Last time I posted a full writeup on my lab (The before before this) there was a lot of questions on what exactly I was running at home. So here is a full writeup on everything I am running, and how you can run it too
So powering on and powering off will eventually be handled by a Powershell script I use to kick of the backups (More than just Borg goes into my offsite/offline backups) and the reason it gets powered off is that the external drive I connect to my desktop computer gets shared out, and sometimes Windows mixes the drive letters up, or the Share permissions get out of whack. I find that if the VM is on when its screwed up, Debian really doesn't like the mount and ends up causing some weird issues. So if I just leave it off until I have my ducks in a row with the backup drive, it all works perfectly. I guess there is also no point it in sitting there powered on 24/7, when I only do the backups monthly too
As for why its a dedicated VM, a few years ago I noticed I was constantly moving backup software, trying other solutions etc, which just doesn't work. If you change backup software every 6 months, you don't really have any real long term backups. So I decided Borg and the VM its installed on needs to stay very stable, so I settled on just throwing it in own VM. This way I never need to move it, migrate it, etc. Its always just there and it works