Patent ID: 7149886

Claim:
A storage system comprising: a plurality of disk devices which includes a plurality of logical volumes: a disk controller including a plurality of disk control units each of which is connectable to the plurality of disk devices, and a common mutual connecting network which connects the plurality of disk control units with each other; and a supervise processor, wherein each of plurality of disk control units comprises: a plurality of first interfaces connectable to a host computer via a storage area network; a plurality of second interfaces connectable to the plurality of disk devices; and a cache memory unit storing data temporarily; wherein the plurality of first interfaces, the plurality of second interfaces, and the cache memory of one of the plurality of disk control units are connected to the plurality of first interfaces, the plurality of the second interfaces and the cache memory of the other ones of the plurality of disk control units by the common mutual connecting network, wherein the supervise processor monitors and calculates an access frequency from the host computer to one of the plurality of logical volumes by using a first logical path and a second logical path, wherein the first logical path includes the storage area network, one of the plurality of first interfaces of the one of the plurality of disk control units, and one of the plurality of second interfaces of the one of the plurality of disk control units, wherein the second logical path includes the storage area network, one of the plurality of first interfaces of the other one of the plurality of the disk control units, the common mutual connecting network, and one of the plurality of the second interfaces of the one of the plurality of disk control units.