Write encroachment mitigation system
The disclosed technology provides for a method and system comprising determining a write-encroachment threshold of a recording medium, determining a track as off-track and one or more tracks substantially near the off-track as unwriteable, flagging the one or more tracks substantially near the off-track track, and writing write data for the one or more flagged tracks to a media cache. In a recovery process, the write data can be later transferred back to the flagged tracks.
1. A method comprising:
determining a write-encroachment threshold (WET) of a recording medium;
determining a track as off-track and one or more tracks substantially near the off-track as unwriteable;
flagging the one or more tracks substantially near the off-track track; and
writing write data for the one or more flagged tracks to a media cache.
2. The method of claim 1 , wherein determining a WET of a recording medium as a percentage of cross-track width of tracks in the recording medium.
3. The method of claim 1 , wherein determining a track as off-track and one or more tracks substantially near the off-track as unwriteable is based on a position error signal level for the track exceeding the WET.
4. The method of claim 1 , further comprising transferring the write data from the media cache back to the flagged tracks when the media cache is full.
5. The method of claim 1 , wherein transferring the data from the media cache back to the flagged tracks further comprises reading all the data from the media cache and then writing the data from the media cache sequentially.
6. The method of claim 5 , further comprising clearing flags on the flagged tracks after the transferring operation.
7. The method of claim 1 , wherein the flagged tracks are adjacent to the off-track in the direction of the outer diameter of the recording medium.
8. The method of claim 1 , wherein the flagged tracks are adjacent to the off-track in the direction of the inner diameter of the recording medium.
9. The method of claim 1 , wherein the flagged tracks are adjacent to the off-track in the direction of the inner diameter and adjacent to the off-track in the direction of the inner diameter of the recording medium.
10. A storage device system, comprising:
a memory configured to store data on data tracks; and
a processor configured to determine a write-encroachment threshold (WET) of a recording, determine a track as off-track and one or more tracks substantially near the off-track as unwriteable, flag the one or more tracks substantially near the off-track track, and write write data for the one or more flagged tracks to a media cache.
11. The storage device of claim 10 , wherein determining a WET of a recording medium as a percentage of cross-track width of tracks in the recording medium.
12. The storage device of claim 10 , wherein determining a track as off-track and one or more tracks substantially near the off-track as unwriteable based on a position error signal level for the track exceeding the WET.
13. The storage device of claim 10 , wherein the processor is further configured to write requests to the media cache when a write request is made to the flagged tracks.
14. The storage device of claim 13 , wherein the processor is further configured to transfer the data from the media cache to the flagged tracks when the media cache is full.
15. The storage device of claim 14 , wherein the processor is further configured to read data from the media cache and then write the data from the flagged tracks from the media cache sequentially.
16. The storage device of claim 15 , wherein the processor is further configured to clear flags on the flagged data tracks when the data is written on the flagged tracks.
17. A method comprising:
determining a write-encroachment threshold (WET) of a recording medium;
determining a track as off-track and one or more tracks substantially near the off-track as unwriteable;
flagging the one or more tracks substantially near the off-track track;
writing write data for the one or more flagged tracks to a media cache; and
determining a +WET and a −WET and determining off-track tracks exceeding the +WET and the −WET.
18. The method of claim 17 , further comprising determining a write-encroachment threshold (WET) of a recording medium as a percentage of cross-track width of tracks in the recording medium and determining a track as off-track and one or more tracks substantially near the off-track as unwriteable is based on a position error signal level for the track exceeding the WET.
19. The method of claim 17 , further comprising re-reading data for the off-track track from a main storage and reading data for the one or more unwriteable tracks from the media cache if the +WET is exceeded, and writing the data from the off-track track and one or more unwriteable tracks sequentially.
20. The method of claim 17 , further comprising transferring data from the media cache back to the flagged tracks if −WET is exceeded and the cache is full.