Getting started · 9 of 9
Written 24 Aug 2026. This is a how-to, not a product card.
What a VM is, and when you don't need one
A pretend computer inside the old PC. Useful later, when you want to try something without breaking Pi-hole. You don't need one this weekend.
The old PC is already a computer. You can SSH in. Maybe ads are blocked. Maybe photos live in a share. A VM is not the next install. It is an idea for later.
What this is
A virtual machine, a VM, is a pretend computer running inside this one. It has its own OS, its own name, its own files. If you break the pretend one, the real computer (and Pi-hole, and the share) keep running.
You already did the real work. SSH from the couch works. Maybe Pi-hole is answering names. Maybe a share holds photos. None of that needs a pretend computer.
Why people want one
A second OS to try. A messy app in a box you can delete. Experiments kept off the house services. Those are real jobs. They are later jobs.
Why you wait
An old OptiPlex with 8 GB of memory is already busy if Pi-hole and a share are on it. Each VM wants its own slice of memory. Day-one VMs are how the house internet dies at dinner.
When it is time
You have a reason to try something that could break this computer, and it has spare memory. 16 GB is a better starting point for VMs. Check the chip first: see if the computer can run a pretend computer. Until then, skip it.
Two later paths
| Path | What that means |
|---|---|
| Stay on Debian or Ubuntu | The OS already on this computer. Later you can add one VM with virt-manager, or just keep using the real machine. Default: keep using the real machine. |
| Reinstall as Proxmox | Only if the whole job is many pretend computers. That is a fresh install, not a package on top of Pi-hole. See what OS to put on it. |
Don't dual-purpose a Pi-hole box as a hypervisor this month.
You don't buy a second computer for this. You don't buy an N100 to have a hypervisor.
What next
Leave the computer alone. If you actually want to spend, used office gear is later. A tiny computer you can leave on is later too.
Skip
- Skip installing Proxmox tonight.
- Skip Kubernetes.
- Skip Docker Swarm.
- Skip nested virtualization.
- Skip GPU passthrough.
- Skip buying RAM before you have a reason.
- Skip wiping the Pi-hole box to "do it right."
Sources
A plain explainer. Later reading, official pages only: Debian wiki: system virtualization. Proxmox VE Administration Guide. For the OS choice, see what OS to put on it. For the backup you already have, see a backup of the house folder. For the house ad block, see the first useful thing.