I made a little ‘Ghost’ server, a Pi that sits dormant in my basement with its ethernet disabled. Randomly, once every few weeks the system wakes up, connects to the primary server and syncs all the updates to its local hard drive. Once it’s done it turns the hard drive and ethernet back off and goes black until next month. This is my extra ridiculous, worst case scenario backup solution. There are push buttons on the Pi that I can press to activate the ethernet for servicing the host before taking it back offline again.

In the video you can see a short press toggles the ethernet, but a long press will turn on ethernet and trigger a manual backup before the ethernet turns off again.