One embodiment of the present invention sets forth a technique for
reducing the latency associated with media protection notification for
serial interface mass storage devices, such as serial AT attachment
(SATA) hard disk drives. A new link layer primitive, referred to as
hold-emergency (HOLDE), incorporates the flow-control behavior of the
existing HOLD command, with the additional new action of notifying the
hard disk drive to take emergency steps to prepare for impact. The HOLDE
link layer primitive operates in conjunction with the existing
hold-acknowledge (HOLDA) primitive and is semantically similar to the
existing HOLD primitive. The HOLDE mechanism is preferably implemented
directly in hardware in the SATA link layer state machines within the
host and the hard disk drive.