Storage system having multiple local and remote volumes and multiple journal volumes using dummy journals for sequence control

A primary storage system is equipped with a local storage subsystem having a mirror volume of a volume in a primary storage subsystem, and a remote storage subsystem having a mirror volume of the volume in the primary storage subsystem at a secondary site. When storing a write data from a host to a volume, the primary storage subsystem determines an SEQ# to be stored in a journal corresponding to the write request, creates a journal including the relevant SEQ# and a replica of the write data, and transmits the relevant SEQ# to the local storage subsystem, which creates a journal including the relevant SEQ# and stores it in its own journal volume. But when creation of the journal including the relevant SEQ# is stopped, the local storage subsystem creates a dummy journal including the relevant SEQ# but not including the write data.