Disk drive accounting for sinusoidal offset between heads when executing a rotational position optimization algorithm

A disk drive comprising:

• a plurality of disk surfaces each comprising a plurality of data tracks, wherein each data track comprises a number of data sectors and a number of servo sectors;
• a plurality of heads including at least one head actuated over each disk surface;
• and
• control circuitry operable to:
• measure a radial offset between a first head and a second head at a plurality of points along a circumference of a corresponding first and second disk surface to generate a plurality of radial offsets;
• access the data tracks on the first disk surface;
• switch from the first head to the second head near a first servo sector of the first disk surface;
• and
• measure the radial offset between the first head and the second head corresponding to the first servo sector in order to update the radial offset.

A method of operating a disk drive comprising:

• measuring a radial offset between a first head and a second head at a plurality of points along a circumference of a corresponding first and second disk surface to generate a first plurality of radial offsets;
• determining a first radial offset and a second radial offset based on the first plurality of radial offsets, wherein the first radial offset corresponds to approximately a maximum in the first plurality of radial offsets and the second radial offset corresponds to approximately a minimum in the first plurality of radial offsets;
• storing a plurality of access commands in a command queue;
• and
• executing a rotational position optimization (RPO) algorithm to select a next access command to execute from the command queue, wherein the RPO algorithm is responsive to the first and second radial offsets.

A method of operating a disk drive comprising:

• measuring a radial offset between a first head and a second head at a plurality of points along a circumference of a corresponding first and second disk surface to generate a plurality of radial offsets;
• accessing data tracks on the first disk surface;
• switching from the first head to the second head near a first servo sector of the first disk surface;
• and
• measuring the radial offset between the first head and the second head corresponding to the first servo sector in order to update the radial offset.