Track allocation method of disk drive

A track allocation method of a disk drive, the disk drive comprising a storage medium and a controller sending and receiving commands and data to and from a high-order device and performing writing control or reading control over said storage medium;

• wherein said storage medium is divided into a plurality of zones having different numbers of sectors for each track;
• wherein there exist a first track group having a first track width and a second track group having a second track width on said storage medium;
• wherein said first track group is divided into groups each having prescribed first numbers of tracks;
• and
• wherein, when areas of said first track group and said second track group are secured in said zone, said controller executes the steps of:
• dividing said zone into a first area for said first track group and a second area for said second track group based on a capacity ratio of said first track group to said second track group to be secured in said zone or based on a first initial value of the capacity of said first track group and a second initial value of the capacity of said second track group;
• allocating said first track group to said first area;
• allocating said second track group with said second numbers of tracks to an area in the vicinity of a defective track where the first track group with numbers of tracks cannot be secured when there exists the defective track causing prohibition of use of the entire tracks in said first area and transferring an area corresponding to said second numbers of tracks from said second area to said first area;
• and
• allocating said second track group to said second area.