Yes when it comes to RAID, a UPS is a must.

Linux MDADM is not resiliency against power lose. And will overwrite from master if they are not equal.

Cow system ZFS, LVM, BTRFS and similar, have separate metadata table to compare against. But even then they can be affected by write hole in the event of a powerloss.

If you are thinking it for “backup” for redundancy in case of disc error, a solution can be to use something like borg backup, and a source disk as a BTRFS file system so you can be notified if there is checksum errors.

A cheap UPS is 60€, it will work good enough.

I think Bitwarden withorganizations will fit your needs.

…connected to the internet from a public IP, no NAT and only protected by extremely complicated firewall rules. Their IT team must be in constant distress, or super defensive about their architecture haha

Why they will be protected like everyone else. With the same default rule like every other company.

I think it more odd that they haven’t sold it for a lot of money.