The current SATA spec on NCQ allows a driver to send up to 32 commands to a disk drive without waiting for a previous command to complete. This allows the drive to re-order which command executes before another so it can minimize rotational and seek latencies. The best analogy is an elevator. If an elevator is on the grond floor when I call for it on the top floor and then you call for it on a middle floor, you want the elevator to stop for you on the way to my floor even though I called for it first. The drivers need to be NCQ aware because they may receive ccomand completion status in an order different than the commands were submitted -- or not at all if they have so instructed the drive. NCQ helps in an environment where a disk gets a lot of random read or wtite requests -- a true server -- as opposed to a single user machine where queue lengths are typically short anyway. Did this help? Like dual core CPUs, I think the hardare technology is a wee bit ahead of the software right now ;-)