Patent ID: 7840771

Claim:
A management method for a computer system comprising a host computer and a storage system coupled to the host computer, wherein the storage system comprises a physical disk storing data sent from the host computer and a disk controller controlling input or output of the data to or from the physical disk, wherein the disk controller provides the host computer with a thin provisioning volume to which a storage area of the physical disk is to be allocated in response to a write request sent from the host computer, wherein the host computer recognizes the thin provisioning volume as a volume having a more capacity than a capacity of the storage area of the physical disk allocated to the thin provisioning volume, said method comprising: obtaining, from the storage system, a first capacity of the storage area of the physical disk allocated to the thin provisioning volume by utilizing an identifier which is to be used by the storage system to identify the provisioning volume; obtaining, form the storage system, a second capacity of the thin provisioning volume recognized by the host computer by utilizing the identifier; calculating an improvement capacity by subtracting the first capacity from the second capacity; calculating an improvement ratio by dividing the calculated improvement capacity by the first capacity; and displaying the calculated improvement ratio.