In the case of adding an arbitrary hard disk drive, the hard disk drive is operated in a specific operation mode suited for that hard disk drive. As triggered by the attachment of a hard disk drive to a disk adapter, a processor operates the hard disk drive in a predetermined operation mode based on predetermined parameter information that has been prepared in advance. The hard disk drive stores, in advance, particular parameter information including information about the specific operation mode suited for operation. The processor reads the particular parameter information from the hard disk drive in the predetermined operation mode and operates the hard disk drive in the specific operation mode based on the particular parameter information.