COMPUTER SYSTEM AND MANAGEMENT METHOD THEREOF

The present invention makes it possible to dynamically and optimally change QoS while taking the balance of a system as a whole into consideration. With the present invention, communications parameters comprising band allocation information with respect to a plurality of interfaces of communications paths are set at a management device, and a host device, a switch device, and a storage device communicate based on the communications parameters that have been set. Then, in the system operation stage, the management device or the switch device acquires statistical information comprising band usage amounts with respect to the communications paths among a port of the host device, a port of the storage device, and a port, of the switch device, changes, based on the statistical information, the band allocation that has been set with respect to the plurality of interfaces, and, further, determines whether or not the band allocation as changed is appropriate with respect to the system (see FIG. 9).