Hey OMV community
My Setup
I built my first home NAS this year after inheriting an "old" laptop and trying to think of useful things to do with it. I also had a handful of old 2.5" drives, and always wanted to build a home NAS.
In installed OMV5 and put 4 drives into a USB enclosure and built a unionFS, and am sharing over the home network with SMB, with openVPN for remote access.
Using docker/portainer, I'm running qbittorrent, plex, pihole, and cloudcommander.
My Dilemma
It's been fun getting everything set up but I realize now I wish I'd setup my UnionFS with a RAID redundancy in case one of these dusty old drives fails.
Should I be worried about bottleneck (since I'm using external drives connected with USB)?
When I decide to move to a setup with RAID backup, how do I go about it, given there is now data on the drives?
I'm kind of scared of mass file copy/move operations as I've heard that's what can cause HDD's to fail, and my rig is riddled with older units 
Don't worry, the data on the server today is not crucial data, but at some point it would be nice to view the server as a somewhat higher level of safety for data storage than what it is now: a fun home kit with an expiry date...
Candy...
I also happened upon two LSI RAID controller cards which I can't use with my current setup (can you believe there are no open PCIe slots in this old laptop 
) - any advice on sourcing a suitable (budget friendly) machine/motherboard, and is hardware RAID preferred for OMV Home NAS, or is software RAID just as good?
I'd love to hear some thoughts - thanks for reading