Magnetic disk device and method

A method for controlling a magnetic disk device comprising a magnetic disk and a magnetic head,

• the magnetic disk comprising:
• a plurality of first servo sectors arranged in a circumferential direction at intervals, the plurality of first servo sectors each comprising:
• a first area in which first information including a preamble, a servo mark, and a Gray code is written;
• and a second area in which second information including a burst pattern is written, the second area disposed after the first area in a write and read direction along the circumferential direction;
• and
• a plurality of data areas each disposed between two first servo sectors adjacent to each other in the circumferential direction,
• wherein the plurality of first servo sectors comprises a plurality of second servo sectors and a plurality of third servo sectors,
• one or more of the plurality of third servo sectors are arranged between two adjacent second servo sectors of the plurality of second servo sectors, and
• a length of the first area comprised in each of the plurality of third servo sectors in the circumferential direction is longer than a length of the first area comprised in each of the plurality of second servo sectors in the circumferential direction,
• the method comprising:
• in a write operation of writing data in one or more of the plurality of data areas using the magnetic head, demodulating the first information and the second information when the magnetic head passes through one of the plurality of second servo sectors and demodulating the second information without demodulating the first information when the magnetic head passes through one of the plurality of third servo sectors;
• and
• in a read operation of reading data from one or more of the plurality of data areas using the magnetic head, demodulating the first information and the second information when the magnetic head passes through one of the plurality of second servo sectors and demodulating the first information and the second information when the magnetic head passes through one of the plurality of third servo sectors.