Data storage device comprising extended servo burst field over part of a disk surface
A data storage device is disclosed comprising a head actuated over a disk surface comprising a plurality of servo sectors, wherein each servo sector comprises a servo burst field. Across a first radial band of servo tracks, the servo burst field comprises a first length, and across a second radial band of servo tracks, the servo burst field comprises a second length longer than the first length. When the head is over the first radial band of the servo tracks, the head is servoed over the disk surface based on the first read element reading a first servo sector and the second read element concurrently reading a second servo sector different from the first servo sector. When the head is over the second radial band of the servo tracks, the head is servoed over the disk surface based on the first read element reading a third servo sector.
1. A data storage device comprising:
a disk surface comprising a plurality of servo tracks defined by servo sectors, wherein:
each servo sector comprises a servo burst field; and
across a first radial band of the servo tracks, the servo burst field comprises a first length; and
across a second radial band of the servo tracks, the servo burst field comprises a second length longer than the first length;
a head actuated over the disk surface, wherein the head comprises a first read element and a second read element offset radially from the first read element when the head is over the first radial band of the servo tracks; and
control circuitry configured to:
when the head is over the first radial band of the servo tracks, servo the head over the disk surface based on the first read element reading a first servo sector and the second read element concurrently reading a second servo sector different from the first servo sector; and
when the head is over the second radial band of the servo tracks, servo the head over the disk surface based on the first read element reading a third servo sector.
2. The data storage device as recited in claim 1 , wherein when the head is over the second radial band of the servo tracks, the control circuitry is further configured to servo the head over the disk surface based on the second read element reading the third servo sector.
3. The data storage device as recited in claim 1 , wherein:
across the first radial band, the servo burst field comprises a first servo burst having a first burst length; and
across the second radial band, the servo burst field comprises a second servo burst having a second burst length longer than the first burst length.
4. The data storage device as recited in claim 1 , wherein:
across the first radial band, the servo burst field comprises a single set of servo bursts configured to generate a position error signal (PES) representing a position of the head relative to a servo track; and
across the second radial band, the servo burst field comprises multiple sets of servo bursts each configured to generate a PES of the head.
5. The data storage device as recited in claim 4 , wherein the control circuitry is further configured to overwrite at least part of the servo burst field with user data across at least part of the first radial band, thereby truncating the servo burst field to the first length.
6. The data storage device as recited in claim 5 , wherein the control circuitry is further configured to overwrite a second set of servo bursts within the servo burst field across the first radial band, thereby leaving the servo burst field with the single set of servo bursts.
7. The data storage device as recited in claim 1 , wherein:
the first radial band comprises at least one of an outer diameter band of the servo tracks and an inner diameter band of the servo tracks; and
the second radial band consists of a middle diameter band of the servo tracks.
8. The data storage device as recited in claim 1 , wherein:
the first radial band comprises at least one of an outer diameter band of the servo tracks and an inner diameter band of the servo tracks; and
the second radial band consists of one of an outer diameter band of the servo tracks and an inner diameter band of the servo tracks.
9. A method of operating a data storage device, the method comprising:
when a head is over a first radial band of servo tracks, servoing the head over a disk surface based on a first read element reading a first servo sector and a second read element concurrently reading a second servo sector different from the first servo sector; and
when the head is over a second radial band of servo tracks, servoing the head over the disk surface based on the first read element reading a third servo sector, wherein:
the disk surface comprises a plurality of servo tracks defined by servo sectors including the first and second radial bands of servo tracks, wherein:
each servo sector comprises a servo burst field; and
across the first radial band of the servo tracks, the servo burst field comprises a first length; and
across the second radial band of the servo tracks, the servo burst field comprises a second length longer than the first length; and
the head comprises the first read element and the second read element offset radially from the first read element when the head is over the first radial band of the servo tracks.
10. The method as recited in claim 9 , wherein when the head is over the second radial band of the servo tracks, the method further comprises servoing the head over the disk surface based on the second read element reading the third servo sector.
11. The method as recited in claim 9 , wherein:
across the first radial band, the servo burst field comprises a first servo burst having a first burst length; and
across the second radial band, the servo burst field comprises a second servo burst having a second burst length longer than the first burst length.
12. The method as recited in claim 9 , wherein:
across the first radial band, the servo burst field comprises a single set of servo bursts configured to generate a position error signal (PES) representing a position of the head relative to a servo track; and
across the second radial band, the servo burst field comprises multiple sets of servo bursts each configured to generate a PES of the head.
13. The method as recited in claim 12 , further comprising overwriting at least part of the servo burst field with user data across at least part of the first radial band, thereby truncating the servo burst field to the first length.
14. The method as recited in claim 13 , further comprising overwriting a second set of servo bursts within the servo burst field across the first radial band, thereby leaving the servo burst field with the single set of servo bursts.
15. The method as recited in claim 9 , wherein:
the first radial band comprises at least one of an outer diameter band of the servo tracks and an inner diameter band of the servo tracks; and
the second radial band consists of a middle diameter band of the servo tracks.
16. The method as recited in claim 9 , wherein:
the first radial band comprises at least one of an outer diameter band of the servo tracks and an inner diameter band of the servo tracks; and
the second radial band consists of one of an outer diameter band of the servo tracks and an inner diameter band of the servo tracks.
17. Control circuitry for use in a data storage device, the control circuitry configured to:
when a head is over a first radial band of servo tracks, servo the head over a disk surface based on a first read element reading a first servo sector and a second read element concurrently reading a second servo sector different from the first servo sector; and
when the head is over a second radial band of servo tracks, servo the head over the disk surface based on the first read element reading a third servo sector, wherein:
the disk surface comprises a plurality of servo tracks defined by servo sectors including the first and second radial bands of servo tracks, wherein:
each servo sector comprises a servo burst field; and
across the first radial band of the servo tracks, the servo burst field comprises a first length; and
across the second radial band of the servo tracks, the servo burst field comprises a second length longer than the first length; and
the head comprises the first read element and the second read element offset radially from the first read element when the head is over the first radial band of the servo tracks.
18. The control circuitry as recited in claim 17 , wherein:
across the first radial band, the servo burst field comprises a single set of servo bursts configured to generate a position error signal (PES) representing a position of the head relative to a servo track; and
across the second radial band, the servo burst field comprises multiple sets of servo bursts each configured to generate a PES of the head.
19. The control circuitry as recited in claim 18 , wherein the control circuitry is further configured to overwrite at least part of the servo burst field with user data across at least part of the first radial band, thereby truncating the servo burst field to the first length.
20. The control circuitry as recited in claim 19 , wherein the control circuitry is further configured to overwrite a second set of servo bursts within the servo burst field across the first radial band, thereby leaving the servo burst field with the single set of servo bursts.