Patent ID: 8086877

Claim:
A storage device that stores data from a host computer in one or more hard disk drives via a virtual volume, the storage device comprising: a first management section that manages a storage area provided by the one or more hard disk drives on a basis of a predetermined unit created using one or more parameters; a second management section that manages, on a basis of a pool configured by at least one or more of the units under the management of the first management section, a management policy about a capacity of a plurality of pools and a threshold value of a storage capacity of the pools; a power supply control section that controls each of the hard disk drives of the unit under the management of the first management section to be in either a first turn-ON state or a second turn-ON state with a low power consumption; and a control section that selects, when the storage capacity of any of the pools exceeds the threshold value, the management policy of the pool, and any of the parameters considered optimum to serve as the unit of the storage area under the management of the first management section, and after making the power supply control section to change the state of the hard disk drive of the selected unit from the second turn-ON state to the first turn-ON state, adds the unit of the storage area to the capacity of the pool, and wherein the pools are each configured using a plurality of the units, and when the capacity of any of the pools satisfies preset pool reduction requirements, the control section transfers data stored in any of the units to any of the remaining units., and after making the power supply control section to change the state of the hard disk drive of the data-transferred unit from the first turn-ON state to the second turn-ON state, removes the unit from the capacity of the pool, and wherein for the data transfer, the control section performs the data transfer via the virtual volume, and deletes zero data in the virtual volume.