Shingled magnetic recording disk drive with inter-band disk cache and minimization of the effect of far track erasure on adjacent data bands

摘要

A shingled magnetic recording hard disk drive that uses writeable cache tracks in the inter-band gaps between the annular data bands minimizes the effect of far track erasure (FTE) in the boundary regions of annular data bands caused by writing to the cache tracks. Based on the relative FTE effect for all the tracks in a range of tracks of the cache track being written, a count increment (CI) table or a cumulative count increment (CCI) table is maintained. For every writing to a cache track, a count for each track in an adjacent boundary region, or a cumulative count for each adjacent boundary region, is increased. When the count value for a track, or the cumulative count for a boundary region, reaches a predetermined threshold the data is read from that band and rewritten to the same band.

主权项

1. A shingled magnetic recording disk drive comprising:
a magnetic recording disk having a recording surface with a plurality of concentric shingled data tracks arranged in annular bands separated by annular inter-band gaps, each band having a boundary region of tracks adjacent a gap, whereby each gap is located between adjacent boundary regions and wherein each gap contains at least one writable cache track; 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 in the boundary regions when a cache track is being written in an inter-band gap, the program of instructions undertaking the method acts comprising:
(a) maintaining in memory at least one count for each boundary region;(b) for each writing of data to a cache track, increasing said at least one count for an adjacent boundary region by a predetermined increment, said increment being determined from the number of tracks between the cache track being written and said adjacent boundary region; and(c) when a count reaches a predetermined threshold, reading the data from the band containing said threshold-count boundary region and rewriting the data read from said band.