DISK DRIVE REFRESHING ZONES IN SEGMENTS TO SUSTAIN TARGET THROUGHPUT OF HOST COMMANDS

• US 20090027799A1
• Filed: 07/27/2007
• Published: 01/29/2009
• Est. Priority Date: 07/27/2007
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: ROTHBERG, MICHAEL S., TSAI, CHUN SEI, BOYLE, WILLIAM B.
• Granted Patent: US 7,945,727 B2
• Time in Patent Office: Days
• US Class Current: 360/75
• CPC Class Codes: G11B 19/045 by detecting mistracking
• CPC Class Codes: G11B 5/5539 Skew adjustment, e.g. adjustment of the position of the first sector in each track with respect to the other tracks, for improving, e.g. access performance
• CPC Class Codes: G11B 5/59655 Sector, sample or burst servo format

Abstract

A disk drive is disclosed including a disk comprising a plurality of refresh zones, and a head actuated over the disk. The disk drive further comprises control circuitry for receiving access commands from a host. The control circuitry refreshes a refresh zone in a plurality of segments with an interval between each segment, and processes at least one of the access commands during the interval between at least two of the segments, wherein a size of each segment and the interval ensures an average throughput of access commands received from the host does not fall below a first threshold.

Claims

1. A disk drive comprising:

a disk comprising a plurality of refresh zones;

a head actuated over the disk; and

control circuitry operable to;

receive access commands from a host;

refresh one of the refresh zones in a plurality of segments with an interval between each segment; and

process at least one of the access commands during the interval between at least two of the segments;

wherein a size of each segment and the interval ensures an average throughput of access commands received from the host does not fall below a first threshold.

2. The disk drive as recited in claim 1, wherein the average throughput of access commands is substantially equal to the number of access commands received per second.

3. The disk drive as recited in claim 1, wherein at least one of the refresh zones comprises a plurality of tracks.

4. The disk drive as recited in claim 1, wherein:

the tracks form a plurality of physical zones; and

the segment size is selected relative to the physical zones.

5. The disk drive as recited in claim 4, wherein:

each track comprises a plurality of data sectors; and

the segment size is selected relative to a number of data sectors per track within each physical zone.

6. The disk drive as recited in claim 4, wherein:

each track comprises a plurality of data sectors;

a number of skew data sectors is associated with a contiguous access pattern when switching tracks within one of the physical zones; and

the segment size is selected relative to the number of skew data sectors.

7. The disk drive as recited in claim 4, wherein:

each track comprises a plurality of data sectors;

a number of skew data sectors is associated with a contiguous access pattern when switching tracks within one of the physical zones; and

the segment size is selected relative to a number of data sectors per track and the number of skew data sectors within each physical zone.

8. The disk drive as recited in claim 1, wherein the control circuitry is further operable to:

maintain a first priority queue of refresh zones scheduled to be refreshed using a first interval between segments; and

maintain a second priority queue of refresh zones scheduled to be refreshed using a second interval between segments, wherein the second interval is shorter than the first interval.

9. The disk drive as recited in claim 8, wherein:

a duration of the first interval ensures an average throughput of access commands received from the host does not fall below the first threshold; and

a duration of the second interval ensures an average throughput of access commands received from the host does not fall below a second threshold less than the first threshold.

10. The disk drive as recited in claim 8, wherein the control circuitry is further operable to:

maintain a refresh monitor for each refresh zone; and

transfer one of the refresh zones held in the first priority queue to the second priority queue if the corresponding refresh monitor exceeds a threshold.

11. The disk drive as recited in claim 1, wherein the control circuitry is further operable to adjust the interval.

12. The disk drive as recited in claim 11, wherein the control circuitry is further operable to:

maintain a command queue of access commands received from the host; and

adjust the interval based on a number of access commands in the command queue.

13. The disk drive as recited in claim 11, wherein the control circuitry is further operable to:

maintain a refresh queue of refresh zones scheduled to be refreshed; and

adjust the interval based on a number of refresh zones in the refresh queue.

14. The disk drive as recited in claim 11, wherein the first threshold changes in response to the adjusted interval.

15. A method of operating a disk drive, the disk drive as comprising a disk including a plurality of refresh zones, and a head actuated over the disk, the method comprising:

receiving access commands from a host;

refreshing one of the refresh zones in a plurality of segments with an interval between each segment; and

processing at least one of the access commands during the interval between at least two of the segments;

wherein a size of each segment and the interval ensures an average throughput of access commands received from the host does not fall below a first threshold.

16. The method as recited in claim 15, wherein the average throughput of access commands is substantially equal to the number of access commands received per second.

17. The method as recited in claim 15, wherein at least one of the refresh zones comprises a plurality of tracks.

18. The method as recited in claim 15, wherein:

the tracks form a plurality of physical zones; and

the segment size is selected relative to the physical zones.

19. The method as recited in claim 18, wherein:

each track comprises a plurality of data sectors; and

the segment size is selected relative to a number of data sectors per track within each physical zone.

20. The method as recited in claim 18, wherein:

each track comprises a plurality of data sectors;

a number of skew data sectors is associated with a contiguous access pattern when switching tracks within one of the physical zones; and

the segment size is selected relative to the number of skew data sectors.

21. The method as recited in claim 18, wherein:

each track comprises a plurality of data sectors;

a number of skew data sectors is associated with a contiguous access pattern when switching tracks within one of the physical zones; and

the segment size is selected relative to a number of data sectors per track and the number of skew data sectors within each physical zone.

22. The method as recited in claim 15, further comprising:

maintaining a first priority queue of refresh zones scheduled to be refreshed using a first interval between segments; and

maintaining a second priority queue of refresh zones scheduled to be refreshed using a second interval between segments, wherein the second interval is shorter than the first interval.

23. The method as recited in claim 22, wherein:

a duration of the first interval ensures an average throughput of access commands received from the host does not fall below the first threshold; and

a duration of the second interval ensures an average throughput of access commands received from the host does not fall below a second threshold less than the first threshold.

24. The method as recited in claim 22, further comprising:

maintaining a refresh monitor for each refresh zone; and

transferring one of the refresh zones held in the first priority queue to the second priority queue if the corresponding refresh monitor exceeds a threshold.

25. The method as recited in claim 15, further comprising adjusting the interval.

26. The method as recited in claim 25, further comprising

maintaining a command queue of access commands received from the host;

and

adjusting the interval based on a number of access commands in the command queue.

27. The method as recited in claim 25, further comprising:

maintaining a refresh queue of refresh zones scheduled to be refreshed; and

adjusting the interval based on a number of refresh zones in the refresh queue.

28. The method as recited in claim 25, wherein the first threshold changes in response to the adjusted interval.

29. A disk drive as comprising:

a disk comprising a plurality of refresh zones;

a head actuated over the disk;

a means for receiving access commands from a host;

a means for refreshing one of the refresh zones in a plurality of segments with an interval between each segment; and

a means for processing at least one of the access commands during the interval between at least two of the segments;

wherein a size of each segment and the interval ensures an average throughput of access commands received from the host does not fall below a first threshold.