Provided is a computer system including a plurality of data storage apparatus and manages a bandwidth of a data storage apparatus according to an attribute of a storage volume. A storage system includes an interface for processing access to the storage volume from a host computer, and a control unit for controlling allocation of the storage volume to the host computer. A management computer transmits a request of setting a bandwidth to be accessed by the host computer via the interface in the storage volume to the storage system. The control unit sets the bandwidth corresponding to a ratio of processing access to each storage volume in the storage system 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.