Abstract: A backup control device includes a master storage unit, a snapshot storage unit, and a control unit. The master storage unit stores master data. The clone storage unit stores latest differential data of the master data. The snapshot storage unit stores snapshot data which is data at time of acquisition of backup of the clone storage unit. The control unit saves differential data into the snapshot storage unit when the differential data is present in the clone storage unit, and does not perform acquisition of the snapshot data when differential data is absent in the clone storage unit.

Abstract: Disclosed is a backup control device for controlling such that backup or restore can be executed between different apparatuses even in environments not allowing backup or restore therebetween. The backup control device includes a backup control unit that, determines whether a backup to be executed is an initial backup or a differential backup on the basis of a volume management table, and generates a different copy table, determines, for each first sector number, the necessity or non-necessity of the backup on the basis of the copy table, and requests a storage apparatus to store information stored in a sector with the first sector number in a sector with a second sector number in a backup volume corresponding to the first sector number.

Abstract: The disk array device includes an allocation control unit that allocates a physical sector to a logical sector, and an erasure control unit that erases data written on a logical sector. The allocation control unit stores a logical sector and a physical sector allocated thereto in a translation table in association with each other, and stores allocation information representing that the physical sector is allocated to the logical sector, in an allocation table. The erasure control unit registers logical disk information specifying a logical disk, to which an erasure request has been made, in an under-erasure table, specifies a physical sector allocated to a logical sector formed in the logical disk to which the erasure request has been made, based on the allocation table and the translation table, and performs erasure processing on the specified physical sector.