

mapping the extended data block to a plurality of actual data blocks, each actual data block having a block size equal to the first block size.

2. The method of claim 1, further comprising:

transmitting the plurality of actual data blocks to a storage device.

3. The method of claim 2, further comprising:

storing the plurality of actual data blocks on the storage device.

4. The method of claim 3, wherein:

said storing the plurality of actual data blocks on the storage device comprises storing the plurality of actual data blocks in adjacent physical locations on the storage device

5. The method of claim 1, wherein:

said generating the error detection code for the user data block comprises one of the following;

generating an XOR checksum of the user data block;

or

generating a CRC checksum of the user data block

6. The method of claim 1, wherein:

said mapping the extended data block to the plurality of actual data blocks comprises;

mapping a first segment of the extended data block to a first actual data block, wherein the first actual data block comprises a first portion and a second portion such that said first segment of the extended data block is mapped to the second portion of the first actual data block; and

mapping a second segment of the extended data block to a second actual data block, wherein the second actual data block comprises a first portion and a second portion such that said second segment of the extended data block is mapped to the first portion of the second actual data block.

7. The method of claim 6, further comprising:

retrieving existing data from the first and second actual data blocks on a storage device; and

transmitting the first and second actual data blocks to the storage device to be stored, wherein;

the first portion of the first actual data block includes the existing data retrieved from the first actual data block and the second portion of the first actual data block includes the first segment of the extended data block; and

the first portion of the second actual data block includes the existing data retrieved from the second actual data block and the second portion of the second actual data block includes the second segment of the extended data block.

8. The method of claim 1, further comprising:

receiving a read request to read the user data block from the storage device;

identifying the plurality of actual data blocks mapped to the extended data block corresponding to the requested user data block;

retrieving the identified plurality of actual data blocks from the storage device; and

extracting the extended data block from the identified plurality of actual data blocks retrieved from the storage device.

9. The method of claim 8, further comprising:

verifying that the extracted data block extracted from the plurality of actual data blocks is free from data integrity errors.

10. The method of claim 9, wherein:

said verifying that the extracted data block extracted from the plurality of actual data blocks does not contain a data integrity error comprises;

calculating a confirmation error detection code from the extended data block extracted from the plurality of actual data blocks retrieved from the storage device; and

comparing the confirmation error detection code with the error detection code contained in the extended data block.

11. The method of claim 10, further comprising:

reporting a data integrity error if the confirmation error detection code does not correspond with the error detection code contained in the extended data block.

12. A computer system for error detection in storage data using data block mapping, comprising:

an application layer configured to generate write requests, each write request comprising a request to store a user data block having a first block size;

an error correction code generation layer configured to receive the write requests from the application, said error correction code generation layer further configured to generate an error detection code for the user data block and append the error detection code to the user data block to form an extended data block; and

a data mapping layer configured to map the extended data block to a plurality of actual data blocks, each actual data block having a block size equal to the first block size.

13. The system of claim 12, further comprising:

a storage device driver layer configured to transmit the plurality of actual data blocks to a storage device.

14. The system of claim 13, further comprising:

a storage device configured to store the plurality of actual data blocks on the storage device.

15. The system of claim 14, wherein:

said storage device is further configured to store the plurality of actual data blocks in adjacent physical locations on the storage device

16. The system of claim 12, wherein:

said error correction code generation layer is further configured to generate the error detection code using one of the following techniques;

an XOR checksum of the user data block;

or

a CRC checksum of the user data block.

17. The system of claim 12, wherein:

said data mapping layer is further configured to;

map a first segment of the extended data block to a first actual data block, wherein the first actual data block comprises a first portion and a second portion such that said first segment of the extended data block is mapped to the second portion of the first actual data block; and

map a second segment of the extended data block to a second actual data block, wherein the second actual data block comprises a first portion and a second portion such that said second segment of the extended data block is mapped to the first portion of the second actual data block.

18. The system of claim 17, wherein:

said data mapping layer is further configured to retrieve existing data from the first and second actual data blocks on a storage device and transmit the first and second actual data blocks to the storage device layer, wherein;

the first portion of the first actual data block includes the existing data retrieved from the first actual data block and the second portion of the first actual data block includes the first segment of the extended data block; and

the first portion of the second actual data block includes the existing data retrieved from the second actual data block and the second portion of the second actual data block includes the second segment of the extended data block.

