@babble_endanger @thegibson
Best case, in my opinion: Have a dedicated backup machine which pulls the data from the primary machine.
This entirely prevents the primary machine from overwriting its own backups, simply because it doesn't have the required privileges (by design).
The dedicated backup machine can even be a cheap repurposed thin client (Fujitsu Futro, Dell Wyse, ...) or something similar. No need for expensive hardware.
@toe @TheGibson Yeah I tried to do that, I bought this Awow system, and it refused to boot any distro except this one Debian I tried. It was such a pain that I gave up. I just hate spending money on hardware. If I was willing to put like $800 into a decent NUC and USB hard drive I could do it. But at that point, I'd just build a new gaming desktop and use my old one as the designated cheapo backup server.