Abstract: Provided is a computer system comprising: an input/output switch coupled to a plurality of input/output devices; a server which is coupled to the input/output switch and, which uses the plurality of input/output devices; and a management computer coupled to the input/output switch and the plurality of input/output devices. The management computer manages pieces of management information including a port of the input/output switch coupled to the each of the plurality of input/output devices, an association of a device coupled to the each of the plurality of input/output devices, and a usage ratio of the each of the plurality of input/output devices; selects at least one of the input/output devices of which the usage ratio is smaller than a first predetermined threshold according to the pieces of management information; and processes, by another input/output device coupled to the input/output switch, a request for the selected input/output device.