Storage apparatus having virtual-to-actual device addressing scheme

A storage apparatus comprising:

• a storage unit;
• and
• a controller coupled to said storage unit,
• wherein control of inputting/outputting data from/to a device provided in said storage unit is executed in accordance with a request received by said storage apparatus from a host computer,
• wherein an actual device of the storage apparatus corresponds to a virtual device which is external to said storage apparatus, and
• wherein said controller performs:
• a process for mapping an actual device address corresponding to a virtual device address of said virtual device, in accordance with a specification of the actual device to be mounted or unmounted to correspond to said virtual device, and storing and retaining mapping information obtained from the mapping in a first table;
• and
• a data input/output process for receiving an access request from the host computer for data input/output in which said virtual device address is specified, obtaining the actual device address mapped to said specified virtual device address in said first table, and accessing the actual device by said obtained actual device address,
• wherein said actual device to be mounted or unmounted with respect to said virtual device is specified from a logical partition controller included in said host computer, wherein said logical partition controller sets logical partitions of virtual devices to be objects so that resources of said host computer are used based on said logical partitions, and
• wherein said controller is configured to perform high speed access to the actual device from the host computer.