Write head offset for shingled magnetic recording (SMR) disk drives

1. A method for data storage, comprising:

determining a write status of an adjacent track that is adjacent to a target track of a shingled magnetic recording (SMR) disk drive;

based on the write status of the adjacent track, shifting a write center of a write head by an offset to an unshingled side of the target track to increase an on-cylinder limit (OCLIM).

2. The method of claim 1 , wherein determining the write status of the adjacent track further comprises:

determining the write status of the adjacent track from a track usage monitoring (TUM) table.

3. The method of claim 1 , wherein shifting the write center of the write head further comprises:

shifting the write head according to the offset towards the adjacent track when the write status indicates the adjacent track is unused.

4. The method of claim 1 , further comprising:

determining a track overlap between the adjacent track and the target track; and

determining the offset based at least in part on the track overlap.

5. The method of claim 4 , further comprising:

determining the offset using half of a sum of the track overlap and two times an unadjusted on-cylinder limit (OCLIM).

6. The method of claim 1 , wherein shifting the write center of the write head further comprises:

positioning the write head by adding the offset to an unadjusted on-cylinder limit (OCLIM).

7. The method of claim 1 , wherein the offset amount is up to an amount that is a maximum on-cylinder limit (OCLIM).

8. The method of claim 1 , wherein the offset is equal to or less than an unadjusted on-cylinder limit (OCLIM).

9. The method of claim 1 , wherein determining the offset further comprises:

setting the offset to zero when the adjacent track is on a shingled side of the target track.

10. The method of claim 1 , further comprising:

receiving a write command to write data to the target track;

writing to the target track using the write head positioned according to the offset; and

updating a track usage monitoring (TUM) table based on the writing to the target track.

11. An apparatus, comprising:

at least one processor; and

memory coupled to the at least one processor, wherein the memory includes instructions that are executable by the at least one processor to:

determine a write status of an adjacent track that is adjacent to a target track of at least one data storage medium;

based on the write status of the adjacent track, shift a write center of a write head by an offset to an unshingled side of the target track to increase an on-cylinder limit (OCLIM).

12. The apparatus of claim 11 , wherein the memory further includes instructions that are executable by the at least one processor to determine the write status of the adjacent track from a track usage monitoring (TUM) table.

13. The apparatus of claim 11 , wherein the memory further includes instructions that are executable by the at least one processor to:

shift the write head according to the offset towards the adjacent track when the write status indicates the adjacent track is unused.

14. The apparatus of claim 11 , wherein the memory further includes instructions that are executable by the at least one processor to:

determine a track overlap between the adjacent track and the target track, further comprising determining the offset based at least in part on the track overlap.

15. The apparatus of claim 11 , wherein shifting the write center of the write head by an offset further comprises:

position the write head by adding the offset to an unadjusted on-cylinder limit (OCLIM).

16. The apparatus of claim 11 , wherein the memory further includes instructions that are executable by the at least one processor to:

receive a write command to write data to the target track;

write to the target track using the write head positioned according to the offset; and

update a track usage monitoring (TUM) table based on the writing to the target track.

17. A system, comprising:

at least one data storage medium to store data in a shingled manner;

a write head to write data to the data storage medium;

a read head to read data from the data storage medium;

at least one processor; and

memory coupled to the at least one processor, wherein the memory includes instructions that are executable by the at least one processor to:

determine a write status of an adjacent track that is adjacent to a target track of the at least one data storage medium;

based on the write status of the adjacent track, shift a write center of the write head by an offset to align the write head with the read head.

18. The system of claim 17 , further comprising:

a memory device to store a track usage monitoring (TUM) table that includes a write status for each track of the at least one data storage medium,

wherein the memory further includes instructions that are executable by the at least one processor to determine the write status of the adjacent track from the TUM table.

19. The system of claim 17 , wherein the memory further includes instructions that are executable by the at least one processor to:

shift the write head according to the offset towards the adjacent track when the write status indicates the adjacent track is unused.

20. The system of claim 17 , wherein the memory further includes instructions that are executable by the at least one processor to:

determine a track overlap between the adjacent track and the target track; and

determine the offset based at least in part on the track overlap.