Network storage configuration management

The present invention allows a pair to be formed between a plurality of discrete volumes and the progress thereof to be managed by means of a remote operation from a management server. Management server instructs respective host computers to generate configuration files . Next, management server instructs host computers to start up HORCM (Hitachi Remote Copy Module) instances . The generation of the configuration files and the startup of the HORCM instances can be separated. In one mode, configuration files are generated and the HORCM instances are started up, while, in another mode, only configuration files are generated. In yet another mode, the HORCM instances are started up when predetermined conditions are fulfilled. A more flexible operation can thus be performed.