Proxmox is an easy-to-setup virtualization platform that offers a rich set of features to help you in building your ideal home lab. If you have multiple devices running Proxmox in your computing environment, you can use the clustering facility to access all the nodes from a single interface. It’s also quite simple to set up, though there are a couple of issues you need to be aware of before you attempt this process.

What you’ll need

While Promox lets you configure a cluster with two nodes, you should use an odd number of devices for a cluster. We’ve used two Proxmox machines for this guide, but you should stick to a 3-node setup if you want a high-availability cluster. Without going into Qdisk shenanigans, a cluster with just two nodes will become inaccessible the moment either device goes offline. But that’s a tutorial for another time.

Another problem worth highlighting is that the secondary nodes, or rather the ones you’ll add after creating the cluster on the primary node, shouldn’t possess any guest VMs or containers. Even if the names and IDs of the virtual guests are different, Proxmox will throw an error when you try to add a node without deleting them. This may not seem like a big deal for a newly created node, but if you’ve been using the Proxmox machine for a while, you’ll have to go through some extra steps to back up and restore the virtual machines/containers on the non-primary Proxmox machines.

(Optional) Backing up and deleting the virtual guests

If you’re fine with deleting the virtual guests on your Proxmox nodes, feel free to skip to the next section. But for those who don’t want to lose precious data when building the cluster, you can follow these steps to create backups of your VMs and containers.

1. Inside the Proxmox web UI of your secondary node, select the virtual machine or container you wish to back up.
2. Navigate to the Backup tab and pick the Backup Now option.
3. Hit the Backup button and wait for the Task viewer utility to display the TASK OK message.
4. With the contents of the virtual machine saved as a .zst file, click on the More drop-down menu and hit Remove.
5. Type the VM ID inside the confirmation pop-up box and press the Remove button.
6. Repeat this process for all containers and virtual machines.

Creating the cluster

Once you’ve powered all the Proxmox systems, it’s time to log into the web interface of the machine you’re planning to use as the main node for the cluster.

1. Select the Datacenter tab on your primary Proxmox node.
2. Head to the Cluster submenu and hit the Create Cluster button.
3. Give a Name to your Proxmox cluster and press Create.
4. Click on Join Information and copy the contents of the Information field to your clipboard.
5. With the cluster up and running, fire up a new tab in your web browser and log into the Proxmox UI of your secondary nodes.
6. Navigate to the Datacenter tab, select the Cluster sub-menu, and pick Join Cluster.
7. Paste the encoded key you copied earlier into the Information field.
8. Enter the password of the primary Proxmox node into the Password field.
9. Select the IP address of the secondary node inside the Link 0 option of the Cluster Network field before tapping Join Cluster.

(Optional) Restoring the deleted virtual guests

If you backed up the virtual guests before adding the node to the cluster, you can restore them by following these steps:

1. Select the local (node_name) directory of your secondary node.
2. Click on Backups and hit Restore after selecting the dump file you created earlier.
3. Repeat this process for each container and virtual machine you want to use on your cluster.

Converting your Proxmox nodes into a cluster

Assuming you followed all the steps correctly, the secondary node(s) will no longer be accessible from their IP addresses. Instead, the nodes (and all the restored virtual guests) will appear inside the Proxmox UI of the primary cluster machine. But if setting up a cluster isn’t your thing, there are a lot of cool projects you can pull off using Proxmox, including a stress-free Hackintosh machine, a full-fledged gaming server, and a makeshift NAS.