How to Back Up and Restore LXD Instances?

LXD's Two Main Backup Strategies

LXD provides two powerful and flexible backup and recovery mechanisms suitable for different scenarios:

• Snapshots: Used for quick, instant, in-place backups and restores. Ideal for creating a "safety net" before performing risky operations.
• Export/Import: Used to create complete, portable backup files. Suitable for offline storage, archiving, or migrating instances between different hosts.

Method 1: Using Snapshots for Quick Rollbacks

A snapshot is a complete record of an instance's state at a specific point in time (including the filesystem and configuration). It is extremely fast to create and (when using ZFS or Btrfs) takes up almost no additional space.

1. Create a Snapshot

Create a snapshot named `before-update` for an instance called `my-web-server`:

lxc snapshot my-web-server before-update

2. View Snapshots

You can use the `lxc info` command to see all snapshots for an instance:

lxc info my-web-server

3. Restore from a Snapshot

If an update operation fails, you can instantly restore the instance to the state of the snapshot:

lxc restore my-web-server before-update

Note: The restore operation will overwrite all current changes in the instance.

4. Delete a Snapshot

Once you are sure a snapshot is no longer needed, you can delete it to free up resources:

lxc delete my-web-server/before-update

Method 2: Export/Import for Full Backups and Migration

This method packages your instance (or one of its snapshots) into a single compressed `.tar.gz` file, which you can download, store anywhere, or import on another LXD host.

1. Create a Snapshot (Recommended)

To ensure data consistency, the best practice is to first create a snapshot of a running instance and then export that snapshot.

lxc snapshot my-web-server backup-snap

2. Export the Instance

Export the snapshot you just created into a file named `web-server-backup.tar.gz`:

lxc export my-web-server/backup-snap web-server-backup.tar.gz

Tip: You can also export a running instance directly (`lxc export my-web-server ...`), but this may lead to data inconsistency. Exporting a snapshot is the safer choice.

3. Import the Instance

You can import the backup file as a brand new instance. This can be done on the same host (for cloning) or on another host (for migration).

# Run on the target host
lxc import web-server-backup.tar.gz my-restored-server

Once the command completes, a new instance named `my-restored-server` will be created with the exact same state as when it was backed up.

Summary: Which Method to Choose?