Patent ID: 7415589

Claim:
A system comprising: a plurality of storage systems each including a control section and storage devices whereby to have the functionality of storing data into storage areas, wherein a first storage system retains first data as replication target data, a second storage system retains second data as replication data of the first data, and a third storage system retains third data as replication data of the first data, wherein in accordance with an instruction received from a host computer, the first storage system performs data updating of the first data, creates information regarding the data updating as a first journal including an identifier of data update sequence, stores the journal into a storage area in the first storage system, and makes an instruction including the identifier for data updating of the second data to the second storage system in synchronization with the data updating of the first data via a communication line between the first and second storage systems, wherein in accordance with the instruction for the data updating, the second storage system performs the data updating of the second data, creates information regarding the data updating as a second journal by using information including the identifier received from the first storage system, and stores the second journal into a storage area in the second storage system, wherein in asynchronization with the data updating of the first and second data, the third storage system retrieves the second journal from the second storage system via a communication line between the second and third storage systems, stores the second journal as a third journal into a storage area of the third storage system, and data updating of the third data based on the identifier in accordance with the data update sequence of the first data in the first storage system by using the third journal, and wherein, in the event of failure occurrence, transfer of the each individual journal is performed between the storage systems and data updating is performed by using the transferred journal, wherein each storage system includes at least one group of data volumes for which data integrity is to be maintained, and wherein a journal volume is assigned to each of said at least one group of data volume.