Magnetic disk device capable of reallocating address corresponding to defective sector to alternative sector

A magnetic disk device comprising:

• a disk that includes a plurality of tracks, each track including a plurality of sectors for storing data;
• a head that writes data to and reads data from the plurality of sectors;
• and
• a controller that is configured to
• determine that a first sector disposed on a slip track of the disk is not able to be read and is a defective sector;
• determine that a second sector of the plurality of sectors is disposed along a line that extends through the first sector and a defective sector included in a first list of defective sectors and;
• register the second sector in the first list of defective sectors;
• and
• reallocate an address corresponding to the second sector to an alternative sector included on the disk.

A method of reading data in a magnetic disk device that includes a disk having a plurality of sectors for storing data, the method comprising:

• determining that a first sector of the plurality of sectors is not able to be read and is a defective sector;
• determining that a second sector of the plurality of sectors is disposed along a line that extends through the first sector and a defective sector included in a first list of defective sectors;
• registering the second sector in the first list of defective sectors;
• and
• reallocating an address corresponding to the second sector from a first alternative sector included on the disk.