Method and system for detection and reconstruction of corrupted data in a data storage subsystem

• US 5,951,691 A
• Filed: 05/16/1997
• Issued: 09/14/1999
• Est. Priority Date: 05/16/1997
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ng, Chan Yiu, Chen, James C., Lanzi, Charles Richard
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): Iqbal, Nadeem
• Application Number:
  US08/857,890
• Time in Patent Office: 851 Days
• Field of Search: 395/182.03, 395/182.04, 395/182.06, 395/182.11, 395/183.18, 395/183.19, 395/183.2, 395/185.01, 395/482.04, 395/578, 371/40.11, 371/40.2, 371/40.15, 714/5, 714/8, 714/15, 714/20, 714/21, 714/25, 714/37, 714/44, 714/770, 714/771, 714/819
• US Class Current: 714/5.11
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 11/201 between storage system components
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations
• CPC Class Codes: G06F 2211/1064 Parity-single bit-RAID3, i.e. RAID 3 implementations

Abstract

The present invention provides a method and system for detecting corrupted data of a plurality of hard disk drives (HDDs) in a data storage subsystem. In this system a predetermined number of fixed blocks within each of the HDDs emulate a track of a first track format. The predetermined number of fixed blocks provide a logical track. The logical track of one of the plurality of HDDs is generated by the others of the plurality of HDDs. The plurality of logical tracks forming a plurality of track groups. In a first aspect the method and system comprises assigning each of the plurality of logical tracks an address translation (ADT) number, comparing each of the ADT numbers of the plurality of logical tracks to an expected value until a mismatch occurs in a logical track, and determining if other logical tracks in a same track group have accurate ADT numbers. The first aspect further includes reconstructing the logical track if the other tracks within the same track group have accurate ADT numbers. In a second aspect the method and system comprises determining each of the plurality of logical tracks is formatted in accordance with first track format, comparing each of the formats of the plurality of logical tracks to the expected format until a mismatch occurs in a logical track, and determining if other logical tracks in a same track group have accurate first track formats. The second aspect includes reconstructing the logical track if the other tracks within the same track group have accurate first formats.

Claims

1. A method for detecting corrupted data in one of a plurality of hard disk drives (HDDS) in a data storage subsystem, a predetermined number of fixed blocks within each of the HDDs emulating a track of a first track format, the predetermined number of fixed blocks providing a logical track, the logical track of one of the plurality of HDDs being generated by the others of the plurality of HDDs, the plurality of logical tracks forming a plurality of track groups;

the method comprising the steps of;

a) assigning each of the plurality of logical tracks an address translation (ADT) number;

b) comparing each of the ADT numbers of the plurality of logical tracks to an expected value until a mismatch occurs in a logical track;

c) determining if other logical tracks in a same track group have accurate ADT numbers; and

d) reconstructing the logical track if the other tracks within the same track group have accurate ADT numbers.

2. The method of claim 1 in which the corrupted data is detected during a background scan.

3. The method of claim 1 in which the corrupted data is detected when the corrupted data is read by the data storage subsystem.

4. The method of claim 1 in which the first format comprises CKD format.

5. The method of claim 1 in which the processing system comprises a RAID-5 system.

6. The method of claim 1 which further includes the steps of:

(e) determining if the reconstructed logical track has an accurate ADT number; and

(f) rewriting the reconstructed logical track on the HDD if the ADT number is accurate.

7. The method of claim 1 in which the one of the plurality of HDDs being a parity HDD.

8. The method of claim 1 in which the others of the plurality of HDDs being the data HDDs.

9. A method for detecting corrupted data in one of a plurality of hard disk drives (HDDs) in a data storage subsystem, a predetermined number of fixed blocks within each of the HDDs emulating a track of a first track format, the predetermined number of fixed blocks providing a logical track, the logical track of one of the plurality of HDDs being generated by the others of the plurality of HDDs, the plurality of logical tracks forming a plurality of track groups;

the method comprising the steps of;

a) determining each of the plurality of logical tracks is formatted in accordance with an expected first track format;

b) comparing each of the formats of the plurality of logical tracks to the expected first track format until one of the logical tracks has an invalid format;

c) determining if other logical tracks in a same track group have valid first track formats; and

d) reconstructing the logical track if the other tracks within the same track group have valid first track formats.

10. The method of claim 9 in which the corrupted data is detected during a background scan.

11. The method of claim 9 in which the corrupted data is detected when the corrupted data is read by the data storage subsystem.

12. The method of claim 9 in which the processing system comprises a RAID-5 system.

13. The method of claim 9 in which the first format comprises CKD format.

14. The method of claim 13 wherein validity is determined by utilizing the CKD ECC.

15. The method of claim 13 wherein validity is determined by utilizing the CKD record content such as the physical address value of a record.

16. The method of claim 13 wherein validity is determined by the correctness of the record format such as a correct record size.

17. The method of claim 13 which further includes the steps of:

(e) determining if the reconstructed logical track has a valid first format; and

(f) rewriting the reconstructed logical track on the HDD if the first track format is valid.

18. The method of claim 17 in which the one of the plurality of HDDs being a parity HDD.

19. The method of claim 17 in which the others of the plurality of HDDs being the data HDDs.

20. The method of claim 17 in which the determining step (a) comprises the step of determining if each record and field is located at a correction location within a logical track.

