A storage subsystem and a storage controller adapted to take advantage of high data transfer rates of fiber channels while offering enhanced reliability and availability and capable of connecting with a plurality of host computers having multiple different interfaces. A loop is provided to serve as a common loop channel having fiber channel interfaces. Host interface controllers (HIFC) connected to host computers having different interfaces permit conversion between the fiber channel interface and a different interface as needed. Control processors, shared by the host interface controllers, each reference FCAL (fiber channel arbitrated loop) management information to capture a frame having an address of the processor in question from among the frames passing through the loop. I/O processing is then carried out by the controller in accordance with a range of logical unit numbers (LUN) set in the captured frame.