US Patent 7656599 Control apparatus, storage apparatus, and computer product

A rewrite determining unit of a hard disk apparatus acquires a servo signal that includes an offtrack amount corresponding to each servo frame from a position information memory, and determines whether a write fault has occurred based on the servo signal. If a write fault has occurred, the rewrite determining unit determines a rewrite sector count, and a write controller controls a hard disk controller so that rewriting is performed to correspond to the rewrite sector count determined by the rewrite determining unit.