Patent ID: 7054089

Claim:
A magnetic disk storage system comprising: a first motor which rotates a magnetic disk; a first motor drive circuit which rotatably drives the first motor; a magnetic head which reads information on a storage track on the magnetic disk and is adapted to make smaller a gap between the magnetic head and a surface of the magnetic disk as the rotational speed of the first motor increases; a second motor which moves the magnetic head above the magnetic disk; a boost circuit which boosts a voltage which is generated by rectifying a first back electromotive force of the first motor, so as to generate a first voltage when a first power supply to the magnetic disk storage system is interrupted; a second motor drive circuit which drives the second motor in accordance with a control of a drive control circuit by using the first voltage as a second power supply to the second motor drive circuit when the first power supply to the magnetic disk storage system is interrupted; a central processing unit which supplies the drive control circuit with a first current command value for the second motor drive circuit by using the voltage as a third power supply to the central processing unit so as to perform a retract control, said retract control including shifting the magnetic head to a standby position when the first power supply to the magnetic disk storage system is interrupted; and the drive control circuit which controls the second motor drive circuit in accordance with the first current command value by using the first voltage as the second power supply to the drive control circuit when the first power supply to the magnetic disk storage system is interrupted.