Method and apparatus for determining a location of a defect on a storage medium

• US 7,995,301 B2
• Filed: 01/08/2010
• Issued: 08/09/2011
• Est. Priority Date: 01/14/2009
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Oberg, Mats
• Primary Examiner(s): Tzeng, Fred
• Application Number:
  US12/684,659
• Publication Number:
  US 20100177428A1
• Time in Patent Office: 578 Days
• Field of Search: 360/69, 360/53, 360/60, 360/77.06, 360/78.05, 360/78.06, 360/75, 360/264.5, 369/44.29, 369/274.1
• US Class Current: 360/69
• CPC Class Codes: G11B 20/1883 Methods for assignment of alternate areas for defective areas
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 7/0948 specially adapted for detection and avoidance or compensation of imperfections on the carrier, e.g. dust, scratches, dropouts G11B7/095 takes precedence

Abstract

A defect is detected on a storage medium of a disk drive. A location of the defect is determined, within a smallest addressable unit of data stored on the storage medium. An indication of the location is stored in a memory. A location of a sensor of the disk drive relative to the data stored on the storage medium is monitored. A response of at least one of a defect detector of the disk drive, a read channel controller of the disk drive, and a servo controller of the disk drive is changed based on the location of the sensor relative to the data stored on the storage medium and the stored indication of the location of the defect.

Claims

1. A method, comprising:

detecting a defect on a storage medium of a disk drive;

determining, within a smallest addressable unit of data stored on the storage medium, a location of the defect;

storing an indication of the location in a memory;

monitoring a location of a sensor of the disk drive relative to the data stored on the storage medium; and

changing a response of at least one of a defect detector of the disk drive, a read channel controller of the disk drive, and a servo controller of the disk drive based on the location of the sensor relative to the data stored on the storage medium and the stored indication of the location of the defect.

2. A method according to claim 1, wherein the location of the defect is on a first track of the storage medium, wherein the method further comprises predicting a second location of the defect on a second track of the storage medium based on the stored indication of the location of the defect, and wherein changing the response of the at least one of the defect detector, the read channel controller, and the servo controller comprises changing the response when the sensor is at the second location on the second track.

3. A method according to claim 1, wherein the location of the defect is on a first track of the storage medium, and wherein the method further comprises:

determining a second location of the defect on a second track of the storage medium; and

predicting a third location of the defect on a third track of the storage medium based on the stored indication of the location of the defect and the second location.

4. A method according to claim 1, wherein changing the response of the read channel controller to the defect comprises increasing a gain applied to a read signal.

5. A method according to claim 4, wherein increasing the gain comprises increasing the gain in response to determining that an amplitude of data stored on the storage medium at the location of the defect is above a threshold.

6. An apparatus, comprising:

a counter configured to generate counts associated with different locations on a storage medium of a disk drive;

a defect detector configured to detect defects on the storage medium; and

a defect boundary controller configured to;

determine a count of the counter corresponding to a location of a defect; and

change a response of at least one of the defect detector, a read channel controller of the disk drive, and a servo controller of the disk drive based on the count and the counter.

7. An apparatus according to claim 6, further comprising a counter reset module configured to reset the counter at one or more counter reset locations;

wherein the defect boundary controller is configured to;

determine a particular counter reset location corresponding to the defect; and

change the response of the at least one of the defect detector, the read channel controller, and the servo controller further based on the counter reset location corresponding to the defect.

8. An apparatus according to claim 7, wherein the count indicates a number of periods of a channel clock of the storage medium between the counter reset location corresponding to the defect and the defect location.

9. An apparatus according to claim 7, wherein the defect boundary controller is configured to cause the read channel controller to enter a defect mode when, after the counter is reset at the counter reset location, the counter reaches an adjusted count corresponding to the location of the defect.

10. An apparatus according to claim 7, wherein the defect boundary controller is configured to change a defect detection sensitivity of the defect detector when, after the counter is reset at the counter reset location, the counter indicates proximity to the defect.

11. An apparatus according to claim 7, wherein the location of the defect is on a first track of the storage medium, and wherein the defect boundary controller is configured to:

compute a compensation value based on the location of the defect; and

add the compensation value to the count corresponding to the location of the defect to predict a second location of the defect on a second track of the storage medium.

12. A method, comprising:

running a counter, wherein counts of the counter are associated with different locations on a storage medium of a disk drive;

detecting a defect on the storage medium using a defect detector;

determining a count of the counter corresponding to a location of the defect; and

changing a response of at least one of the defect detector, a read channel controller of the disk drive, and a servo controller of the disk drive based on the count and the counter.

13. A method according to claim 12, further comprising:

resetting the counter at one or more counter reset locations; and

determining a counter reset location corresponding to the defect;

wherein changing the response of the at least one of the defect detector, the read channel controller, and the servo controller is further based on the counter reset location corresponding to the defect.

14. A method according to claim 13, wherein the count indicates a number of periods of a channel clock of the storage medium occurring between the counter reset location corresponding to the defect and the defect location.

15. A method according to claim 13, wherein the counter reset location corresponding to the defect is a boundary of an error correction coding block on the storage medium.

16. A method according to claim 13, wherein the counter reset location corresponding to the defect is a boundary of a data sector on the storage medium.

17. A method according to claim 13, wherein the counter reset location corresponding to the defect is a predetermined angular position on the storage medium.

18. A method according to claim 12, wherein changing the response of the defect detector comprises changing a defect detection sensitivity of the defect detector when, after the counter is reset at the counter reset location, the counter indicates proximity to the defect.

19. A method according to claim 12, wherein changing the response of the read channel controller comprises causing the read channel controller to enter a defect mode when, after the counter is reset at the counter reset location, the counter reaches an adjusted count corresponding to the location of the defect.

20. A method according to claim 12, wherein the location of the defect is on a first track of the storage medium, and wherein the method further comprises:

determining a count of the counter corresponding to a second location of the defect on a second track of the storage medium; and

changing a response of at least one of the defect detector, the read channel controller, and the servo controller based on the count corresponding to the second location of the defect on the second track.