Angular position tracking of data accesses to mitigate risk of data loss

• US 9,466,321 B1
• Filed: 06/05/2015
• Issued: 10/11/2016
• Est. Priority Date: 06/05/2015
• 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: Meertens, Marika, Vinson, Wayne H., Olds, Edwin S.
• Primary Examiner(s): Dinh, Tan X
• Application Number:
  US14/732,015
• Time in Patent Office: 494 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G11B 15/43 Control or regulation of mechanical tension of record carrier, e.g. tape tension
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D
• CPC Class Codes: G11B 5/59627 Aligning for runout, eccentricity or offset compensation G11B5/5534, G11B5/59677, G11B5/59688 take precedence

Abstract

Systems, apparatuses, and methods use angular position tracking in mitigating data loss risks stemming from adjacent track interference (ATI), wide area track erasure (WATER), and/or other issues. A storage device includes a rotational magnetic storage medium divided into a group of tracks and a controller communicably coupled to the rotational magnetic storage medium. The controller is configured to: determine, based on an angular position of a write operation within a group of tracks, whether the angular position of the write operation overlaps a previously written area in the group of tracks; in the event the angular position of the write operation overlaps the previously written area in the group of tracks, increment a counter; and in the event the counter exceeds a counter threshold, perform a data loss risk mitigation procedure.

Claims

1. A storage device, comprising:

a rotational magnetic storage medium divided into groups of tracks; and

a controller, communicably coupled to the rotational magnetic storage medium, the controller being configured to;

determine, based on an angular position of a write operation within a group of tracks, whether the angular position of the write operation overlaps a previously written area in the group of tracks;

in the event the angular position of the write operation overlaps the previously written area in the group of tracks, increment a counter; and

in the event the counter exceeds a counter threshold, perform a data loss risk mitigation procedure.

2. The storage device of claim 1, wherein:

the controller is further configured to determine whether the angular position of the write operation overlaps the previously written area in the group of tracks by determining whether the angular position of the write operation is below a maximum previous write location pointer for the group of tracks; and

the maximum previous write location pointer indicates a highest written servo wedge of a group of adjacent servo wedges.

3. The storage device of claim 2, wherein a resolution of the maximum previous write location pointer corresponds to space available in volatile memory of the storage device while the storage device is in operation.

4. The storage device of claim 1, wherein:

the controller is further configured to determine whether the angular position of the write operation overlaps the previously written area in the group of tracks by determining whether the angular position of the write operation is between a minimum previous write location pointer and a maximum previous write location pointer for the group of tracks; and

the maximum and minimum previous write location pointers indicate an area of previous write angular positions in a group of adjacent servo wedges.

5. The storage device of claim 1, wherein the controller is further configured to determine whether the angular position of the write operation overlaps the previously written area in the group of tracks by comparing the angular position of the write operation to a bit mask that represents indications of previous write angular positions in a group of adjacent servo wedges.

6. The storage device of claim 5, wherein a resolution of the bit mask corresponds to space available in volatile memory of the storage device while the storage device is in operation.

7. The storage device of claim 1, wherein the controller is further configured to determine the angular position of the write operation by performing a logical to physical address translation.

8. The storage device of claim 1, wherein:

the controller is further configured to determine whether the angular position of the write operation overlaps the previously written area in the group of tracks by determining whether the angular position of the write operation is above a minimum previous write location pointer for the group of tracks; and

the minimum previous write location pointer indicates a lowest written servo wedge of a group of adjacent servo wedges.

9. The storage device of claim 1, wherein the data loss risk mitigation procedure comprises:

reading data of the group of tracks; and

in the event that an error correcting code correction of the reading is above an error correction threshold, rewriting the read data to the group of tracks.

10. A method for determining when to perform a data loss risk mitigation procedure, the method comprising:

comparing, utilizing an electronic device, an angular position of a current write to at least one pointer indicating an area of a group of tracks of a rotational magnetic storage medium where at least one write has been performed subsequent to incrementing a counter;

in the event the comparison indicates the angular position overlaps the area, incrementing the counter utilizing the electronic device; and

in the event the counter exceeds a threshold, performing a data loss risk mitigation procedure utilizing the electronic device.

11. The method of claim 10, further comprising:

in the event the comparison indicates the angular position does not overlap the area, updating the at least one pointer in accordance with the current write.

12. The method of claim 10, wherein the at least one pointer comprises a first pointer representing a lower boundary of previous write angular positions in a group of adjacent servo wedges and a second pointer representing an upper boundary of the previous write angular positions in the group of adjacent servo wedges.

13. The method of claim 12, further comprising:

in the event the comparison indicates the angular position overlaps the area, resetting the first pointer and the second pointer to indicate the current write.

14. The method of claim 10, wherein said operation of comparing the angular position of the current write to the at least one pointer further comprises determining whether the angular position is between a maximum previous write location pointer indicating a highest written servo wedge of a group of adjacent servo wedges and a zero index for the group of adjacent servo wedges.

15. The method of claim 10, wherein a resolution of the at least one pointer corresponds to space available in volatile memory for tracking performed writes during operation of the rotational magnetic storage medium.

16. The method of claim 10, further comprising performing logical to physical address translation to obtain the angular position.

17. The method of claim 10, wherein the data loss risk mitigation procedure comprises:

reading data of the group of tracks; and

in the event that an error correcting code correction of the reading is above an error correction threshold, rewriting the read data to the group of tracks.

18. A method for determining when to perform a data loss risk mitigation procedure, the method comprising:

comparing, utilizing an electronic device, an angular position of a current write to a bit mask including data indicating areas of a group of tracks of a rotational magnetic storage medium where writes have been performed subsequent to incrementing a counter;

in the event the bit mask indicates the angular position overlaps the areas, incrementing the counter utilizing the electronic device; and

in the event the counter exceeds a threshold, performing a data loss risk mitigation procedure utilizing the electronic device.

19. The method of claim 18, wherein the bit mask includes a location storing information corresponding to the angular position.

20. The method of claim 18, wherein the data included in the bit mask indicates all areas of the group of tracks where writes have been performed subsequent to incrementing the counter.

21. The method of claim 18, further comprising at least one of:

in the event the bit mask indicates the angular position does not overlap the areas, updating the bit mask in accordance with the current write;

or

in the event the bit mask indicates the angular position overlaps the areas, resetting the data of the bit mask and updating the bit mask in accordance with the current write.

22. The method of claim 18, wherein the data indicates previous write angular positions in a group of adjacent servo wedges.

23. The method of claim 18, wherein a resolution of the bit mask corresponds to space available in volatile memory for tracking performed writes during operation of the rotational magnetic storage medium.

24. The method of claim 18, further comprising:

comparing the angular position to an additional bit mask indicating areas of an additional group of tracks where writes have been performed subsequent to incrementing an additional counter;

in the event the additional bit mask indicates the angular position overlaps the areas of the additional group of tracks, incrementing the additional counter; and

in the event the additional counter exceeds the threshold, performing the data loss risk mitigation procedure.

25. The method of claim 18, wherein the bit mask is associated with adjacent track interference in the group of tracks, further comprising:

comparing the angular position to an additional bit mask associated with wide area track erasure in the group of tracks;

in the event the additional bit mask indicates the angular position overlaps a previously written area, incrementing an additional counter; and

in the event the additional counter exceeds the threshold, performing the data loss risk mitigation procedure.

26. The method of claim 18, wherein the data loss risk mitigation procedure comprises:

reading data of the group of tracks; and

in the event that an error correcting code correction of the reading is above an error correction threshold, rewriting the read data to the group of tracks.