Provided is a system in which, when connecting an external storage apparatus to a primary storage apparatus, the setting of an external volume to be mapped to the primary storage apparatus can be set to the external storage apparatus by a volume creation request to the primary storage apparatus without requiring direct setting processing on the external storage apparatus. When an administrator registers, in the primary storage apparatus, a command for setting a volume to the external storage apparatus and the administrator executes processing for setting a volume to the primary storage apparatus, if the primary storage apparatus determines that it is necessary to create a volume in the external storage apparatus, the primary storage apparatus sends the registered command to the external storage apparatus so that the administrator can set the volume to the external storage apparatus via the primary storage apparatus.