A storage system is utilized to its fullest storage capacity by setting a write inhibitive attribute to a desired storage area of the storage system. The storage system has a logical volume in which data is stored and a control device which controls access to the data stored in the logical volume. A first area of a desired size is set in the logical volume, and an access control attribute is set to the first area. In response to a request made by a computer to perform access to the logical volume, the control device notifies the computer that the control device does not perform the access when an area designated by the access request contains at least a part of the first area and the access control attribute set to the first area inhibits the type of the access requested.