Patent ID: 7242550

Claim:
A magnetic disk apparatus for reading read data from and writing write data to magnetic disks on a virtual-track-number-specific basis, absolute track numbers being track numbers of tracks formed on the magnetic disks by an SSTW, physical track numbers being track numbers into which the absolute track numbers are converted such that when a reference magnetic head is fixedly placed at any given position on the magnetic disks, identical track numbers are read from the reference magnetic head and from another magnetic head, and virtual track numbers being track numbers into which the physical track numbers are converted such that a track pitch becomes suitable for each magnetic head and also for each area on the magnetic disks, said magnetic disk apparatus comprising: a first conversion unit configured to convert a physical track number into an absolute track number by making a track pitch in an absolute track area formed by said another magnetic head wider by a given amount than a track pitch in a corresponding absolute track area formed by said reference magnetic head if a number of absolute tracks is larger in the absolute track area of absolute tracks formed by said another magnetic head than in the absolute track area of absolute tracks formed by said reference magnetic head although a number of physical tracks is identical in corresponding physical track areas between different magnetic disks, said given amount being commensurate with an unused area corresponding to a difference in the number of absolute tracks between the absolute track area of absolute tracks formed by said another magnetic head and the corresponding absolute track area of absolute tracks formed by said reference magnetic head.