Multiple disks failure

Quote from luke-ws

I tried to prepare the server for ZFS but I noticed that none of the USB ports seem to work.

You may have encountered one of OMV's restrictions. Creating RAID arrays with USB-connected drives is not allowed. This was implemented some time ago because USB drives cause numerous problems with this setup, sometimes even causing data loss, which is unacceptable to OMV.

What I just said certainly applies to mdadm arrays, though I'm not sure if it also applies to ZFS. I've never tried creating a ZFS RAID with USB drives, and I've never seen a user on the forum who has attempted to do so. It would be a bad idea anyway.

Quote from luke-ws

It seems that the problem is the mobo.

"That" would explain a LOT of things.

If there are a lot of power surges or brown outs, in your location, a good UPS is recommended. At the very minimum, a good quality surge suppression strip is needed. And, it wouldn't hurt to have an electrician check the ground at the outlet plugs. A floating ground, along with power issues can have devastating effects on CMOS circuity.