A disk drive includes a rotatable storage disk, an actuator motor, a
slider that magnetically interacts with the storage disk, and a drive
circuitry. A portion of the slider moves between a first position wherein
the slider does not contact the storage disk and a second position
wherein the slider contacts the storage disk. The drive circuitry can
detect when the position of the slider changes between these positions.
In one embodiment, the drive circuitry monitors off-track movement of the
slider to detect when the slider has moved between these positions. The
drive circuitry can also current that is directed to the actuator motor
that is used to compensate for off-track movement to detect when the
slider moves between these positions. In yet another embodiment, the
drive circuitry monitors a rotational velocity of the storage disk to
detect approximately when the slider moves between these positions.