How to turn an old PC into a home server

What a home server can do

• File storage and sharing for the whole house, like a private Dropbox.
• Photo backup from everyone's phones with apps like Immich.
• Media streaming with Jellyfin or Plex, so your movies and music play on any TV or phone.
• Network-wide ad blocking with Pi-hole or AdGuard Home.
• Smart-home control with Home Assistant.
• Backups of the other computers in the house.
• Learning: Linux, Docker, networking, and virtual machines, on hardware you can't break anything important on.

You don't need all of these. Most people start with one, usually file storage or ad blocking, and add more as they go.

Which old PC works best

Almost any 64-bit PC from the last 12 years or so will do. What matters most for a machine that runs all day:

• Power use. This is the running cost. A mini PC idles around 12 to 15 watts, about $20 a year at Kansas rates. An older desktop tower might idle at 40 to 60 watts, or $55 to $85 a year. An old rack server can cost $150 to $275 or more.
• Memory. 4 GB runs a few simple services. 8 GB is comfortable. 16 GB or more if you'll run virtual machines.
• An SSD for the system. A small SSD for the operating system makes everything snappier. Old hard drives are fine for storing files.
• Drive bays. If storage is the main job, a desktop tower with room for two or three big drives is handy. Laptops and mini PCs usually hold one or two.
• Wired Ethernet. A server should plug into your router or switch, not use Wi-Fi.

Even an old Mac can do it. I've run Proxmox on a 2013 Mac Pro, though it draws a lot more power than a mini PC.

Old laptops are underrated for this. They sip power, and the battery keeps them running through short power blips. Leave the lid open or set it to do nothing when closed, and keep it somewhere with airflow.

Which software to install

I've run CasaOS and ZimaOS, and they're the gentlest way in: install, open a web page, and click to add apps like Jellyfin or a file server. (Here's how CasaOS and ZimaOS compare.) When you want more control, most people graduate to Docker on Ubuntu or Debian, or to Proxmox, which is what I run now.

Proxmox is worth the learning curve if you like to experiment. It lets one PC run many separate systems at once, and you can take a snapshot before a risky change and roll back if it goes wrong. It's how I try out new Linux versions and apps without touching anything that matters.

Setting it up

1. Wipe the old PC. If it has anything personal on it, back that up first. The install erases the drive.
2. Check the BIOS. Set Restore on AC power loss (sometimes called "After power loss") to Power on, so the server comes back by itself after an outage. While you're there, turn on virtualization (VT-x or AMD-V) if you plan to use Proxmox.
3. Install the software from a USB stick, the same way you'd install Linux. Most server systems don't need a monitor afterward. You manage them from a web browser on another computer.
4. Give it a fixed address. In your router's settings, reserve an IP address for the server (often called a DHCP reservation) so it doesn't change and your bookmarks keep working.
5. Turn on automatic security updates, or set a monthly reminder to install them.
6. Consider a small UPS (battery backup) for a desktop. Sudden power loss is the most common way home servers get corrupted.

Reaching it from outside your house

Don't open ports on your router to reach your server from the internet. That exposes it to constant scanning and attacks.

Use a private VPN instead. Tailscale is the easiest. It's free for personal use, and once it's installed on the server and your phone or laptop, you can reach the server from anywhere as if you were home. I use it on my Proxmox cluster, set up as a "subnet router" so one install gives me access to everything on my home network. WireGuard is a good do-it-yourself alternative.

Backups: don't skip this

Once family photos live on your server, it needs a backup like any other computer. Mirroring two drives (RAID) protects against one drive dying, but it's not a backup. It won't save you from deleting the wrong folder, ransomware, or a fire.

The usual rule is 3-2-1: three copies of anything important, on two different kinds of storage, with one somewhere other than your house. An external USB drive plus a cloud backup service covers it. My backup guide covers the basics for PCs.

What my setup looks like

My homelab is a three-node Proxmox cluster plugged into a UniFi switch, and I use mini PCs for my homelab servers and network services. The three nodes share the load, and I can update or reboot one at a time without taking everything down. Tailscale handles remote access. Network services, self-hosted apps, and whatever Linux version I'm trying out that week all run as virtual machines and containers on it.

You don't need three machines to start. One old PC and an afternoon is plenty. If you catch the bug, add a second mini PC later. For current prices on used mini PCs, memory, and drives, I keep price trackers on my personal site, including one for small Proxmox-ready PCs and one for hard drives and SSDs.