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

1. A method for data storage, comprising:

receiving a write command to write user data to a shingled magnetic recording (SMR) disk drive;

selecting a target track on the SMR disk drive to store the user data; and

writing the user data to the target track using an adjusted or an unadjusted on-cylinder limit (OCLIM) based at least in part on a write status of an adjacent track that is adjacent to the target track.

2. The method of claim 1 , further comprising:

determining the write status of the adjacent track that is adjacent to the target track.

3. The method of claim 2 , 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.

4. The method of claim 2 , further comprising:

writing the user data to the target track with the unadjusted OCLIM when the write status indicates the adjacent track is used.

5. The method of claim 2 , further comprising:

determining an offset for a write head based on the write status of the adjacent track when the write status indicates the adjacent track is unused; and

adjusting a position of the write head according to the offset.

6. The method of claim 5 , further comprising:

determining a track overlap between the adjacent track and the target track, wherein determining the offset is based at least in part on the track overlap.

7. The method of claim 5 , wherein adjusting the position 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.

8. The method of claim 5 , wherein adjusting the position of the write head further comprises:

aligning the write head with a read head position for the target track.

9. The method of claim 5 , wherein adjusting the position of the write head further comprises:

positioning the write head by adding the offset to the unadjusted OCLIM.

10. The method of claim 5 , wherein positioning the write head further comprises:

shifting a write center of a write head by the offset to an unshingled side of the target track, wherein the offset is equal to or less than the unadjusted on-cylinder limit (OCLIM).

11. The method of claim 5 , wherein determining the offset further comprises:

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

12. The method of claim 5 , wherein determining the offset further comprises:

determining half of a sum of the track overlap and two times the OCLIM.

13. The method of claim 1 , wherein the adjacent track is on an unshingled side of the target track.

14. The method of claim 1 , further comprising:

updating a track usage monitoring (TUM) table upon writing the user data to the target track.

15. 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:

receive a write command to write user data to a shingled magnetic recording (SMR) disk drive;

select a target track on the SMR disk drive to store the user data;

determine a write status of an adjacent track that is adjacent to the target track; and

write the user data to the target track using an adjusted or an unadjusted on-cylinder limit (OCLIM) based at least in part on the write status of the adjacent track.

16. The apparatus of claim 15 , wherein the instructions to determine the write status of the adjacent track further includes instructions that are executable by the at least one processor to:

write the user data to the target track with the unadjusted OCLIM when the write status indicates the adjacent track is used.

17. The apparatus of claim 15 , wherein the memory further includes instructions that are executable by the at least one processor to:

determine an offset for a write head based on the write status of the adjacent track when the write status indicates the adjacent track is unused; and

adjust a position of the write head according to the offset.

18. The apparatus of claim 15 , 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, wherein determining the offset is based at least in part on the track overlap.

19. 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;

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:

receive a write command to write user data to a shingled magnetic recording (SMR) disk drive;

select a target track on the SMR disk drive to store the user data; and

write the user data to the target track using an adjusted or an unadjusted on-cylinder limit (OCLIM) based at least in part on a write status of an adjacent track that is adjacent to the target track.

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

write the user data to the target track with the unadjusted OCLIM when the write status indicates the adjacent track is used; and

determine an offset for a write head based on the write status of the adjacent track and adjust a position of the write head according to the offset when the write status indicates the adjacent track is unused.