You’re not worrying for nothing. Losing wall power will shut down the drives and as usb-cradle is generally slower than “proper” drive bus it’s more likely that some write operation is going on when power is lost and that’ll potentially cause data corruption. Obviously not every power outage will cause issues, but I’d say it’s a higher risk with USB-drives than with drives on a SATA/m.2 bus.
But no matter what your setup is, raid is not a backup. All kinds of things can happen which cause loss of data and you should plan accordingly. If all you have is two drives on usb-cradles I might choose to use one of them as a offline backup disk and one for ‘live’ data so that it’s more likely that at least one of the drives is functional even after power issues or whatever, but that approach has it’s own problems too.




It wasn’t for nothing, you got some learning out of the experience and a story to tell. Good luck with the new system, maybe hold upgrading that to testing for a while, there’s plenty to break and fix even without extra quirks from non-stable distribution :)
Have fun and feel free to ask for help again, I and others will be around to share what we’ve learned on our journeys.