How do I enable NCQ? How do I disable NCQ? How do I know if NCQ is enabled? Why are only 31 tags used, rather than 32?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) likeata2.00:…
Also, note that ZFS spawns a lot of threads for concurrent IO. So, enable NCQ (check queue length in /sys/block/<drive>/queue/nr_requests) on the drives if it is not set already. Invest into some SSD drive(s) as the L2 cache, which will speed up random IO ops tremendously.