Device on one cable — speed impact
There are many debates about how much a slow device can impact the performance of a faster device on the same cable. There is an effect, but the debate is confused by the blurring of two quite different causes, called here "Lowest speed" and "One operation at a time".
The Serial ATA standard has supported native command queueing since its first release, but it is an optional feature for both host-adapters and target-devices. Many less expensive PC motherboards do not support NCQ. Many SATA/II hard drives sold today support NCQ, while no removable (CD/DVD) drives do because the ATAPI command set used to control them prohibits queued operations.
August 3, 2011