Abstract: A magnetic disk apparatus includes a magnetic disk with normal and double servo sectors arranged alternately. If a servo interruption period corresponding to adjacent first servo sectors is a first servo interruption period, then a second servo interruption period that is a servo interruption period corresponding to adjacent first servo sector and second servo sector is equal to or less than half of the first servo interruption period.

Abstract: This invention relates to head position control method for a disk device the uses a disk medium whose tracks have been formatted externally, and the disk device that effectively uses the range of motion of an actuator. In a disk device that has a disk medium (2), head (3), actuator (5), a control circuit (8), there is a conversion mechanism (31) that sets a data area in the writing range of the disk (2) that corresponds to the range of motion of the actuator, and converts a logical address to a physical address in the data area. This invention makes it possible to set a storage capacity that makes maximum use of the range of motion of the actuator for any device, even when there is position offset in the range of motion of the actuator.

Abstract: Two-phase servo patterns are recorded on a servo area of a data medium of a data storage apparatus such that patterns Q+, N+, N- and Q- are recorded in the stated order, there being a phase shift of 90 degrees between position information N and position information Q.

Abstract: A disk apparatus wherein a disk is rotated by a rotating motor, and a source power supplied to the rotating motor is monitored, which includes: a memory unit for storing an initial source voltage value before a process of a rotating motor acceleration is started; a detecting unit for periodically detecting a source voltage value related to the source power; a comparing unit for comparing the source voltage value, detected by the detecting unit during the process of the rotating motor acceleration, with the initial source voltage value stored in the memory unit, and for outputting a voltage fluctuation indicated by a difference between the source voltage value and the initial source voltage value; and a control unit for setting a quantity of the source power supplied to the rotating motor, to a smaller quantity in response to the voltage fluctuation output by the comparing unit.