US Patent 7240139 Disk array control device with two different internal connection systems

A disk array control device which includes a plurality of channel interface (IF) units, a plurality of disk IF units, a cache memory unit, and a shared memory unit. The connection system between the plurality of channel IF units and plurality of disk IF units and the cache memory unit is different from the connection system between the plurality of channel IF units and plurality of disk IF units and the shared memory unit. In the invention the plurality of channel IF units and the plurality of disk IF units are connected via a selector to the cache memory unit whereas the plurality of channel IF units and the plurality of disk IF units are directly connected to the shared memory unit with no selectors.