19. The system of claim 12, wherein:

said application layer is further configured to generate read requests, each read request comprising a request to retrieve the user data block having the first block size;

said data mapping layer is further configured to identify the plurality of actual data blocks mapped to the extended data block corresponding to the requested user data block;

said storage device driver layer is further configured to retrieve the identified plurality of actual data blocks from the storage device; and

said data mapping layer is further configured to extract the extended data block from the plurality of actual data blocks retrieved from the storage device.

20. The system of claim 19, wherein:

said error detection code generation layer is further configured to verify that the extracted data block extracted from the plurality of actual data blocks is free from data integrity errors.

21. The system of claim 20, wherein:

said error detection code generation layer is further configured to verify that the extracted data block extracted from the plurality of actual data blocks does not contain a data integrity error by calculating a confirmation error detection code from the extended data block extracted from the plurality of actual data blocks retrieved from the storage device and comparing the confirmation error detection code with the error detection code contained in the extended data block.

22. The system of claim 21, wherein:

said error detection code generation layer is further configured to report a data integrity error if the confirmation error detection code does not correspond with the error detection code contained in the extended data block.

23. A computer-readable medium containing instructions for storing data using error detection codes, wherein said instructions cause operations to be performed comprising:

receiving a write request to write a user data block having a first block size;

generating an error detection code for the user data block;

appending the error detection code to the user data block to form an extended data block; and

mapping the extended data block to a plurality of actual data blocks, each actual data block having a block size equal to the first block size.

24. The computer-readable medium of claim 23, wherein said instructions cause the further operation to be performed:

transmitting the plurality of actual data blocks to a storage device.

25. The computer-readable medium of claim 24, wherein said instructions cause the further operation to be performed:

storing the plurality of actual data blocks on the storage device.

26. The computer-readable medium of claim 25, wherein:

said storing the plurality of actual data blocks on the storage device comprises storing the plurality of actual data blocks in adjacent physical locations on the storage device

27. The computer-readable medium of claim 23, wherein:

said generating the error detection code for the user data block comprises one of the following;

generating an XOR checksum of the user data block;

generating a CRC checksum of the user data block

28. The computer-readable medium of claim 23, wherein:

said mapping the extended data block to the plurality of actual data blocks comprises;

mapping a first segment of the extended data block to a first actual data block, wherein the first actual data block comprises a first portion and a second portion such that said first segment of the extended data block is mapped to the second portion of the first actual data block; and

mapping a second segment of the extended data block to a second actual data block, wherein the second actual data block comprises a first portion and a second portion such that said second segment of the extended data block is mapped to the first portion of the second actual data block.

29. The computer-readable medium of claim 28, wherein said instructions cause the further operation to be performed:

retrieving existing data from the first and second actual data blocks on a storage device; and

transmitting the first and second actual data blocks to the storage device to be stored, wherein;

the first portion of the first actual data block includes the existing data retrieved from the first actual data block and the second portion of the first actual data block includes the first segment of the extended data block; and

the first portion of the second actual data block includes the existing data retrieved from the second actual data block and the second portion of the second actual data block includes the second segment of the extended data block.

30. The computer-readable medium of claim 23, wherein said instructions cause the further operation to be performed:

receiving a read request to read the user data block from the storage device;

identifying the plurality of actual data blocks mapped to the extended data block corresponding to the requested user data block;

retrieving the identified plurality of actual data blocks from the storage device; and

extracting the extended data block from the identified plurality of actual data blocks retrieved from the storage device.

31. The computer-readable medium of claim 30, wherein said instructions cause the further operation to be performed:

verifying that the extracted data block extracted from the plurality of actual data blocks is free from data integrity errors.

32. The computer-readable medium of claim 31, wherein:

said verifying that the extracted data block extracted from the plurality of actual data blocks does not contain a data integrity error comprises;

calculating a confirmation error detection code from the extended data block extracted from the plurality of actual data blocks retrieved from the storage device; and

comparing the confirmation error detection code with the error detection code contained in the extended data block.

33. The computer-readable medium of claim 32, wherein said instructions cause the further operation to be performed:

reporting a data integrity error if the confirmation error detection code does not correspond with the error detection code contained in the extended data block.