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Snapshots and Backups

Proxmox gives you two safety nets that sound alike and do different jobs. Mixing them up is the classic beginner mistake, so let's separate them cleanly.

Snapshots: rewind buttons

A snapshot freezes a VM's disk (and optionally its RAM) at a moment in time. You can roll back to it later — the VM returns to exactly that state. It's a rewind button.

Snapshots are for short-term experiments: about to upgrade the guest OS? Snapshot first. About to edit a config you might break? Snapshot first. If it goes wrong, roll back in seconds.

What snapshots are not: protection against anything happening to the host. They live on the same disk as the VM. Dead disk, dead snapshots.

qm snapshot 100 before-upgrade     # take one
qm listsnapshot 100                # list them
qm rollback 100 before-upgrade     # rewind to it
qm delsnapshot 100 before-upgrade  # delete it when you're sure

Honestly labeled: all four commands verified against the official qm(1) man page; not executed in this build environment.

Don't hoard snapshots — each one slows the disk slightly and eats space. Take, test, delete.

Backups: lifeboats

A backup (vzdump) copies the whole guest — disk, config, everything — into a compressed archive file on backup storage. It's a lifeboat: if the host dies, you restore onto another machine.

Backups are for disasters and the long term: nightly or weekly, kept on different hardware (remember that NFS share from Storage).

Scheduling backups

Don't run backups by hand. From the docs — the UI path:

  1. Datacenter → Backup → Add.
  2. Pick the storage (your NFS share, ideally), the schedule (e.g. weekly, Sunday 02:00), which guests (or "all"), the mode, and how many to keep.

Proxmox then runs them on schedule, and each appears as a task in the bottom panel. Check the task log the first few mornings until you trust it.

Backup modes, plainly:

  • Snapshot mode (default for running VMs): brief freeze-and-copy. The VM keeps running; you barely notice.
  • Stop mode: shuts the VM down, copies, starts it back up. Safest copy, but there's downtime.
  • Suspend mode: pauses the VM during the copy. A middle ground, rarely the right answer at home.

Retention

"Keep last 3" is a fine home default: three restore points, oldest deleted automatically. More copies won't save you from a failure you discover on day four — that's what off-site or longer retention is for, which is beyond this guide's scope.

The one idea to keep

Snapshots are rewind buttons for experiments — fast, local, temporary. Backups are lifeboats for disasters — scheduled, off-host, kept. You need both, for different reasons. Next: stop building machines by hand, in Templates and Cloning.