It is an object of the present invention to use the resources of various sites in an effective manner. The first site has a first DB access part in use. The second site has a second DB access part in use in addition to a first DB access part for standby corresponding to the first DB access part in use. The second DB access part in use writes data into a second storage device that is assigned to the second DB access part itself. The inter-site monitoring server monitors the first DB access part in use and the second DB access part, and in cases where it is detected that the first DB access part in use has gone down, the inter-site monitoring server switches the first DB access part for standby to the DB access part in use.