| 摘要 |
To keep to a minimum a frequency of an occurrence of a necessity of changing a power consumption condition of a storage device from an energy saving condition to a normal condition. A controller unit and a plurality of storage devices being furnished, a log area and a normal area are provided based on the plurality of storage devices. A quantity of log storage devices forming a basis of the log area is smaller than a quantity of normal storage devices forming a basis of the normal area. In an operational period, in which the controller unit is in a condition in which it may accept an input-output command from an external apparatus, a power consumption condition of the log storage devices is constantly in a normal condition in which an input or output of data can be carried out, while a power consumption condition of the normal storage devices, during a specified period in the operational period, is in an energy saving condition, which is a condition in which a power consumption is lower than in the normal condition. The controller unit, when receiving an input-output command from the external apparatus, in the event that the power consumption condition of the normal storage devices is the normal condition, carries out an input or output with respect to both the normal area and the log area.
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