Background media scan for recovery of data errors

• US 7,490,261 B2
• Filed: 12/18/2003
• Issued: 02/10/2009
• Est. Priority Date: 12/18/2003
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Anderson, David A., Li, Xiaoying, Gaertner, Mark
• Primary Examiner(s): Bonzo; Bryce P
• Application Number:
  US10/740,886
• Publication Number:
  US 20050188238A1
• Time in Patent Office: 1,881 Days
• Field of Search: 714/8, 714/723, 714/769
• US Class Current: 714/6.13
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs

Abstract

The present invention is a method of recovering data in a system that stores data in identifiable storage segments. The method includes scanning at least one storage segment for a read error. The method also includes performing a read recovery operation in an attempt to recover a read error. The method logs recovered read errors as a function of the read recovery operation.

Claims

1. A method of recovering data in a storage system that stores data in identifiable storage segments, the method comprising:

scanning storage segments for read errors when the storage system is idle and performing at least one read recovery operation in an attempt to recover the read errors found during the scan;

receiving a write command while the storage segments are being scanned;

converting the write command to a write and verify command;

writing data to at least one of the storage segments in accordance with the write portion of the write and verify command;

verifying data written to the at least one storage segment in accordance with the verify portion of the write and verify command by;

reading the data written to the at least one storage segment; and

performing at least one read recovery operation on the data written to the at least one storage segment in an attempt to recover a read error from the data written.

2. The method of claim 1 and further comprising determining whether the storage system is ready to scan storage segments for read errors.

3. The method of claim 2, wherein determining whether the storage system is ready to scan storage segments for read errors further comprises determining whether a predetermined amount of interval time has elapsed since a last scan of the storage segments, wherein the predetermined interval is user selectable.

4. The method of claim 2, wherein determining whether the storage system is ready to scan the storage segments for read errors further comprises determining whether a predetermined amount of idle time has elapsed since the storage system was last active.

5. The method of claim 1, wherein step (a) further comprises setting a level of correction capability of read recovery such that the scanning can find marginally defective errors.

6. The method of claim 1, wherein step (b) further comprises disabling the scanning if a fatal error occurs.

7. The method of claim 1 and further comprising enabling the storage system to automatically reallocate selected storage segments having recovered and unrecovered read errors to spare storage segments.

8. The method of claim 1 and further comprising logging an occurrence of a recovered read error when scanning the storage segments for read errors if an amount of corrective routines to recover the read error exceeds a threshold amount of corrective routines and logging an occurrence of an unrecovered read error when scanning the storage segments for read errors if the attempt to recover the read error fails.

9. The method of claim 8, further comprising accessing the logging to view information related to recovered and unrecovered read errors.

10. The, method of claim 8, and further comprising erasing the logging such that there is additional space for logging of recovered and unrecovered read errors.

11. The method of claim 1, wherein the scanning of storage segments for read errors comprises a pre-scanning of the storage segments upon initial power-up of the storage system when the storage system is idle, wherein pre-scanning comprises a first scan of the storage segments.

12. The method of claim 11,wherein converting the write command to a write and verify command comprises converting the write command to a write and verify command when the write command is to one of the storage segments that has not undergone the pre-scanning.

13. The method of claim 1, further comprising:

performing at least one write recovery operation on the data written to the at least one storage segment from the write command portion of the write and verify command in attempt to recover a write error; and

logging an unrecovered write errors.

14. A storage system that stores data in storage segments comprises processing circuitry configured to:

scan storage segments for read errors when the storage system is idle;

perform at least one read recovery operation held in a memory of the processing circuitry in attempt to recover the read errors found during the scan;

log an occurrence of a recovered read error found during the scan if an amount of corrective routines to recover the read error exceeds a threshold amount of corrective routines;

receive a write command while the storage segments are being scanned;

convert the write command to a write and verify command;

write data to at least one of the storage segments in accordance with the write command;

verify data written to the at least one storage segment in accordance with the verify command by;

reading the data written to the at least one storage segment; and

performing at least one read recovery operation on the data written to the at least one storage segment in an attempt to recover a read error.

15. The system of claim 14, wherein the scan of storage segments for read errors comprises a pre-scan of the storage segments upon initial power-up of the storage system when the storage system is idle, wherein the pre-scan includes a first scan of the storage segments.

16. The system of claim 14, wherein the processing circuitry is further configured to convert the write command to a write and verify command when the write command is to one of the storage segments that has not undergone the pre-scan.

17. The system of claim 14 and further comprising a buffer configured to temporarily store unrecovered errors and recovered errors until they can be automatically reallocated to spare storage segments.

18. The method of claim 14, wherein the processing circuitry is further configured to perform at least one write recovery operation on the data written to the at least on storage segment in attempt to recover a write error if a write error occurred when writing the data.

19. A method of recovering data in a storage system that stores data in identifiable storage segments, the method comprising:

scanning storage segments for read errors when the storage system is idle;

receiving a write command while the storage segments are being scanned; and

converting the write command to a write and verify command, the write and verify command instructs the storage system to;

write data to at least one of the storage segments;

verify the data written to the at least one storage segment by reading the data written; and

perform at least one read recovery operation on the data written to the at least one storage segment in an attempt to recover an error found.

20. The method of claim 19, further comprising logging a recovered read error from the scanned storage segments if an amount of corrective routines to recover the read error exceeds a threshold amount of corrective routines.

21. The method of claim 19, wherein the write and verify command further instructs the storage system to perform at least one write recovery operation on the data written to the at least one storage segment in attempt to recover a write error if a write error occurred when writing the data.