A computer system that includes a plurality of servers, and a shared I/O
subsystem coupled to each of the servers and to one or more I/O
interfaces. The shared I/O subsystem services I/O requests made by two or
more of the servers. Each I/O interface may couple to a network,
appliance, or other device. The I/O requests serviced by the shared I/O
subsystem may alternatively include software initiated or hardware
initiated I/O requests. Different servers coupled to the shared I/O
subsystem may use different operating systems, and each I/O interface may
be used by two or more servers.