Memorisation device which connects to an external memory

The present invention relates to a first memory connected to a second memory, and an external device (180) of the first provided to a host (100) as a device of the second. The second memory includes a cache control having a plurality of cache adapters (150), each controlling disc (157) and a cover (154), a protocol converter including a plurality of protocol adapters (140) switching requests from the host (100) to the adapters (150), a management adapter (160), and an internal network (170) connecting these adapters. By connecting the first memory to an adapter (140), the first and second memories are connected. The second memory executes a processing device (180) by the cache control, or the connection to the first memory via the protocol converter without the cache control executes processing therefor.