End-to end data protection supporting multiple CRC algorithms

• US 9,201,724 B2
• Filed: 04/30/2012
• Issued: 12/01/2015
• Est. Priority Date: 08/23/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Butt, Kevin D., Seger, Paul J.
• Primary Examiner(s): Alphonse, Fritz
• Application Number:
  US13/459,417
• Publication Number:
  US 20130055054A1
• Time in Patent Office: 1,310 Days
• Field of Search: 714/807, 714/759, 714/781, 714/751, 714/733, 714/701
• US Class Current: 1/1
• 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: G11B 20/1201 on tapes
• 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: G11B 2020/1843 using a cyclic redundancy check [CRC]
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H03M 13/2909 Product codes
• CPC Class Codes: H03M 13/3707 Adaptive decoding and hybrid decoding, e.g. decoding methods or techniques providing more than one decoding algorithm for one code
• CPC Class Codes: H03M 13/6511 Support of multiple decoding rules, e.g. combined MAP and Viterbi decoding
• CPC Class Codes: H03M 13/6516 Support of multiple code parameters, e.g. generalized Reed-Solomon decoder for a variety of generator polynomials or Galois fields

Abstract

A technique for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms includes receiving a data block protected by a first CRC. The first CRC is generated using a first CRC algorithm. The integrity of the data block is checked using the first CRC and the first CRC algorithm. A second CRC for the data block is then computed using a second CRC algorithm different from the first CRC algorithm. The data block, first CRC, and second CRC are stored on a storage medium, such as magnetic tape.

Claims

1. A method for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms, the method comprising:

receiving, by a storage device from a first host device, a data block protected by a first CRC, the first CRC generated by a first CRC algorithm;

checking, by the storage device, the integrity of the data block using the first CRC and the first CRC algorithm;

computing, by the storage device, a second CRC for the data block using a second CRC algorithm different from the first CRC algorithm; and

storing, by the storage device, the data block, the first CRC, and the second CRC on a storage medium.

2. The method of claim 1, further comprising receiving, by the storage device, an indication from the first host device that the first CRC was generated using the first CRC algorithm.

3. The method of claim 1, further comprising requesting, by a second host device, the data block on the storage medium.

4. The method of claim 3, further comprising specifying, by the second host device, which of the first and second CRC algorithms the second host device is using.

5. The method of claim 4, further comprising:

if the second host device is using the first CRC algorithm, checking, by the storage device, the integrity of the data block using the first CRC; and

if the second host device is using the second CRC algorithm, checking, by the storage device, the integrity of the data block using the second CRC.

6. The method of claim 5, further comprising:

if the second host device is using the first CRC algorithm, additionally checking, by the storage device, the integrity of the data block using the second CRC; and

if the second host device is using the second CRC algorithm, additionally checking, by the storage device, the integrity of the data block using the first CRC.

7. The method of claim 4, further comprising:

if the second host device is using the first CRC algorithm, returning, by the storage device, the first CRC with the data block to the second host device; and

if the second host device is using the second CRC algorithm, returning, by the storage device, the second CRC with the data block to the second host device.

8. The method of claim 1, further comprising storing, by the storage device, a CRC algorithm identifier with the data block identifying the CRC algorithm the first host device is using.

9. The method of claim 8, wherein computing the second CRC comprises computing the second CRC to protect both the data block and the CRC algorithm identifier together.

10. The method of claim 9, further comprising, in the event a second host device requests the data block with the second CRC, recomputing, by the storage device, the second CRC to protect the data block only, and returning the data block and the recomputed second CRC to the second host device.

11. The method of claim 1, wherein the first and second CRCs are stored on the storage medium in a consistent order.

12. The method of claim 1, wherein the storage medium is magnetic tape.

13. An apparatus for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms, the apparatus comprising:

a storage device to receive, from a first host device, a data block protected by a first CRC, the first CRC generated by a first CRC algorithm;

the storage device further configured to check the integrity of the data block using the first CRC and the first CRC algorithm;

the storage device further configured to compute a second CRC for the data block using a second CRC algorithm different from the first CRC algorithm; and

the storage device further configured to store the data block, the first CRC, and the second CRC on a storage medium.

14. The apparatus of claim 13, wherein the storage device is further configured to receive an indication from the first host device that the first CRC was generated using the first CRC algorithm.

15. The apparatus of claim 13, wherein the storage device is further configured to receive, from a second host device, a request for the data block on the magnetic tape medium.

16. The apparatus of claim 15, wherein the storage device is further configured to receive, from the second host device, an indication of which of the first and second CRC algorithms the second host device is using.

17. The apparatus of claim 16, wherein the storage device is further configured to:

check the integrity of the data block using the first CRC if the second host device is using the first CRC algorithm; and

check the integrity of the data block using the second CRC if the second host device is using the second CRC algorithm.

18. The apparatus of claim 17, wherein the storage device is further configured to:

additionally check the integrity of the data block using the second CRC if the second host device is using the first CRC algorithm; and

additionally check the integrity of the data block using the first CRC if the second host device is using the second CRC algorithm.

19. The apparatus of claim 16, wherein the storage device is further configured to:

return, to the second host device, the first CRC with the data block if the second host device is using the first CRC algorithm; and

return, to the second host device, the second CRC with the data block if the second host device is using the second CRC algorithm.

20. The apparatus of claim 13, wherein the storage device is further configured to store a CRC algorithm identifier with the data block identifying the CRC algorithm the first host device is using.

21. The apparatus of claim 20, wherein the storage device is further configured to compute the second CRC to protect both the data block and the CRC algorithm identifier together.

22. The apparatus of claim 21, wherein the storage device is further configured to, in the event a second host device requests the data block with the second CRC, recompute the second CRC to protect the data block only, and return the data block and the recomputed second CRC to the second host device.

23. The apparatus of claim 13, wherein the first and second CRCs are stored on the storage medium in a consistent order.

24. The apparatus of claim 13, wherein the storage device is a tape drive.

25. The apparatus of claim 13, wherein the storage medium is magnetic tape.