Patent ID: 7568119

Claim:
A storage control device connected to a host device and plurality of storage devices, comprising: a plurality of controllers connected to each storage device via differing lower communications networks, wherein each controller comprises: an upper communications unit conducting communications with the host device via an upper communications network; a lower communications unit conducting communications with each storage device via a lower communications network; a control unit inputting and outputting data with each storage device via the lower communications unit based on instructions input from the host device via the upper communications unit; a switching unit switching the connection destination of the lower communications unit between the lower communications network and the lower communications network of a partner controller; a fault detection unit detecting faults occurring in the lower communications network; a switching request unit outputting a switching request for inducing switching from the lower communications network, in which a fault is detected, to the lower communications network of the partner controller; a preparation status detection unit detecting whether or not switching preparations are complete; and a switching permission unit permitting switching with the switching unit based on the switching request when a preparation status detection unit detects that switching preparations have been completed and the switching request is received from the switching request unit; wherein switching to the lower communications network of the partner controller without completing the switching preparations will result in failure.