Abstract: Methods, apparatuses and systems directed to virtualized access to input/output (I/O) subsystems. In one implementation, the present invention allows multiple stand-alone application servers or virtual servers to share one or more I/O subsystems, such as host-bus adapters and network interface cards. In one implementation, I/O access is managed by one or more virtual I/O servers. A virtual I/O server includes a multiplexer, and associated modules, that connect application servers over an I/O switch fabric with one or more HBA and/or NIC drivers. Implementations of the present invention can be configured to consolidate I/O access, allowing multiple servers to share one or more HBAs and NICs; dynamic control over network and storage I/O bandwidth; and provisioning of network and storage I/O access across multiple application servers.