linux で NCQ が有効かどうかを確認する方法

dmesg の (depth \d+/ の数字が 0 じゃなければ NCQ 有効。

Linux NCQ (SATA native command queueing) support is enabled automatically, if your SATA drive supports it. At boot, you will see a line in dmesg (or kernel log) like

ata2.00: ATA-7, max UDMA/133, 321672960 sectors: LBA48 NCQ (depth 31/32)

If the line containing the sector count and maximum UDMA speed does not mention NCQ, your drive does not support it.
If NCQ is present but disabled, you may see "depth 0":

ata2.00: ATA-7, max UDMA/133, 321672960 sectors: LBA48 NCQ (depth 0/32)

http://linux-ata.org/faq.html

ドライバ的には AHCI 対応のハードウェアにいっとけみたいな話なのかな (参考: http://linux-ata.org/driver-status.html)