Disk drive refreshing zones in segments to sustain target throughput of host commands

• US 7,945,727 B2
• Filed: 07/27/2007
• Issued: 05/17/2011
• Est. Priority Date: 07/27/2007
• Status: Expired due to Fees

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Tsai, Chun Sei, Rothberg, Michael S., Boyle, William B.
• Primary Examiner(s): Ellis; Kevin L
• Assistant Examiner(s): Parikh; Kalpit
• Application Number:
  US11/829,819
• Publication Number:
  US 20090027799A1
• Time in Patent Office: 1,390 Days
• Field of Search: 711/112
• US Class Current: 711/112
• 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 including a first refresh zone and a second refresh zone, wherein;

the first refresh zone comprises a plurality of tracks including a first track;

the second refresh zone comprises a plurality of tracks including a second track; and

a data rate of the second track is greater than a data rate of the first track;

a head actuated over the disk; and

control circuitry operable to;

receive access commands from a host;

refresh the first refresh zone in a first plurality of segments having a first segment size, wherein the first plurality of segments are refreshed with a first interval between each segment;

refresh the second refresh zone in a second plurality of segments having a second segment size, wherein the second plurality of segments are refreshed with a second interval between each segment; and

process at least one of the access commands during the first and second intervals;

wherein the first segment size is different from the second segment size.

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

the first track comprises a first number of data sectors; and

the first segment size is based on the first number of data sectors.

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

the first track comprises a plurality first number of data sectors;

a first number of skew data sectors is associated with a contiguous access pattern when switching tracks within the first refresh zone; and

the first segment size is based on the first number of skew data sectors.

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

the first track comprises a first number of data sectors;

a first number of skew data sectors is associated with a contiguous access pattern when switching tracks within the first refresh zone; and

the first segment size is based on the first number of data sectors per track and the first number of skew data sectors.

5. 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 each segment; and

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

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

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

7. The disk drive as recited in claim 5, 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 second threshold.

8. The disk drive as recited in claim 1, wherein the control circuitry is further operable to adjust at least one of the first and second intervals.

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

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

adjust at least one of the first and second intervals based on a number of access commands in the command queue.

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

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

adjust at least one of the first and second intervals based on a number of refresh zones in the refresh queue.

11. A method of operating a disk drive, the disk drive comprising a head actuated over a disk, the disk comprising a plurality of refresh zones including a first refresh zone and a second refresh zone, wherein:

the first refresh zone comprises a plurality of tracks including a first track;

the second refresh zone comprises a plurality of tracks including a second track; and

a data rate of the second track is greater than a data rate of the first track;

the method comprising;

receiving access commands from a host;

refreshing the first refresh zone in a first plurality of segments having a first segment size, wherein the first plurality of segments are refreshed with a first interval between each segment;

refreshing the second refresh zone in a second plurality of segments having a second segment size, wherein the second plurality of segments are refreshed with a second interval between each segment; and

processing at least one of the access commands during the first and second intervals;

wherein the first segment size is different from the second segment size.

12. The method as recited in claim 11, wherein:

the first track comprises a first number of data sectors; and

the first segment size is based on the first number of data sectors.

13. The method as recited in claim 11, wherein:

the first track comprises a first number of data sectors;

a first number of skew data sectors is associated with a contiguous access pattern when switching tracks within the first refresh zone; and

the first segment size is based on the first number of skew data sectors.

14. The method as recited in claim 11, wherein:

the first track comprises a first number of data sectors;

a first number of skew data sectors is associated with a contiguous access pattern when switching tracks within the first refresh zone; and

the first segment size is based on the first number of data sectors per track and the first number of skew data sectors.

15. The method as recited in claim 11, further comprising:

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

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

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

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

17. The method as recited in claim 15, 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.

18. The method as recited in claim 11, further comprising adjusting at least one of the first and second intervals.

19. The method as recited in claim 18, further comprising

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

and

adjusting at least one of the first and second intervals based on a number of access commands in the command queue.

20. The method as recited in claim 18, further comprising:

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

adjusting at least one of the first and second intervals based on a number of refresh zones in the refresh queue.

21. A disk drive as comprising:

a disk comprising a plurality of refresh zones including a first refresh zone and a second refresh zone, wherein;

the first refresh zone comprises a plurality of tracks including a first track;

the second refresh zone comprises a plurality of tracks including a second track; and

a data rate of the second track is greater than a data rate of the first track;

a head actuated over the disk;

a means for receiving access commands from a host;

a means for refreshing the first refresh zone in a first plurality of segments having a first segment size, wherein the first plurality of segments are refreshed with a first interval between each segment;

a means for refreshing the second refresh zone in a second plurality of segments having a second segment size, wherein the second plurality of segments are refreshed with a second interval between each segment;

a means for processing at least one of the access commands during the first and second intervals; and

wherein the first segment size is different from the second segment size.