Storage system, disk control cluster, and a method for increasing the number of disk control clusters in a storage system

The storage system includes disk control clusters. Each cluster has channel IF units, disk IF units and local shared memory units. The channel IF units, disk IF units and local shared memory units in the plurality of disk control clusters are connected to each other across the disk control clusters by interconnection, global information control unit for storing management information about the disk control clusters is connected to the interconnection. Host computers and the channel IF units of the disk control clusters are connected via front-end switch for storing copy of the management information. Since the front-end switch reflects the contents of the copy of the management information on routing table, an access request from the host computer can be sent to a suitable disk control cluster.