Patent ID: 7428624

Claim:
A computer system, comprising: a host computer; a storage system coupled to the host computer via a network and including a storage volume to be accessed by the host computer; and a management computer for managing the host computer and the storage volume, wherein: the storage system includes an interface for processing access to the storage volume from the host computer, and a control unit for controlling allocation of the storage volume to the host computer and; the management computer transmits a request of setting a bandwidth corresponding to a ratio of processing access to the each storage volume in the storage system, in the storage volume to the storage system and; the control unit sets the bandwidth in the storage volume based on the request from the management computer, and allocates the storage volume having the bandwidth requested by the host computer set therein to the host computer, to be accessed by the host computer to the allocated storage volume and; the storage volume includes a first storage volume having a first bandwidth set therein and a second storage volume having a second bandwidth set therein; and the control unit releases the allocated first storage volume, allocates the second storage volume having the second bandwidth set therein to the host computer, and sets the allocated second storage volume to be accessed by the host computer, thereby modifying the bandwidth of the storage volume allocated to the host computer from the first bandwidth to the second bandwidth.