A non-transitory computer readable storage medium having stored thereon a computer program that causes a computer to implement a method of controlling a storage device that administrates data to be mounted on a client terminal, the data categorized into a plurality of generations, and that controls data in response to a request to mount data received from the client terminal, the method comprising:
- storing, in a database storage server, a table including disk information of a storage unit, the disk information being associated with each of operational data, backup data, and standby data, the storage unit storing therein a first generation of data that is currently under operation as the operational data, a second generation of data that had functioned as the operational data as the backup data, and a third generation of data that is to be in operation as the standby data;
- modifying, at a switching unit, the disk information in the table by switching the first and the third generations such that the third generation is stored as the operational data, and the first generation is stored as the backup data, wherein only disk information in the table is modified and there is no change in volumes of the storage unit;
- mounting the stored operation data onto the client terminal when receiving the request, and continuing the mount on the client terminal by using the backup data when switching generations while the operation data is mounted on the client terminal;
- and
- receiving, at a disk operations unit, a control message from the switching unit to execute the deletion or copying of a volume thereby creating a new operating volume and giving the operating volume a name.