Patent ID: 7447933

Claim:
A storage system comprising: a plurality of slots adapted for use with different kinds of interface controllers, including at least a block I/O interface controller and a file I/O interface controller, said slots having the same shape; a disk controller comprising: a plurality of first interface controllers and a plurality of second interface controllers, wherein some of said first interface controllers are coupled to a network managed in a first domain and others of said first interface controllers are coupled to a network managed in a second domain; a disk adapter coupled to said first and second interface controllers; a cache memory coupled to said first and second interface controllers and to said disk adapter; a first fail-over controller for transferring processing from a source interface controller to a destination interface controller upon failure of said source interface controller, wherein said source interface controller and said destination interface controller are included among said first interface controllers and are coupled to a network managed in the same domain; a second fail-over controller for transferring processing of said destination interface controller to another interface controller included among said first interface controllers, when said destination interface controller fails; and a storage unit coupled to said disk controller, wherein said each interface controller determines the status of other interface controllers based at least on heartbeat mark information generated within the storage system.