Method and apparatus for rental storage system

A storage controller comprising of:

• a channel control unit which is connected to a host computer and responds to requests from the host computer;
• a cache memory which stores data sent by the host computer under control of said channel control unit;
• a disk control unit which controls a plurality of storage devices so as to store said data stored in said cache memory into said storage devices, and
• a shared memory which stores control information according to said channel control unit and said disk control unit,
• wherein said channel control unit or said disk control unit generates a first data storage area that becomes usable from a time when a user installs said storage controller, and a second data storage area that becomes usable by the user's demands from data storage areas in said plurality of storage devices,
• wherein said storage controller manages information of usability that said first storage area and said second storage area can be used or not by said user in said shared memory, and
• wherein when said user demands changing said information of usability to said storage controller, said storage controller changes said information for usability, records the time at which said storage controller accepts user's demand and transmits said changed information of usability and said time at which said storage controller accepts user's demand to another information processor connected to said storage controller via a network.