I call this nonsense host ‘Ghost’, for me it’s similar to a tape backup solution. Fairly simple concept, it’s an old Pi1 + external mechanical drive that sits dormant with its ethernet off. Once a month, at a random time and random date it enables the ethernet, spins up the drive and pulls data from the main server to update its drive then goes black until next month. The only way to check or maintain the pi is a push button that toggles the ethernet interface. I slapped it together with some scrap wood, spare hardware and screwed it to a 2x4 in a dark corner of my basement. It’s my 5th string backup, the ultimate insurance policy because I’m mental.