Backups needed! Plural. Anytime someone openly admits they're screwed
if they lose certain files, it tells me at least two backup copies are
needed. In my case, the "I'm screwed" data is in a minimum of 4
independent backups including one offsite. Only one of those is raid1
and even though there are two copies of the data, I consider it one
backup, i.e. raid itself is not a backup.
I haven't tried it, but there was a recent Fedora Magazine write up
about mergerfs. I don't know if it'll complicate or help simplify the
topic under discussion.
https://fedoramagazine.org/using-mergerfs-to-increase-your-virtual-storage/
--
Chris Murphy