A cluster-structured storage system where the access performance from a host system to a volume in an alternative-type storage subsystem is not degraded during failover, and a method for managing volume in the storage system. In this storage system, storage areas forming a primary storage subsystem and storage areas forming a standby storage subsystem are both hierarchized and correspondence relationships are established between the hierarchical levels. A copy destination volume is located on a hierarchical level associated with the hierarchical level of a copy source volume.