A disk drive includes a rotatable data storage disk, a transducer, an
actuator, and a controller. The transducer is configured to read and
write data on the disk. The actuator is configured to position the
transducer relative to defined portions of the disk. The controller is
configured to determine how many times data has been written to the
defined portions of the disk. The controller is also configured to
refresh data residing at a particular one of the defined portions of the
disk when the number of times data has been written to the particular
defined portion of the disk satisfies a threshold value.