A full Proxmox cluster rebuild from scratch takes somewhere between a weekend and a week, depending on how much of your config lives in Git versus your head. The VMs and LXCs themselves, the ones with actual state in them, those are the things you can't reconstruct from memory. Proxmox Backup Server (PBS) exists specifically for this problem: deduplicated, incremental backups of your entire virtualization layer, with verification built in.
If you're running a multi-node Proxmox cluster and your backup strategy is still "I'll just snapshot it manually before I do anything scary," this is the upgrade path. PBS slots into an existing cluster with surprisingly little friction, but the authentication model and a few operational quirks will trip you up if you don't know they're coming.
Why Not Just Use vzdump to NFS?
The built-in vzdump tool works. You can schedule backups to an NFS share and call it a day. I've seen plenty of homelabs run this way for years. The problem is what happens at scale.
With vzdump to a plain NFS target, every backup is a full copy. A 50 GB VM backed up daily for 30 days is 1.5 TB of storage, most of it identical data. PBS changes this fundamentally. It chunks the data, deduplicates across all backups (and across all VMs), and only transfers the changed chunks on subsequent runs. That 1.5 TB becomes something closer to 80-120 GB depending on churn rate.
