A storage system having a plurality of disk controllers for accepting computer access through a SAN, and a plurality of file servers for accepting computer access through a LAN. The disk controllers and file servers are connected through a connection unit to a plurality of disk drive units in a disk pool. A disk pool management unit manages the relationships between the disk controllers and file servers and the disk drive units used by the respective disk controllers and file servers, and sends information identifying the usable disk drive units to the respective disk controllers and file servers. The disk controllers and file servers use the disk drive units based on the received usable disk information.