Method of and system for protecting data during conversion from an ECC protection scheme to a parity protection scheme

• US 7,954,034 B1
• Filed: 09/30/2005
• Issued: 05/31/2011
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Curry, Clayton A., Campbell, Brian K.
• Primary Examiner(s): Baderman; Scott T
• Assistant Examiner(s): Ahmed; Enam
• Application Number:
  US11/241,167
• Time in Patent Office: 2,069 Days
• Field of Search: 714/758
• US Class Current: 714/758
• CPC Class Codes: H03M 13/13 Linear codes
• CPC Class Codes: H03M 13/3776 using a re-encoding step during the decoding process

Abstract

A method of protecting data during transmission from an ECC protection scheme to a parity protection scheme, including reading a data word and an associated ECC from an upstream device; generating parity for the data word; generating a new ECC from the data word; computing a syndrome of the associated ECC and the new ECC; determining, based on the syndrome, if an error is present in the data word or the associated ECC; correcting a correctable error in the data word; correcting the parity for the data word; and transmitting the corrected data word and the corrected parity for the data word to a downstream device.

Claims

1. A method of protecting data during transmission from an ECC protection scheme to a parity protection scheme, the method comprising:

A. reading a data word and an associated ECC from an upstream device;

B. generating parity for the data word;

C. generating a new ECC from the data word;

D. computing a syndrome of the associated ECC and the new ECC;

E. determining, based on the syndrome, if an error is present in the data word or the associated ECC;

F. generating a correction mask from the syndrome upon detecting a correctable error in the data word;

G. correcting the correctable error in the data word, including comparing the data word to the correction mask to generate a corrected data word;

H. correcting the parity for the data word, including comparing the parity to a form of the correction mask to generate a corrected parity; and

I. transmitting the corrected data word and the corrected parity for the data word to a downstream device.

2. The method of claim 1 wherein Step D includes performing an XOR operation on the associated ECC and the new ECC.

3. The method of claim 1 wherein comparing the data word to the correction mask to generate the corrected data word comprises performing an XOR operation on the data word and the correction mask.

4. The method of claim 1 wherein the form of the correction mask is generated by performing a reduction XOR operation on the correction mask.

5. The method of claim 1 wherein, in Step E, if no error is detected, the data word and the parity are transmitted to the downstream device.

6. The method of claim 1 wherein, if an error is detected in Step E, the method further includes determining whether the error is correctable.

7. The method of claim 6 wherein, if the error is determined to be not correctable, the data word and the parity are transmitted to the downstream device.

8. A method of protecting data during transmission from an ECC protection scheme to a parity protection scheme, the method comprising:

A. reading a data word and an associated ECC from an upstream device;

B. generating parity for the data word;

C. performing an error check operation on the associated ECC by generating a new ECC from the data word, computing a syndrome of the associated ECC and the new ECC and determining, based on the syndrome, if an error is present in the data word or the associated ECC;

D. generating a correction mask from the syndrome upon detecting a correctable error in the data word;

E. correcting the correctable error in the data word, including comparing the data word to the correction mask to generate a corrected data word;

F. correcting the parity for the data word, including comparing the parity to a form of the correction mask to generate a corrected parity; and

G. transmitting the corrected data word and the corrected parity for the data word to a downstream device.

9. The method of claim 8 wherein comparing the data word to the correction mask to generate the corrected data word comprises performing an XOR operation on the data word and the correction mask.

10. The method of claim 8 wherein the form of the correction mask is generated by performing a reduction XOR operation on the correction mask.

11. The method of claim 8 wherein, in Step C, if no error is detected, the data word and the parity are transmitted to the downstream device.

12. The method of claim 8 wherein, if an error is detected in Step C, the method further includes determining whether the error is correctable.

13. The method of claim 12 wherein, if the error is determined to be not correctable, the data word and the parity are transmitted to the downstream device.