21. A method for detecting corrupted data in one of a plurality of hard disk drives (HDDs) in a data storage subsystem, a predetermined number of fixed blocks within each of the HDDs emulating a track of a first track format, the predetermined number of fixed blocks providing a logical track, the logical track of one of the plurality of HDDs being generated by the others of the plurality of HDDs, the plurality of logical tracks forming a plurality of track groups;

the method comprising the steps of;

a) regenerating the one track from the other logical track;

b) comparing the one track to the regenerated one track;

c) determining which of the plurality of HDDs includes corrupted information if mismatch occurs; and

d) reconstructing the information in the HDD which includes corrupted data.

22. The method of claim 21 in which the corrupted data is detected during a background scan.

23. The method of claim 21 in which the corrupted data is detected when the corrupted data is read by the data storage subsystem.

24. The method of claim 21 in which the one of the plurality of HDDs being a parity HDD.

25. The method of claim 21 in which the others of the plurality of HDDs being the data HDDs.

26. A system for detecting corrupted data in one of a plurality of hard disk drives (HDDs) in a data storage subsystem, a predetermined number of fixed blocks within each of the HDDs emulating a track of a first track format, the predetermined number of fixed blocks providing a logical track, the logical track of one of the plurality of HDDs being generated by the others of the plurality of HDDs, the plurality of logical tracks forming a plurality of track groups;

the system comprising;

means for assigning each of the plurality of logical tracks an address translation (ADT) number;

means for comparing each of the ADT numbers of the plurality of logical tracks to an expected value until a mismatch occurs in a logical track;

means for determining if other logical tracks in a same track group have accurate ADT numbers; and

means for reconstructing the logical track if the other tracks within the same track group have accurate ADT numbers.

27. The system of claim 26 in which the corrupted data is detected during a background scan.

28. The system of claim 26 in which the corrupted data is detected when the corrupted data is read by the data storage subsystem.

29. The system of claim 26 which in which the first format comprises CKD format.

30. The system of claim 26 in which the processing system comprises a RAID-5 system.

31. The system of claim 26 which further includes:

means for determining if the reconstructed logical track has an accurate ADT number; and

means for rewriting the reconstructed logical track on the HDD if the ADT number is accurate.

32. The system of claim 26 in which the one of the plurality of HDDs being a parity HDD.

33. The system of claim 26 in which the others of the plurality of HDDs being the data HDDs.

34. A system for detecting corrupted data in one of a plurality of hard disk drives (HDDs) in a data storage subsystem, a predetermined number of fixed blocks within each of the HDDs emulating a track of a first track format, the predetermined number of fixed blocks providing a logical track, the logical track of one of the plurality of HDDs being generated by the others of the plurality of HDDs, the plurality of logical tracks forming a plurality of track groups;

the system comprising;

means for determining each of the plurality of logical tracks is formatted in accordance with an expected first track format;

means for comparing each of the formats of the plurality of logical tracks to the expected first track format until one of the logical tracks has an invalid format;

means for determining if other logical tracks in a same track group have valid first track formats; and

means for reconstructing the logical track if the other tracks within the same track group have valid first track formats.

35. The system of claim 34 in which the corrupted data is detected during a background scan.

36. The system of claim 34 in which the corrupted data is detected when the corrupted data is read by the data storage subsystem.

37. The system of claim 34 in which the processing system comprises a RAID-5 system.

38. The system of claim 34 in which the first format comprises CKD format.

39. The system of claim 38 wherein validity is determined by utilizing the CKD ECC.

40. The system of claim 38 wherein validity is determined by utilizing the CKD record content such as the physical address value of a record.

41. The system of claim 38 wherein validity is determined by the correctness of the record format such as a correct record size.

42. The system of claim 34 which further includes:

means for determining if the reconstructed logical track has a valid first format; and

means for rewriting the reconstructed logical track on the HDD if the first track format is valid.

43. The system of claim 42 in which the one of the plurality of HDDs being a parity HDD.

44. The system of claim 42 in which the others of the plurality of HDDs being the data HDDs.

45. The system of claim 42 in which the determining means comprises means for determining if each record and field is located at a correction location within a logical track.

46. A system for detecting corrupted data in one of a plurality of hard disk drives (HDDs) in a data storage subsystem, a predetermined number of fixed blocks within each of the HDDs emulating a track of a first track format, the predetermined number of fixed blocks providing a logical track, the logical track of one of the plurality of HDDs being generated by the others of the plurality of HDDs, the plurality of logical tracks forming a plurality of track groups;

the system comprising the steps of;

means for regenerating the one track from the other logical track;

means for comparing the one track to the regenerated one track;

means for determining which of the plurality of HDDs includes corrupted information if mismatch occurs; and

means for reconstructing the information in the HDD which includes corrupted data.

47. The system of claim 46 in which the corrupted data is detected during a background scan.

48. The system of claim 46 in which the corrupted data is detected when the corrupted data is read by the data storage subsystem.

49. The system of claim 46 in which the one of the plurality of HDDs being a parity HDD.

50. The system of claim 46 in which the others of the plurality of HDDs being the data HDDs.