In an information processing system including host computers and disk devices, each of an execution-node host and a standby-node host includes an I/O request unit and an access-right change command unit. The I/O request unit issues an I/O request. The access-right change command unit transmits an access-right change command. The access-right change command results from causing I/O-enable/disable information and the host identification information to correspond to each other. The disk device includes an access control table, an access control unit, and an access-right change unit. The access control table stores information of the access-right change commands from the hosts. The access control unit judges the execution enablement/disablement for the I/O requests from the host identification information and the access control table. The access-right change unit, in accordance with the access-right change commands from the hosts, changes in batch the I/O-enable/disable information on each host basis within the access control table.