At least one second I/O switch which a plurality of I/O devices is coupled to is coupled to at least one first I/O switch to which a plurality of servers is coupled. A configuration in which all servers that are coupled to the first I/O switch can be coupled to all I/O cards that are coupled to the at least one second I/O switch that is coupled to the first I/O switch is executed. The controller receives the specifications of a server unit and an I/O device unit that is to be coupled to the server unit. The controller executes a setting in which at least one I/O device that configures the specified I/O device unit is allocated to at least one server that configures the specified server unit to the second I/O switch to which the at least one I/O device is coupled.