Some storage systems that manage data of host servers such as business servers include an active storage unit and a standby storage unit in case of the failure of storage, for example. The storage systems make backup copies of data of the active storage unit and store them in the standby storage unit. When it is difficult for data to be input or output between a host server and the active storage unit, a system administrator checks the status of both active and standby storage units and performs failover processing by which the active storage unit is switched to the standby storage unit.
However, conventional techniques, such as Japanese National Publication of International Patent Application No. 2004-532442 and Japanese Laid-open Patent Publication No. 2010-067115, require processes such as checking and setting of the storage units by the system administrator before the system administrator performs the failover processing by which the active storage unit is switched to the standby storage unit. Consequently, a (business suspension) period occurs in some cases in which it is difficult for the host server to continue input or output of data to or from the storage unit.