Snapshots

DNA-Nexus can create Btrfs filesystem snapshots for configured snapshot volumes. A snapshot stores the state of a selected Btrfs source at a specific moment. Snapshots are useful when you need a fast rollback point for stored NAS data.

The default protected volume is usually the DNA-Nexus data volume at /srv/pqnas/data. Administrators can also add separate Btrfs storage pools, such as /srv/pqnas/pools/pool2, to snapshot protection.

Snapshot Manager showing protected volumes and available snapshots — Snapshot Manager with protected volumes and available snapshots

What snapshots include

Snapshots are created from the configured source subvolume or Btrfs source path. In the default configuration, this is:

/srv/pqnas/data

The snapshots themselves are stored under that volume's configured snapshot root. For the default data volume, this is usually:

/srv/pqnas/.snapshots/data

In the default configuration, snapshots cover data stored under /srv/pqnas/data. This includes user data, workspaces, avatars and application data files located under that data root.

Snapshots do not automatically include the whole Linux operating system, server binaries, installed application packages, static runtime files or configuration files stored outside the configured Btrfs source.

Protected volumes and pools

Snapshot protection is configured per volume. Snapshot Manager shows the configured protected volumes on the left. Selecting a volume shows the snapshots available for that volume.

Additional Btrfs storage pools can be added from Administrator settings → Snapshots. For example, a pool mounted at:

/srv/pqnas/pools/pool2

normally stores its snapshots inside the pool:

/srv/pqnas/pools/pool2/.snapshots

Keeping the snapshot root inside the same pool is important because Btrfs snapshots must stay on the same Btrfs filesystem as the source.

Requirements

Snapshot support requires Btrfs. Non-Btrfs backends, such as Ext4, cannot use Btrfs snapshot features.

The DNA-Nexus server must also be able to run the required Btrfs commands with sufficient privileges. If snapshot verification or restore actions are disabled, check the Snapshot Manager sudo setup instructions.

Creating a manual snapshot

To create a snapshot manually, select the protected volume in Snapshot Manager and click Create snapshot now.

Confirmation dialog for creating a snapshot immediately — Creating a snapshot immediately

A confirmation dialog is shown with the snapshot name. After confirming, the snapshot is created immediately under that volume's snapshot root.

Restoring a snapshot

To restore an older snapshot, select the protected volume, select the desired snapshot from the list based on its timestamp, and click Restore.

Confirmation dialog for restoring a selected snapshot — Restoring a selected snapshot

A confirmation prompt is shown before the restore begins. After you accept it, the restore process starts.

During snapshot restore, the server software restarts automatically. In most cases, users will only notice that the service is unavailable for a short time.

Important notes

Important: Restoring a snapshot returns the selected volume to the earlier state captured by that snapshot. Changes made inside that volume after the snapshot was taken may be lost.

Note: Snapshots are designed for fast rollback of configured Btrfs data volumes and Btrfs storage pools. They do not replace full system backups or separate backups of server configuration, binaries, static runtime files or operating system files.

Backup recommendation: Keep separate backups for disaster recovery. Snapshots usually live on the same storage system, so they do not protect against complete disk failure, hardware loss or site loss.