A disk drive with a plant having an actual plant response G(z) and a servo controller that includes a feed-forward control path that operates with a modeled plant response G0(z) in order to output a feed-forward command effort. The plant includes a transducer that is moveable from a start position to a target position according to a total control effort. In addition to the feed-forward control path, the servo controller further includes a feedback control path that outputs a feedback command effort in response to an error signal e between a desired position and an indicated position, and an adaptive control path that monitors the error signal e during the first several samples of a seek in order to characterize any modeling error between the modeled plant response G0(z) and the actual plant response G(z) and to thereafter output an adaptive command effort during subsequent samples to compensate for such modeling error and thereby make the error signal e approach zero at the end of the seek or, equally speaking, to make the transducer 80 arrive at the target position at the end of the seek notwithstanding the modeling error.