Abstract: In a disk drive device having multiple disks on a spindle, one of the disks is written with a servo pattern prior to assembly of the servo disk with blank disks into the disk enclosure. The servo pattern consists of a first pattern arranged on each track center along one radial direction of the disk, and a second pattern arranged along the radial direction at each position corresponding to the position of each sector. Servo patterns on each of the disks, including the original servo disk are then written on each of the disks based on the original servo disk. If the disks, when assembled exhibit eccentricity, the second pattern will still be detected, permitting servo writing without complex equipment.