Patent ID: 8531793

Claim:
A magnetic recording disk drive comprising: a magnetic recording disk having a plurality of concentric data tracks on a surface of the disk for the storage of data; a write head associated with said disk surface for generating a magnetic write field to write data to the data tracks; a read head for reading data written in the data tracks; a controller for controlling the writing of data by the write head to the data tracks; and memory coupled to the controller and containing a program of instructions readable by the controller for minimizing the effect of encroachment of the write field on data tracks within a range between −N tracks and +N tracks of the data track being written, the program of instructions undertaking the method acts comprising: (a) maintaining in memory a count for each track, the memory including a table of 2N tracks having range numbers between −N and +N and corresponding 2N increment values; (b) for each writing of data to a track, determining the range number for each track within said range, recalling from the table in memory the corresponding increment value and increasing said count by said recalled increment value for each track within said range; and (c) when a count for a track reaches a predetermined threshold, reading the data from said threshold-count track and rewriting the data read from said threshold-count track.