On 28/08/2022 10:14, Wols Lists wrote:

quoted

Currently I have no /dev/md* devices.
I have access to the old mdadm.conf file - have tried assembling with
it, with the default mdadm.conf, and with no mdadm.conf file in /etc
and /etc/mdadm.

It looks like the drives weren't partitioned :-( I think you're into 
forensics.

Whoops - my system froze while I was originally writing my reply, and I 
forgot to put this into my rewrite ...

Look up overlays in the wiki. I've never done it myself, but a fair few 
people have said the instructions worked a treat.

You're basically making the drives read-only (all writes get dumped into 
the overlay file), and then re-creating the array over the top, so you 
can test whether you got it right. If you don't, you just ditch the 
overlays and start again, if you did get it right you can recreate the 
array for real.

Cheers,
Wol