Method and apparatus for performing force unit access writes on a disk

• US 8,990,493 B1
• Filed: 06/30/2011
• Issued: 03/24/2015
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Neppalli, Srinivas, Jones, Brian E., Yu, Raymond
• Primary Examiner(s): Faal, Baboucarr
• Application Number:
  US13/174,547
• Time in Patent Office: 1,363 Days
• Field of Search: None
• US Class Current: 711/113
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache

Abstract

A disk drive comprising a rotatable disk, a head actuated over the disk, and a controller is disclosed. The controller is configured to write a first force unit access write data to the cache as part of the cache data, write the first force unit access write data and a first metadata corresponding to the first force unit access write data to the first location by using the head, transmit a first write complete status to a host, and maintain the first force unit access write data in the cache as part of the cache data. The controller is also configured to store write data as part of the cache data. Furthermore, the controller is configured to write the cache data to a third location, and a metadata corresponding to the cache data to the disk.

Claims

1. A disk drive comprising:

a rotatable disk including a plurality of tracks having a first location, a second location, and a third location different from the first location and the second location;

a head actuated over the disk;

a cache configured to store cache data; and

a controller configured to;

receive a first force unit access write command from a host;

write a first force unit access write data to the cache as part of the cache data,

write the first force unit access write data and a first metadata corresponding to the first force unit access write data to the first location by using the head,

transmit a first write complete status to the host,

maintain the first force unit access write data in the cache as part of the cache data,

write a write data to the cache as part of the cache data,

maintain the write data in the cache as part of the cache data,

write the cache data including the first force unit access data and the write data to the third location, and

write a second metadata corresponding to the first force unit access write data and the write data to the disk.

2. The disk drive of claim 1, wherein the write data comprises a second force unit access write data and the controller is further configured to:

write the second force unit access write data to the cache as part of the cache data,

write the second force unit access write data and a third metadata corresponding to the second force unit access write data to the second location by using the head, and

transmit a second write complete status to the host.

3. The disk drive of claim 2 wherein the controller is further configured to receive a second force unit access write command from the host.

4. The disk drive of claim 2 wherein the second metadata is written to the third location.

5. The disk drive of claim 4 wherein the first location and the second location are part of a first shingled zone, and the third location is part of a second shingled zone different from the first shingled zone.

6. The disk drive of claim 5 wherein the first shingled zone is a shingled zone allocated for force unit access write data.

7. The disk drive of claim 5 wherein the controller is further configured to determine that the first shingled zone is a shingled zone located closest to a position of the head when the controller received a force unit access write command from the host.

8. The disk drive of claim 5 wherein the rotatable disk stores a valid data counter corresponding to the first shingled zone, and after the cache data and the second metadata is written to the second shingled zone, the controller is further configured to decrement the valid data counter corresponding to the first shingled zone.

9. The disk drive of claim 4 wherein the rotatable disk stores a mapping table, and the controller is further configured to update the mapping table after the controller writes the cache data and the second metadata to the third location.

10. The disk drive of claim 4 wherein the plurality of tracks stores a valid data counter corresponding to a segment of the plurality of tracks, wherein the first location and the second location are located in the segment.

11. The disk drive of claim 10 wherein after the cache data and the second metadata are written to the third location, the controller is further configured to decrement the valid data counter corresponding to the segment.

12. The disk drive of claim 4 wherein the plurality of tracks stores a first valid data counter corresponding to a first segment of the plurality of tracks, and a second valid data counter corresponding to a second segment of the plurality of tracks, wherein the first location is located in the first segment, and the second location is located in the second segment.

13. The disk drive of claim 12 wherein after the cache data and the second metadata are written to the third location, the controller is further configured to decrement the first valid data counter and the second valid data counter.

14. The disk drive of claim 1 wherein the controller is further configured to write the cache data to the third location during a cache flush.

15. The disk drive of claim 14 wherein the third location is selected to be located sequentially after a location in the plurality of tracks that the head was performing a write operation on before the cache flush.

16. A method for writing force unit access write data to a cache and a disk including a first location, a second location, and a third location different from the first location and the second location comprising:

receiving a first force unit access write command from a host;

writing a first force unit access write data to a cache as part of a cache data;

writing the first force unit access write data and a first metadata corresponding to the first force unit access write data to the first location on the disk;

transmitting a first write complete status to the host;

maintaining the first force unit access write data in the cache as part of the cache data;

writing a write data to the cache as part of the cache data;

maintaining the write data in the cache as part of the cache data;

writing the cache data including the first force unit access write data and the write data to the third location on the disk; and

writing a second metadata corresponding to the first force unit access write data and the write data to the disk.

17. The method of claim 16 wherein the write data comprises a second force unit access write data.

18. The method of claim 17 further comprising:

writing the second force unit access write data to the cache as part of the cache data;

writing the second force unit access write data and a third metadata corresponding to the second force unit access write data to the second location; and

transmitting a second write complete status to the host.

19. The method of claim 18 further comprising:

receiving a second force unit access write command from the host.

20. The method of claim 18 wherein the second metadata is written to the third location.

21. The method of claim 20 wherein the first location and the second location are part of a first shingled zone and the third location is part of a second shingled zone different from the first shingled zone.

22. The method of claim 21 wherein the first shingled zone is a shingled zone allocated for force unit access write data.

23. The method of claim 22 wherein the first shingled zone is a shingled zone located closest to a position of a head actuated over the disk, when a controller received a force unit access write command from the host.

24. The method of claim 21 further comprising decrementing a valid data counter corresponding to the first shingled zone, after the cache data and the second metadata are written to the second shingled zone.

25. The method of claim 18 further comprising updating a mapping table after the cache data and the second metadata are written to the third location.

26. The method of claim 18 further comprising decrementing a valid data counter corresponding to a segment containing the first location and the second location, after the cache data and the third metadata are written to the third location.

27. The method of claim 18 further comprising decrementing a first valid data counter corresponding to a first segment containing the first location and decrementing a second valid data counter corresponding to a second segment containing the second location, after the cache data and the second metadata are written to the third location.

28. The method of claim 16 wherein the step of writing the cache data to the third location on the disk includes writing the cache data to the third location during a cache flush.

29. The method of claim 28 further comprising selecting the third location to be located sequentially after a location in a plurality of tracks of the disk that a head actuated over the disk was performing a write operation on before the cache flush.