Snapshots

QB-SNAP-007 Rev 1.0 – June 2026

A snapshot is a saved point-in-time state of a VM's disk. Take one before a risky change, such as a major update, an experiment, or a configuration overhaul, and you can roll back to it in seconds if things go wrong.

How Snapshots Work #

QuantaBox snapshots are stored inside the disk image using QCOW2's built-in snapshot support (via qemu-img snapshot). Each snapshot records the disk state at the moment it was taken. Because they live in the image, snapshots only work with QCOW2 and QVD disks, not Raw, VMDK, or VDI. See Storage and Disks.

Take snapshots while the VM is stopped for a clean, consistent disk state. Snapshotting a running guest captures only the disk, not RAM, so the guest may see it as an unexpected power loss when restored.

Creating a Snapshot #

GUI: Select the VM, open the Snapshots tab, enter a name, and click Take Snapshot.

CLI:

quantabox snapshot create my-ubuntu before-update

Give snapshots descriptive names (before-update, clean-install, pre-experiment) so their purpose is obvious later.

Listing Snapshots #

GUI: The Snapshots tab lists each snapshot with its name, size, and timestamp.

CLI:

quantabox snapshot list my-ubuntu

Output shows each snapshot's tag, size, and creation date/time.

Restoring a Snapshot #

Restoring rolls the disk back to the saved state.

GUI: Open the Snapshots tab, choose a snapshot, and click Restore (confirm the prompt).

CLI:

quantabox snapshot restore my-ubuntu before-update
Warning: Restoring discards all changes made since that snapshot was taken. If the current state matters, take a new snapshot before restoring.

Deleting a Snapshot #

When you no longer need a snapshot, delete it to reclaim space.

GUI: Open the Snapshots tab, choose a snapshot, and click Delete (confirm).

CLI:

quantabox snapshot delete my-ubuntu old-snapshot

Deleting a snapshot does not affect the current disk state; it only removes that saved point.

Snapshots vs. Backups vs. Clones #

These three are related but distinct:

FeatureScopeLives WhereUse It To
SnapshotOne disk's stateInside the disk imageRoll back quickly on the same machine.
BackupFull disk copySeparate .qvbk fileRecover after disk loss or corruption. See Backup, Export and Import.
CloneWhole VM copyA new VMDuplicate a VM to diverge from it. See Creating Virtual Machines.

Snapshots are the fastest safety net but they depend on the original disk. For protection against disk loss, use a backup or export.

Best Practices #

  • Snapshot before OS updates, driver changes, or risky experiments.
  • Keep snapshot chains short. Many stacked snapshots fragment the image and slow it down. Delete snapshots you no longer need.
  • For long-term safekeeping, prefer a backup or encrypted export.

Next Steps #

Continue to Post-Quantum Encryption to protect your VM disks at rest.

← Networking Post-Quantum Encryption →