Abstract: A recording/playback apparatus includes an upper control unit which transmits a composite command, which includes a real processing command and a virtual command, to a disk device. The disk device performs a process until a point of time when an operation cannot be continued unless the virtual command is changed to the real processing command to be operated beforehand. Instead of standing by after the real processing command is completed, the disk device can voluntarily operate beforehand in response to the virtual command, while selecting an optimum seek speed or disk rotation speed. The recording/playback apparatus can thus maintain the continuity of continuous data and perform an optimum operation in accordance with an expected performance while switching speeds of seek and disk rotation in detail.

Abstract: According to a recording/playback apparatus of the present invention, as in FIG. 1, an upper control unit (9) transmits a composite command comprising a real processing command and a real command to a disk device (13), and the disk device (13) performs a process until a point of time when an operation cannot be continued unless the virtual command is changed to the real processing command to be operated beforehand, in response to the virtual command, after the real processing command is completed, while selecting an optimum seek speed or disk rotation speed.

Abstract: A mirroring RAID system is provided at low cost using a single magnetic disk drive. The magnetic disk drive comprises a host I/F 2 for receiving data transferred from an external host device, a magnetic disk 10 for recording data thereon, and a magnetic head 11 and preamplifier circuit 16 for recording data on the magnetic disk 10, wherein the magnetic disk drive further comprises a control CPU 5 which, based on the transfer speed of the data transferred from the external host device and on performance indices unique to the magnetic disk drive, computes the number of duplicate data recordable times representing the number of times that the transferred data can be recorded in duplicate on the magnetic disk 10, and which controls the magnetic head 11 and preamplifier circuit 16 so that the data transferred from the external host device will be recorded on the magnetic disk 10 a number of times that does not exceeds the number of duplicate data recordable times thus computed.