Patent ID: 7680847

Claim:
A method for rebalancing unused capacities among network storage devices in a virtualized network storage system which includes a network coupled to the network storage devices, a virtualizing device which provides, to a client computer, a single storage device configured by the network storage devices, the method comprising the steps of: monitoring unused capacities of network storage devices of which unused capacity is smaller than a first predetermined value; comparing between a first unused capacity of a first network storage device among monitored network storage devices and a second unused capacity of a second network storage device among monitored network storage devices, the first unused capacity is smaller than a second predetermined value, the second unused capacity is biggest among the network storage devices; as a result of comparison, if difference between the first unused capacity and the second unused capacity is more than a third predetermined value, then, moving, via the network, one or more files from the first network storage device to the second file network storage device; judging whether the difference between the first unused capacity and the second unused capacity is smaller than the third predetermined value; if the difference between the first unused capacity and the second unused capacity is smaller than the third predetermined value, terminating the step of moving; and if the difference between the first unused capacity and the second unused capacity is larger than the third predetermined value, continuing the step of moving.