Disk drive employing different servo TPI to data TPI ratios across the disk surface

1. A disk drive comprising:

a first disk surface and a first head actuated over the first disk surface; and wherein:

the first disk surface comprises a plurality of servo tracks and a plurality of data tracks;

the data tracks of the first disk surface are banded together into a plurality of data zones, including a first data zone and a second data zone;

a first servo tracks per inch of the first data zone is different from a second servo tracks per inch of the second data zone; and

a first servo tracks per inch (STPI) to data tracks per inch (DTPI) ratio of the first data zone is substantially different from a second STPI to DTPI ratio of the second data zone.

2. The disk drive as recited in claim 1 , wherein the first STPI to DTPI ratio is constant across the first data zone.

3. The disk drive as recited in claim 1 , wherein a data rate of data stored in a data track of the first data zone is different than a data rate of data stored in a data track of the second data zone.

4. The disk drive as recited in claim 1 , wherein a data rate of data stored in a data track of the first data zone is the same as a data rate of data stored in a data track of the second data zone.

5. The disk drive as recited in claim 1 , wherein:

the servo tracks are banded together into a plurality of clusters; and

each data zone comprises one or more clusters.

6. The disk drive as recited in claim 1 , further comprising a second disk surface and a second head actuated over the second disk surface, wherein:

the data tracks of the second disk surface are banded together into a plurality of data zones, including a third data zone and a fourth data zone; and

a first servo tracks per inch (STPI) to data tracks per inch (DTPI) ratio of the third data zone is substantially different from a second STPI to DTPI ratio of the fourth data zone;

a plurality of logical zones are defined over the radius of the first and second disk surfaces, wherein a new logical zone begins at a boundary of a data zone on either the first or second disk surface.

7. The disk drive as recited in claim 6 , further comprising control circuitry operable to:

receive an access command from a host, the access command comprising a logical block address (LBA);

map the LBA to a absolute block address (ABA) representing a data sector recorded in one of the data tracks; and

locate the data sector in response to the ABA and the logical zones.

8. The disk drive as recited in claim 1 , wherein the first STPI to DTPI ratio is less than one and the second STPI to DTPI ratio is less than one.

9. The disk drive as recited in claim 1 , wherein the first STPI to DTPI ratio is less than one and the second STPI to DTPI ratio is greater than one.

10. A method of operating a disk drive, the disk drive comprising:

a first disk surface and a first head actuated over the first disk surface wherein:

the first disk surface comprises a plurality of servo tracks and a plurality of data tracks;

the data tracks of the first disk surface are banded together into a plurality of data zones, including a first data zone and a second data zone;

a first servo tracks per inch of the first data zone is different from a second servo tracks per inch of the second data zone; and

a first servo tracks per inch (STPI) to data tracks per inch (DTPI) ratio of the first data zone is substantially different from a second STPI to DTPI ratio of the second data zone;

a second disk surface and a second head actuated over the second disk surface, wherein:

the data tracks of the second disk surface are banded together into a plurality of data zones, including a third data zone and a fourth data zone;

a first servo tracks per inch of the third data zone is different from a second servo tracks per inch of the fourth data zone;

a first servo tracks per inch (STPI) to data tracks per inch (DTPI) ratio of the third data zone is substantially different from a second STPI to DTPI ratio of the fourth data zone; and

a plurality of logical zones are defined over the radius of the first and second disk surfaces, wherein a new logical zone begins at a boundary of a data zone on either the first or second disk surface;

the method comprising:

receiving an access command from a host, the access command comprising a logical block address (LBA);

mapping the LBA to a absolute block address (ABA) representing a data sector recorded in one of the data tracks; and

locate the data sector in response to the ABA and the logical zones.

11. The method as recited in claim 10 , wherein the first STPI to DTPI ratio is constant across the first data zone.

12. The method as recited in claim 10 , wherein a data rate of data stored in a data track of the first data zone is different than a data rate of data stored in a data track of the second data zone.

13. The method as recited in claim 10 , wherein a data rate of data stored in a data track of the first data zone is the same as a data rate of data stored in a data track of the second data zone.

14. The method as recited in claim 10 , wherein:

the servo tracks are banded together into a plurality of clusters; and

each data zone comprises one or more clusters.

15. The method as recited in claim 10 , wherein the first STPI to DTPI ratio is less than one and the second STPI to DTPI ratio is less than one.

16. The method as recited in claim 10 , wherein the first STPI to DTPI ratio is less than one and the second STPI to DTPI ratio is greater than one.

17. A method of defining data tracks on a disk surface of a disk drive, the method comprising:

writing a plurality of servo tracks on the disk surface at a varying servo tracks per inch (STPI) for defining the data tracks, wherein a first spacing between a first two of the servo tracks comprises N1 number of quantized steps;

selecting a data tracks per inch (DTPI) profile across the radius of the disk surface, wherein:

a first spacing between a first two of the data tracks comprises M1 number of quantized steps forming a N1/M1 ratio;

a second spacing between a second two of the data tracks comprises M2 number of quantized steps forming a N1/M2 ratio; and

the N1/M1 ratio is different than the N1/M2 ratio.

18. The method as recited in claim 17 , wherein substantially all of the servo tracks comprise a spacing of N1 number of quantized steps.

19. The method as recited in claim 17 , wherein a second spacing between a second two of the servo tracks comprises N2 number of quantized steps, where N2 is different than N1.

20. The method as recited in claim 17 , wherein:

the servo tracks are banded together into a plurality of clusters;

the N1/M1 ratio is constant across at least one of the clusters; and

the N1/M2 ratio is constant across at least one of the clusters.