END-TO-END DATA PROTECTION SUPPORTING MULTIPLE CRC ALGORITHMS

• US 20130055054A1
• Filed: 04/30/2012
• Published: 02/28/2013
• 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.
• Granted Patent: US 9,201,724 B2
• Time in Patent Office: Days
• US Class Current: 714/807
• 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 method for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms is disclosed. In one embodiment, such a method includes receiving, from a first host device, a data block protected by a first CRC. The first CRC is generated using a first CRC algorithm. The method checks the integrity of the data block using the first CRC and the first CRC algorithm. The method then computes a second CRC for the data block using a second CRC algorithm different from the first CRC algorithm. The method then stores the data block, the first CRC, and the second CRC 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, from a first host device, a data block protected by a first CRC, the first CRC generated by a first CRC algorithm;

checking the integrity of the data block using the first CRC and the first CRC algorithm;

computing a second CRC for the data block using a second CRC algorithm different from the first CRC algorithm; and

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

2. The method of claim 1, further comprising receiving 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 magnetic tape 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 the integrity of the data block using the first CRC; and

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

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

8. The method of claim 1, further comprising storing 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 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.