Disk defect management for a data storage device

• US 9,361,938 B1
• Filed: 06/12/2015
• Issued: 06/07/2016
• Est. Priority Date: 04/16/2015
• 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: Selvaraj, Gomez S.
• Primary Examiner(s): Hindi, Nabil
• Application Number:
  US14/737,822
• Time in Patent Office: 361 Days
• Field of Search: 360/31, 360/40, 360/48, 360/53, 369/53.1, 369/53.14, 369/53.15, 369/53.17, 369/53.21, 369/53.12, 369/53.24
• US Class Current: 1/1
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 20/1889 with discs

Abstract

A Data Storage Device (DSD) includes at least one disk surface for storing data and a memory for storing a bitmap buffer. A segment of a disk surface is identified that includes at least one defect region, and a segment bitmap is generated for the segment indicating the at least one defect region within the segment. The segment bitmap is stored in the bitmap buffer.

Claims

1. A Data Storage Device (DSD), comprising:

at least one disk surface for storing data;

a memory for storing a bitmap buffer; and

a controller configured to;

identify a plurality of segments on the at least one disk surface with each segment including at least one defect region;

generate a segment bitmap for each of the plurality of segments indicating the at least one defect region within the segment;

store the generated segment bitmaps for the plurality of segments in the bitmap buffer; and

create a linked list with a plurality of entries corresponding to the plurality of segments, wherein each entry of the plurality of entries includes location information for a segment of the plurality of segments indicating a location of the segment on the at least one disk surface and an address for accessing a segment bitmap for the segment in the bitmap buffer.

2. The DSD of claim 1, wherein the controller is further configured to:

identify a new defect region during operation of the DSD;

determine whether the new defect region is within an existing segment of the plurality of segments; and

if the new defect region is within the existing segment, update the segment bitmap for the existing segment to indicate the new defect region within the existing segment.

3. The DSD of claim 1, wherein the controller is further configured to:

identify a new defect region during operation of the DSD;

determine whether the new defect region is within or adjacent to an existing segment of the plurality of segments on the at least one disk surface; and

if the new defect region is not within or adjacent to an existing segment of the plurality of segments;

identify a new segment including the new defect region;

generate a new segment bitmap indicating the new defect region within the new segment;

store the new segment bitmap in the bitmap buffer; and

create a new entry in the linked list for the new segment including location information for the new segment indicating a location of the new segment on the at least one disk surface and an address for accessing the new segment bitmap in the bitmap buffer.

4. The DSD of claim 1, wherein the controller is further configured to:

identify a new defect region during operation of the DSD;

determine whether the new defect region is adjacent to an existing segment of the plurality of segments on the at least one disk surface; and

if the new defect region is adjacent to an existing segment;

expand a segment bitmap for the existing segment to indicate the new defect region; and

update an existing entry in the linked list for the existing segment so that the location information for the existing segment indicates a location on the at least one disk surface that includes the new defect region.

5. The DSD of claim 1, wherein the controller is further configured to:

identify a new defect region during operation of the DSD; and

use the linked list to determine whether the new defect region is within or adjacent to an existing segment of the plurality of segments.

6. The DSD of claim 1, wherein the at least one disk surface includes a plurality of disk surfaces that are circumferentially aligned with each other, and wherein the controller is further configured to use the linked list to identify segments of the plurality of segments that are on different disk surfaces of the plurality of disk surfaces and are located at the same radial or circumferential location.

7. The DSD of claim 1, wherein the controller is further configured to use the linked list to identify a defect pattern on a disk surface of the plurality of disk surfaces.

8. The DSD of claim 1, wherein the controller is further configured to determine a defect status for a portion of the at least one disk surface by searching the linked list for an entry corresponding to a matching segment including the portion of the at least one disk surface.

9. The DSD of claim 8, wherein if an entry corresponding to the matching segment is found in the linked list, the controller is further configured to read a corresponding segment bitmap for the matching segment in the bitmap buffer to determine the defect status for the portion of the at least one disk surface.

10. The DSD of claim 1, wherein the at least one disk surface includes a plurality of tracks for storing data in sectors in each track of the plurality of tracks, and wherein the segment bitmap indicates whether each sector in the segment has a defect.

11. The DSD of claim 1, wherein the at least one disk surface includes a plurality of tracks for storing data and a plurality of servo wedges along the plurality of tracks to indicate a position on a disk surface of the at least one disk surface, and wherein the segment bitmap indicates whether a portion of a track between two servo wedges in the segment has a defect.

