Drivers! What they need are drivers or at least don't break working ones with an update.
Old SATA I controllers are not supported, newer ones are not supported and the one I found in the middle doesn't work properly since 8.3 any more.
Since I got a bloody nose with FreeBSD, it worked 1 year, then upgrade to 8.3 and tried ~6 months to get it working again (you cannot downgrade back to 8.2 since zfs is not compatible -.-). I am back on Gentoo Linux with that box and no data loss in the zfs pools.