Patent ID: 7243166

Claim:
A storage system comprising: a channel unit that transfers data sent from an upper-level system and transfers data to said upper-level system; a plurality of cache units which are coupled to said channel unit and in which data sent from said channel unit is stored; a plurality of control units that are coupled to said plurality of cache units, and transfers or receives data to or from said plurality of cache units; a disk device that stores data written under control of each of said plurality of control units; a plurality of paths, a first one of said paths coupling a first one of said cache units to a first one of said control units, a second one of said paths coupling said first one of said cache units to a second one of said control units, a third one of said paths coupling said first one of said cache units to said channel unit; at least one first processor for controlling transfer to and from the plurality of cache units of data which is transferred from said upper-level system and received at and transferred from said channel unit; and at least one second processor for controlling said plurality of cache units to transfer data to said disk device, wherein the channel unit, the plurality of cache units and the plurality of control units are included in a disk controller, said third one of said paths not intersecting with said first one of said paths or said second one of said paths, except for at an end point connecting said third one of said paths to said first one of said cache units.