While a large amount of files can be intensively managed, the capacity scalability is limited by the number of magnetic disk drives and the number of magnetic tape drives which can be connected to a system, thereby failing to provide satisfactory long-term management for a large amount of information which increases more and more over time. A storage system of the present invention is designed for connection with a heterogeneous storage which can be controlled by the storage system, and creates file systems in a storage area reserved within the storage system and in a storage area provided by the heterogeneous storage.