Disk drive for detecting a polarity error of a magnetoresistive head by detecting a sync mark

摘要

A disk drive is disclosed comprising a bias layer in a magnetoresistive (MR) head actuated over a disk having a plurality of data tracks, each data track comprising a plurality of sectors. A sync mark detector detects a sync mark pattern in a sector, wherein when the sync mark pattern is detected a sync mark detect signal and a polarity signal are generated. The polarity signal indicates when the polarity of the bias layer has deviated from a preferred polarity, wherein the polarity of the bias layer is realigned back toward the preferred polarity.