Abstract: According to one embodiment, in a disk drive having a disk medium on which servo data is recorded, servo-write management information is recorded on the disk medium, in the form of binary data based on the 0 or 180 degrees out of phase pattern composed of the servo burst signals included in the servo data and being out of phase. The disk drive includes a servo-data reproducing unit that reproduces the servo-data and the servo-write management information.

Abstract: According to one embodiment, a servo information writing method for use in a disk drive, for recording the servo information, forming a continuous servo track such as a spiral track. In this servo information writing method, the head is stopped when a write error is detected while the servo information is being written, and the head is then moved again at a constant speed and starts writing the servo information again, at the position where the write error has occurred.

Abstract: According to one embodiment, in a disk drive having a disk medium on which servo data is recorded, servo-write management information is recorded on the disk medium, in the form of binary data based on the 0 or 180 degrees out of phase pattern composed of the servo burst signals included in the servo data and being out of phase. The disk drive includes a servo-data reproducing unit that reproduces the servo data and the servo-write management information.

Abstract: According to one embodiment, a servo information writing method for use in a disk drive, for recording the servo information, forming a continuous servo track such as a spiral track. In this servo information writing method, the head is stopped when a write error is detected while the servo information is being written, and the head is then moved again at a constant speed and starts writing the servo information again, at the position where the write error has occurred.

Abstract: In a composite servo system or a servo system using only a sector servo system, when a head switching mode is set during a read/write operation, a CPU checks whether the cylinder of a target track of a subsequent head after switching is the same as that of a target track of a preceding head. If the target tracks are located on the same cylinder, the CPU compares offset value data of a data surface corresponding to the head before switching with that of the head after switching. If an error, as a comparison result, falls within a predtermined allowable range, a read/write operation by the head after switching is continuously executed. The CPU generates correction data used for positional correction processing for positioning the head at the center of the target position of a hard disk and temporarily stores the correction data in a data memory. The CPU executes positional correction processing on the basis of the correction data stored in the data memory.