Data storage device calibrating fly height actuator for multiple heads during a revolution
A data storage device is disclosed comprising a first head actuated radially over a first disk surface, and a second head actuated radially over a second disk surface. A seek operation seeks the first head to a first fly height calibration track and seeks the second head to a second fly height calibration track. During a revolution of the first and second disk surfaces the first head is used to read the first fly height calibration track in order to calibrate a first fly height actuator for the first head, and after switching from the first head to the second head, the second head is used to read the second fly height calibration track in order to calibrate a second fly height actuator for the second head.
1. A data storage device comprising:
a first disk surface comprising a plurality of data tracks including a first fly height calibration track;
a first head actuated radially over the first disk surface;
a first fly height actuator configured to control a fly height of the first head over the first disk surface;
a second disk surface comprising a plurality of data tracks including a second fly height calibration track;
a second head actuated radially over the second disk surface;
a second fly height actuator configured to control a fly height of the second head over the second disk surface; and
control circuitry configured to:
seek the first head to the first fly height calibration track and seek the second head to the second fly height calibration track;
during a revolution of the first and second disk surfaces:
use the first head to read the first fly height calibration track in order to calibrate the first fly height actuator;
switch from the first head to the second head; and
use the second head to read the second fly height calibration track in order to calibrate the second fly height actuator.
2. The data storage device as recited in claim 1 , wherein using the first head to read the first fly height calibration track comprises:
using the first head to read a first calibration pattern from the first fly height calibration track in order to calibrate the first fly height actuator; and
using the first head to read a second calibration pattern form the first fly height calibration track in order to verify the calibration of the first fly height actuator.
3. The data storage device as recited in claim 2 , wherein:
the first calibration pattern comprises a repeating pattern of magnetic transitions; and
the second calibration pattern comprises a random pattern of magnetic transitions.
4. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to verify the calibration of the first fly height actuator by measuring a quality metric associated with reading the second calibration pattern.
5. The data storage device as recited in claim 4 , wherein the quality metric comprises an error rate associated with reading the second calibration pattern.
6. The data storage device as recited in claim 2 , wherein the first calibration pattern is interleaved with the second calibration pattern multiple times along the first fly height calibration track.
7. The data storage device as recited in claim 6 , wherein:
the first calibration pattern is interleaved with the second calibration pattern multiple times along the second fly height calibration track; and
the first and second calibration patterns on the second fly height calibration track are offset along the second fly height calibration track relative to the first and second calibration patterns on the first fly height calibration track.
8. The data storage device as recited in claim 7 , wherein the offset compensates for a settle interval after switching from the first head to the second head.
9. A data storage device comprising:
a first disk surface comprising a plurality of data tracks including a first fly height calibration track;
a first head actuated radially over the first disk surface;
a first fly height actuator configured to control a fly height of the first head over the first disk surface; and
control circuitry configured to:
seek the first head to the first fly height calibration track;
during a revolution of the first disk surface:
use the first head to read a first calibration pattern from the first fly height calibration track in order to calibrate the first fly height actuator; and
use the first head to read a second calibration pattern from the first fly height calibration track in order to verify the calibration of the first fly height actuator, wherein:
the first calibration pattern comprises a repeating pattern of magnetic transitions; and
the second calibration pattern comprises a random pattern of magnetic transitions.
10. The data storage device as recited in claim 9 , wherein the control circuitry is further configured to verify the calibration of the first fly height actuator by measuring a quality metric associated with reading the second calibration pattern.
11. The data storage device as recited in claim 10 , wherein the quality metric comprises an error rate associated with reading the second calibration pattern.
12. A data storage device comprising:
a first disk surface comprising a plurality of data tracks including a first fly height calibration track;
a first head actuated radially over the first disk surface;
a first fly height actuator configured to control a fly height of the first head over the first disk surface; and
control circuitry configured to:
seek the first head to the first fly height calibration track;
during a revolution of the first disk surface:
use the first head to read a first calibration pattern from the first fly height calibration track in order to calibrate the first fly height actuator; and
use the first head to read a second calibration pattern from the first fly height calibration track in order to verify the calibration of the first fly height actuator, wherein the first calibration pattern is interleaved with the second calibration pattern multiple times along the first fly height calibration track.
13. The data storage device as recited in claim 12 , further comprising:
a second disk surface comprising a plurality of data tracks including a second fly height calibration track;
a second head actuated radially over the second disk surface; and
a second fly height actuator configured to control a fly height of the second head over the second disk surface,
wherein during the revolution of the first disk surface the control circuitry is further configured to:
switch from the first head to the second head;
use the second head to read the first calibration pattern from the second fly height calibration track in order to calibrate the second fly height actuator; and
use the second head to read the second calibration pattern form the second fly height calibration track in order to verify the calibration of the second fly height actuator.
14. The data storage device as recited in claim 13 , wherein:
the first calibration pattern is interleaved with the second calibration pattern multiple times along the second fly height calibration track; and
the first and second calibration patterns on the second fly height calibration track are offset along the second fly height calibration track relative to the first and second calibration patterns on the first fly height calibration track.
15. The data storage device as recited in claim 14 , wherein the offset compensates for a settle interval after switching from the first head to the second head.
16. A data storage device comprising:
a first disk surface comprising a plurality of data tracks including a first fly height calibration track;
a first head actuated radially over the first disk surface;
a first fly height actuator configured to control a fly height of the first head over the first disk surface;
a second disk surface comprising a plurality of data tracks including a second fly height calibration track;
a second head actuated radially over the second disk surface;
a second fly height actuator configured to control a fly height of the second head over the second disk surface; and
a means for seeking the first head to the first fly height calibration track and seek the second head to the second fly height calibration track;
during a revolution of the first and second disk surfaces:
a means for using the first head to read the first fly height calibration track in order to calibrate the first fly height actuator;
a means for switching from the first head to the second head; and
a means for using the second head to read the second fly height calibration track in order to calibrate the second fly height actuator.
17. The data storage device as recited in claim 16 , wherein the means for using the first head to read the first fly height calibration track comprises:
a means for using the first head to read a first calibration pattern from the first fly height calibration track in order to calibrate the first fly height actuator; and
a means for using the first head to read a second calibration pattern form the first fly height calibration track in order to verify the calibration of the first fly height actuator.
18. The data storage device as recited in claim 17 , wherein:
the first calibration pattern comprises a repeating pattern of magnetic transitions; and
the second calibration pattern comprises a random pattern of magnetic transitions.
19. The data storage device as recited in claim 18 , further comprising a means for verifying the calibration of the first fly height actuator by measuring a quality metric associated with reading the second calibration pattern.