Segmenting of read-modify-write operations

• US 8,879,183 B1
• Filed: 03/15/2013
• Issued: 11/04/2014
• Est. Priority Date: 10/11/2012
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Weikal, Adam
• Primary Examiner(s): HOLDER, REGINA NEAL
• Application Number:
  US13/832,178
• Time in Patent Office: 599 Days
• Field of Search: None
• US Class Current: 360/48
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 9/3004 to perform operations on memory
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/1277 for managing gaps between two recordings, e.g. control data in linking areas, run-in or run-out fields, guard or buffer zones
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/09 Digital recording

Abstract

Systems, devices, apparatuses, and methods for segmented read-modify-write operations are disclosed. The examples provided can allow a system to perform a read-modify-write (RMW) operation for data stored in a main storage that has a larger data size than is capable of being stored in an available buffer. Examples of such a system include discs having bands of shingled tracks. In such example, each band can be split into segments containing one or more tracks and a read-modify-write-write (RMWW) operation can be performed for each segment. Further, a logical guard band can be implemented to protect the segments from overwriting a next track in a shingled band. Also, multiple scratchpads may be implemented.

Claims

1. An apparatus comprising:

a data storage medium including a band of tracks having multiple data tracks arranged in a shingled manner where at least one track partially overlaps an adjacent track;

a controller configured to;

virtually divide the band of tracks into at least a first segment and a second segment, each segment containing at least one track;

perform a first read-modify-write-write operation for the first segment; and

perform a second read-modify-write-write operation for the second segment.

2. The apparatus of claim 1, comprising:

the controller further configured to;

read the first segment into a buffer;

modify data of the first segment in the buffer;

write the modified data of the first segment to a first scratchpad; and

write a portion of the modified data of the first segment that is less than all of the first segment to physically adjacent tracks corresponding to the first segment on the data storage medium.

3. The apparatus of claim 2, comprising:

the controller further configured to;

read the second segment into the buffer;

modify data of the second segment in the buffer;

write the modified data of the second segment including at least a last track of the first segment to a second scratchpad; and

write a portion of the modified data of the second segment that is less than all of the second segment to physically adjacent tracks corresponding to the second segment on the data storage medium.

4. The apparatus of claim 3, wherein the portion that is less than all of the first segment is the first segment minus a last adjacent track of the first segment.

5. The apparatus of claim 4, wherein the portion that is less than all of the second segment is the second segment minus a last adjacent track of the second segment.

6. The apparatus of claim 1, comprising:

the controller further configured to;

repeat performing a read-modify-write-write operation for any additional segments until all tracks within the band have gone through a corresponding read-modify-write-write operation; and

stop performing read-modify-write-write operations for the band when a last track in a segment is a physical guard band separating the band from other tracks not in the band.

7. The apparatus of claim 1, further comprising:

a first scratchpad;

a second scratchpad; and

the controller is further configured to write the first segment to the first scratchpad during the first read-modify-write-write operation and write the second segment to the second scratchpad during the second read-modify-write-write operation.

8. The apparatus of claim 7, comprising:

the controller is further configured to alternate between writing to the first scratchpad and the second scratchpad for further read-modify-write-write operations for additional segments of the band.

9. The apparatus of claim 1, further comprising:

the first segment includes a first range of physically adjacent tracks of the band;

the second segment includes a second range of physically adjacent tracks of the band; and

the first track of the second segment is adjacent to the last track of the first segment.

10. A method comprising:

dividing a shingled band of tracks of a data storage medium into at least a first segment and a second segment, each segment containing at least one track;

performing a first read-modify-write-write operation for the first segment; and

performing a second read-modify-write-write operation for the second segment.

11. The method of claim 10, further comprising the data storage medium includes multiple shingled bands of tracks having multiple overlapped data tracks arranged in a manner where at least one track partially overlaps an adjacent track.

12. The method of claim 10 further comprising implementing a logical guard band between the first read-modify-write-write operation and the second read-modify-write-write operation.

13. The method of claim 10 further comprising:

performing a read-modify-write-write (RMWW) operation for any additional segments until all tracks within the shingled band have gone through a corresponding read-modify-write-write operation; and

stop performing RMWW operations for the band when a last track in a segment is a physical guard band separating the shingled band from other tracks not in the band.

14. The method of claim 13 further comprising implementing a floating logical guard band between segments corresponding to two successive read-modify-write-write operations.

15. The method of claim 13 further comprising implementing a floating logical guard band and moving the floating logical guard band to between a segment last processed through a RMWW operation and a next segment to be processed through a RMWW operation.

16. The method of claim 10, further comprising:

writing the first segment to a first scratchpad during the first read-modify-write-write operation; and

writing the second segment to a second scratchpad during the second read-modify-write-write operation.

17. The method of claim 16, further comprising alternating writing to the first scratchpad and the second scratchpad for alternate iterations of additional read-modify-write-write operations corresponding to additional segments of the shingled band.

18. A controller adapted to:

divide a shingled band of tracks of a data storage medium into at least a first segment and a second segment, each segment containing at least one track;

perform a first read-modify-write-write operation for the first segment; and

perform a second read-modify-write-write operation for the second segment.

19. The controller of claim 18 further adapted to

implement a logical guard band between the first read-modify-write-write operation and the second read-modify-write-write operation, wherein the logical guard band is not a physical guard band after the second read-modify-write-write operation has completed.

20. The controller of claim 18 further adapted to

write the first segment to a first scratchpad during the first read-modify-write-write operation;

and

write the second segment to a second scratchpad during the second read-modify-write-write operation.