Abstract text

A backup is continued in a computer system even one storage device is stopped. In the computer system, a first storage device, upon reception of a data write request to a first storage area, stores the data in the first storage area and a second storage area, and transmits the data to a second storage device. The second storage device stores the received data in a third storage area and a fourth storage area. The first storage device, upon reception of a snapshot creation request, suspends storing of the data in the second storage area, while the second storage device, upon reception of the snapshot creation request, suspends storing of the data in the fourth storage area at timing that the same data is stored in the second storage area and the fourth storage area, and after storing of the data is suspended, transmits an identifier equal to an identifier of the second storage area to an inquiry transmission source as an identifier of the fourth storage area.