A system including a multi-port storage device (e.g., a disk drive) and at least two users, each user coupled to a port of the storage device by a serial link. The storage device has an operational portion and an interface (including arbitration circuitry) between its ports and the operational portion. In response to a set of competing priority bids from the users, the arbitration circuitry grants one bid (including by sending an acknowledgement to the successful bidder) and preferably holds each non-granted competing bid without sending any notification to the unsuccessful bidder until the successful bidder sends a deselect signal. The system can be a RAID system including at least two disk drives and at least two controllers, where at least one drive is a multi-port device shared by at least two of the controllers. Preferably, each priority bid and deselect signal is a primitive code (e.g., an ordered sequence of a 10-bit control character and three 10-bit data characters in SATA format). Other aspects of the invention are multi-port storage devices and users for use in such a system.