Does Apple support Native Command Queing (NCQ) in hard drives?

Yes if it's enabled and supported on the SATA drive. You might look at benchmarks at Storage Review. I recall reports of a while back that indicated that NCQ resulted in some lower performance than when disabled. May no longer apply to newer model drives.

Hi,
In most cases, if NCQ is enabled with a direct connect RAID configuration (like the internal Mac Pro bays) it does not provide significant additional performance. With some hard disk models having NCQ turned on will actually provide slower overall performance. You can see this when testing the HighPoint and Areca RAID controllers in the Mac Pro as they allow the user to turn NCQ off or on.

If you read the NCQ spec, it ibdicates performance will be significantly higher with NCQ enabled. I have grown to believe that most of this is in theory, as in real use NCQ usually provides overall negative performance results with a direct connect RAID set.

The one configuration that enabling NCQ provides a slight overall performance increase is with port multiplier (PM) enclosures.

While the Apple Mac Pro will support a hard disk with NCQ turned on. I have found hard disks with NCQ enabled will not provide measurably higher performance results than if the HD has NCQ turned off while mounted in the Apple Mac Pro.

Have fun!

There were G5s, pre-pci express / dual/quad core, where NCQ was not supported, and disk drives didn't work.

NCQ was part of a set of standards, implimented "willy nilly" by different vendors as part of SATA 2.5 features.

The Mac Pro has always had full support for SATA II features, though as pointed out by, there may not be any real world benefit.

SCSI used a different mechanism for cache and command queueing, where it mattered in deferred I/O and deeper queue depth than SATA, and benefited servers very noticably.

So "some" and "certain" seems like... mischaracterization, I think.