As far as I know, the numbers in between define the queue depth of
commands sent to the disks.

It's a matter of whether you want the disk(s) firmware to manage
sorting & executing the commands (when the queue is > 1) or not.

	Well, what I am wondering is whether or not some value higher than 1
might produce better performance without risking the error.

all cases, as far as I know, the kernel does the sorting before
sending the commands to the disk(s). So if you notice better
performance (when the array is stable) with the queue=1, then keep it
that way.

	Definitely not, it seems.  At least for the resync, turning off NCQ
dropped the read rate from 35 MBps per drive to 25 MBps per drive.