Right now I’m creating a nightly restic snapshot of my server on borgbase and on some spare drives, and keeping the snapshots forever. There’s a ton of daily churn in my data though, between databases and logs and other files that don’t constitute ‘real data’ but might be needed to restore the app.
Most of what I would use proxmox for doesn’t even require backing up. A copy of each VM when it is setup and possibly update that every few years would be plenty.
I think you can export the whole VM? Using virtualbox currently which has import/export appliance. Doing that on an infrequent basis is pretty much what I would need.
Proxmox has backup stuff for VMs and containers which uses whatever storage youbadd (local, NFS,), and has retention settings. iirc those will always be full backups. for incremental and more, proxmox backup server (PBS VM using backupNAS as destination for me)