A switch control system including a storage unit, a switch which logically sets a network topology between the storage unit and a plurality of computers, and a management server which communicates with the switch and the storage unit, wherein the storage unit includes at least one disk; wherein the management server comprises a memory and a processor, wherein the memory holds the network topology which is set by the switch, wherein when a failure is detected in one of the computers currently being used, the processor of the management server refers to the memory to change the network topology for the computer where the failure is detected and another computer which substitutes the computer where the failure is detected, and instructs the switch with the changed network topology so as to cause the switch to logically set the changed network topology, and wherein the management server controls the disk of the computer where the failure is detected to be accessible.