Patent ID: 8572422

Claim:
A disk array apparatus, comprising: a storage unit for storing data which is transmitted from a host device; a plurality of volatile storage units for temporarily storing the data transmitted/received between the host device and the storage unit; a data control unit for controlling transmission/reception of the data; a power supply unit for supplying power, which is supplied from an external power supply, to the plurality of volatile storage units and the data control unit; a battery unit for supplying power to the data control unit and the volatile storage unit when power being supplied from the external power supply is shut OFF without executing power supply shut down processing; wherein a power supply control unit switches the power supply to the plurality of volatile storage unit to power saving mode when the power being supplied from the external power supply is shut OFF without executing the power supply shut down processing, and cancels the power saving mode in a part of the volatile storage unit of the plurality of volatile storage units when the data stored in the part of the volatile storage unit is stored in the nonvolatile storage unit; and the data save control unit causes the nonvolatile storage unit to store the data stored in the part of the volatile storage unit for which the power saving mode is canceled.