Patent ID: 7870460

Claim:
A magnetic disk drive configured to perform data refreshing, the magnetic disk drive comprising: a magnetic disk comprising a backup-track which is used for backup of data refreshing and a refresh-track of which data is refreshed; and a controller configured to control a data refresh operation of reading L blocks of data written in the refresh-track, writing the read data to the backup-track, and then rewriting the read data to the refresh-track for which the reading has been performed, such that the data refresh operation corresponds to N revolutions of the magnetic disk and satisfies relations shown by a following expression: ( Bb+Br )× Td×L=Bb×Br ×{( Td×N )−2× Ts} where Bb is the number of blocks included in a backup-track, Br is the number of blocks included in a track subject to data refreshing, Td is a time period which a magnetic disk needs to rotate once, L is the number of blocks of data written in a track subject to data refreshing, N is the number of revolutions of a magnetic disk which corresponds to data refreshing, and “2×Ts” is a seek time which a head needs to move back and forth between a track subject to data refreshing and a backup-track.