Disabling NCQ with:
echo 1 > /sys/block/sda/device/queue_depth
echo 1 > /sys/block/sdb/device/queue_depth
makes mdraid creation and syncing with no errors (so far).
Wondering how to make this change permanent without need to recompile the kernel (like in this answer).
Posibility to change some other kernel parameters permanently (kernel log buffer, cpufreq governor, libata parameters) will be much appreciated.