In a case where a failure has occurred in one of fabric management mechanisms, nodes resume data I/O communications without degrading performance and without changing the data I/O communication path between the nodes by switching control to the other one of the fabric management mechanisms. The fabric management mechanisms share management information with each other. When a failure occurs in either of the fabric management mechanisms, an E_Node that belongs to the domain, in which a failure has occurred, logs into a normal fabric management mechanism via a newly created management-use communication path. The normal fabric management mechanism allocates an N_Port_ID on the basis of a virtual FC domain number that has been allocated to a switch.