Patent ID: 7146389

Claim:
A method for rebalancing disks among multiple network storage devices in a virtualized network storage system including a network connecting the multiple network storage devices and a virtualizing device, wherein said multiple network storage devices virtually appear to clients as if the network storage devices were a single network storage device owing to the functions of said virtualizing device, the method comprising: a rebalancing process which comprises the steps of: a disk rebalancing step that includes moving one or more files stored in a first network storage device of said multiple network storage devices to a second network storage device of said multiple network storage devices; and a termination judging step that includes examining free disk spaces in individual network storage devices to judge whether to continue disk rebalancing processing based on a maximum value and a minimum value of the free disk spaces and a first threshold and, if the processing should be continued, going back to said disk rebalancing step and if the processing is not to be continued, terminating the processing; and a monitoring process which comprises the steps of: a first start of rebalancing determining step that includes periodically examining the free disk space in each of said multiple network storage devices, and judging based on the maximum value and minimum value of the free disk spaces and a second threshold whether to start the rebalancing process; and a rebalancing starting step in which, if it is judged in the first start of rebalancing determining step that rebalancing should be started, the rebalancing process is started.