Where are you running du -sh *? (I.e. what directory, are you definitely scanning the whole file system?) I’m sure it’s obvious, but can never hurt to check!
What does du -sh / show? (Generally, the * glob pattern in the shell will not match hidden dot-files, so is it possible they are being excluded?)
If you’re using the AIO image, backup/restore can handled for you, so no need to worry about the manual steps involved. Or if you’re using a VM, a backup can take the form of full system snapshots, so also no need to understand how data are stored. Granted it’s always helpful to know what your running, but not necessarily requisite, even for backups.
Absolutely. I actually have an upgrade already planned, but it’s just that it’s not because I can’t run VMs, it’s more that I want to run more hungry services than will fit on those resources, whatever virtualisation layers were being used. The fact that it’s an easy fix to more a VM/lxc to a new host is absolutely it, though.
Am I looking at the wrong device? Beelink EQ15 looks like it has an N150 and looks like 16GB of ram? That’s plenty for quite few VMs. I run an N100 minipc with only 8GB of RAM and about half a dozen VMs and a similar number of LXC containers. As long as you’re careful about only provisioning what each VM actually needs, it can be plenty.
Surely, if you forget it’s even running, you aren’t using it, and it doesn’t matter if it stops running? (With a couple of obvious exceptions like automated backups, etc)