12. A method for operating a Data Storage Device (DSD) including at least one disk surface for storing data and a memory for storing a bitmap buffer, the method comprising:

identifying a plurality of segments on the at least one disk surface with each segment including at least one defect region;

generating a segment bitmap for each of the plurality of segments indicating the at least one defect region within the segment;

storing the generated segment bitmaps for the plurality of segments in the bitmap buffer; and

creating a linked list with a plurality of entries corresponding to the plurality of segments, wherein each entry of the plurality of entries includes location information for a segment of the plurality of segments indicating a location of the segment on the at least one disk surface and an address for accessing a segment bitmap for the segment in the bitmap buffer.

13. The method of claim 12, further comprising:

identifying a new defect region during operation of the DSD;

determining whether the new defect region is within an existing segment of the plurality of segments; and

if the new defect region is within the existing segment, updating the segment bitmap to indicate the new defect region within the existing segment.

14. The method of claim 12, further comprising:

identifying a new defect region during operation of the DSD;

determining whether the new defect region is within or adjacent to an existing segment of the plurality of segments on the at least one disk surface; and

if the new defect region is not within or adjacent to an existing segment of the plurality of segments;

identifying a new segment including the new defect region;

generating a new segment bitmap indicating the new defect region within the new segment;

storing the new segment bitmap in the bitmap buffer; and

creating a new entry in the linked list for the new segment including location information for the new segment indicating a location of the new segment on the at least one disk surface and an address for accessing the new segment bitmap in the bitmap buffer.

15. The method of claim 12, further comprising:

identifying a new defect region during operation of the DSD;

determining whether the new defect region is adjacent to an existing segment of the plurality of segments on the at least one disk surface; and

if the new defect region is adjacent to an existing segment;

expanding a segment bitmap for the existing segment to indicate the new defect region; and

updating an existing entry in the linked list for the existing segment so that the location information for the existing segment indicates a location on the at least one disk surface that includes the new defect region.

16. The method of claim 12, further comprising:

identifying a new defect region during operation of the DSD; and

using the linked list to determine whether the new defect region is within or adjacent to an existing segment of the plurality of segments.

17. The method of claim 12, wherein the at least one disk surface includes a plurality of disk surfaces that are circumferentially aligned with each other, and wherein the method further comprises using the linked list to identify segments of the plurality of segments that are on different disk surfaces of the plurality of disk surfaces and are located at the same radial or circumferential location.

18. The method of claim 12, further comprising using the linked list to identify a defect pattern on a disk surface of the plurality of disk surfaces.

19. The method of claim 12, further comprising determining a defect status for a portion of the at least one disk surface by searching the linked list for an entry corresponding to a matching segment including the portion of the at least one disk surface.

20. The method of claim 19, wherein if an entry corresponding to the matching segment is found in the linked list, the method further comprises reading a corresponding segment bitmap for the matching segment in the bitmap buffer to determine the defect status for the portion of the at least one disk surface.

21. The method of claim 12, wherein the at least one disk surface includes a plurality of tracks for storing data in sectors in each track of the plurality of tracks, and wherein the segment bitmap indicates whether each sector in the segment has a defect.

22. The method of claim 12, wherein the at least one disk surface includes a plurality of tracks for storing data and a plurality of servo wedges along the plurality of tracks to indicate a position on a disk surface of the at least one disk surface, and wherein the segment bitmap indicates whether a portion of a track between two servo wedges in the segment has a defect.

23. A non-transitory computer readable medium storing computer executable instructions for operating a Data Storage Device (DSD) including at least one disk surface for storing data and a memory for storing a bitmap buffer, wherein when the computer executable instructions are executed by a controller of the DSD, the computer executable instructions cause the controller to:

identify a plurality of segments on the at least one disk surface with each segment including at least one defect region;

generate a segment bitmap for each of the plurality of segments indicating the at least one defect region within the segment; and

store the generated segment bitmaps for the plurality of segments in the bitmap buffer; and

create a linked list with a plurality of entries corresponding to the plurality of segments, wherein each entry of the plurality of entries includes location information for a segment of the plurality of segments indicating a location of the segment on the at least one disk surface and an address for accessing a segment bitmap for the segment in the bitmap buffer.