A management server obtains configuration information of an active server and creates a logical partition in a backup server so as to correspond to the active server. The backup server starts up the created logical partition. And when the created logical partition reaches a predetermined state, the backup server releases allocation of the first processor resource to the logical partition, thereby the logical partition stands by. The management server, when detecting an error occurred in the active server, stops the active server and searches the logical partition having same configuration as the active server in which error is detected, and enables allocation of the first processor resource to the searched logical partition, thereby completing the start-up of the logical partition.