Patent ID: 8416518

Claim:
A magnetic disk drive comprising: a disk comprising a plurality of data sectors which comprise indicator areas; a controller configured to perform a data rewrite, the data rewrite comprising reading a first data block stored in the disk in units of data sectors and writing a second data block used as a rewrite data corresponding to the read first data block to a write destination on the disk when rewriting the first data block is requested; and an indicator module configured to set an indicator indicative of an attribute associated with data rewrite in the indicator area of each sector data in the second data block when the sector data is written to the write destination, wherein: the indicator module is further configured to set a first indicator in the indicator area of a second sector data in the second data block if a read error has occurred during read of a first sector data in the first data block, wherein the second sector data corresponds to the first sector data, and wherein the first indicator comprises a read uncorrectable bit indicative of a read error; and the controller is further configured to cause the indicator module to set a second indicator in the indicator area of a fourth sector data in the second data block, the fourth sector data corresponding to a third sector data in the first data block, wherein the second indicator is configured to inherit the read uncorrectable bit of the first indicator if the third sector data is read and the first indicator is set in the indicator area of the read third sector data.