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

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.

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.