A computer system, comprising: a service server on which an application; a storage server for storing data used by the application; and a management server for managing the service server and the storage server, the service server including a cache device which a server cache for temporarily storing data is set, and including an operating system and an I/O request monitoring unit for monitoring an I/O request issued by the application, and issuing a dummy I/O request for controlling an arrangement of data in the server cache in a case where a predetermined condition is satisfied, the management server including a cache optimization unit for generating a control policy for issuing the dummy I/O request.