I have a server with a RAID-1 array, that makes daily, weekly, and monthly read only btrfs snapshots. The whole thing (sans snapshots) is sync’d with syncthing to two rPi’s in two different geographic locations.
I know neither raid nor syncthing are “real” backup solutions, but with so many copies of the files living in so many locations (in addition to my phone, laptop, etc.) I’m reasonably confident its a decent solution.
I really liked the client but HTML emails are a real pain in the ass.