Patent ID: 7215497

Claim:
An adjacent track data guarantee processing method for guaranteeing data of a track adjacent to a predetermined track when data is written to a desired sector of said predetermined track by a head, comprising the steps of: detecting that said head wrote data on said sector of said predetermined track with a predetermined off track amount or more; detecting whether it is possible that said head caused an off track write on said adjacent track in accordance with said detection of writing with said predetermined off track amount or more; rewriting data on the sector of said predetermined track when detecting no possibility that said off track write occurred; offset-reading the data of an adjacent sector of said adjacent track in a predetermined track direction when detecting a possibility that said off track write occurred; executing a retry read of the adjacent sector if reading was not possible in said offset read step to read the data of the adjacent sector; and rewriting data obtained by said retry read on said adjacent sector read, and said data written on the sector of said predetermined track; wherein said retry read step comprises: a first retry read step of the adjacent sector of said adjacent track; an offset DC erase step of executing an offset DC erasing the sector of said predetermined track corresponding to the adjacent sector which could not be read in said first retry read; and a step of executing a second retry read of the adjacent sector which could not be read in said first retry read.