I was asked at the meeting about converting an existing setup and update from device names in fstab to duid.

It is easier than I expected...

sudo disklabel sd0 | awk '/duid:/{print $2}' ef02643ce3b571a4

That's your DUID for the device /dev/sd0.

In fstab replace: /dev/sd0a with ef02643ce3b571a4.a

The pattern from this should be obvious.

Maybe try with a swap slice first to see if it works for you.

The advantage of swapping to DUID's is that no matter where you put that drive in the device chain it will be recognized as the particular disk and mounted accordingly. Also solves an issue if the order of disk detection is somehow not consistently ordered on detected.