Linux VPS

Take and roll back Proxmox snapshots for VMs and containers

Use Proxmox snapshots before risky changes: which storage supports them, how to include RAM, roll back or delete them, and why a snapshot is not a backup.

BeginnerProxmox VE2 min read

Proxmox snapshots freeze the state of a VM or container at a point in time so you can roll back in seconds after a bad update or configuration change. They are quick and cheap, but they live on the same storage as the VM.

Before you start

  • The VM disk must be on storage that supports snapshots: LVM-thin, ZFS, Ceph RBD, or qcow2 files on directory/NFS storage. Plain LVM and raw files on directories do not (storage types).
  • The QEMU guest agent installed in VMs for consistent snapshots.

Take a Proxmox snapshot

  1. Select the VM or container and open Snapshots.
  2. Click Take Snapshot, give a name such as before-php-upgrade and a description.
  3. For VMs, tick Include RAM if you want to resume exactly where it was, running programs included. This takes longer and uses more space.
  4. Click Take Snapshot.

From the shell:

qm snapshot 105 before-php-upgrade --description "PHP 8.3 upgrade"

For containers use pct snapshot with the same arguments.

Roll back

  1. In Snapshots, select the snapshot and click Rollback.
  2. Confirm. Everything since the snapshot is lost, and the VM returns to that state.
qm rollback 105 before-php-upgrade

Delete snapshots you no longer need

Select the snapshot and click Remove, or run qm delsnapshot 105 before-php-upgrade. Old snapshots keep growing as data changes, fill thin pools and can slow disk I/O.

Warning: A snapshot is not a backup. If the disk or storage fails, the snapshot is lost with it. Keep real backups on other storage (vzdump backups).

Troubleshooting

  • Take Snapshot greyed out: the disk storage does not support snapshots, or a CD-ROM with a local ISO is attached on some setups; detach it.
  • Snapshot stuck or locked: clear a stale lock with qm unlock 105 after checking no task is running.
  • Thin pool full: delete old snapshots and watch lvs.

Frequently asked questions

How many snapshots can I keep?

Several are fine, but keep them short-lived; days, not months.

Do snapshots work while the VM runs?

Yes, there is no need to stop it.

Can I clone from a snapshot?

Yes, choose the snapshot as the source in the Clone dialog.

Next steps

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