How do server snapshots work?

What are they?

Snapshots are an ideal short-term safety net in the event that you need to carry out potentially risky operations on your server and want a recovery point. They are provided as a safe and convenient way to revert your server state to a particular point in time.  When you make a snapshot, the server's current running state (RAM content) and disk content are frozen, and the server carries on operating.

What aren't they?

A snapshot is not a complete copy of your server and can't exist independently of your server  When a snapshot is created, any changes to your server are recorded into a new disk and RAM state.  Because only changes are being recorded, the snapshot relies on the original base disk and RAM states to operate.  This means that you can't take a snapshot, move it somewhere else, and start it up as a new server.

The up & down sides of snapshots.

The benefit of creating snapshots as a list of changes to the base VM is that creating a snapshot is extremely fast.  The downside is that there is a performance penalty for running a VM with a snapshot present, as the base disk and the snapshot image need to both be read before any disk writes can take place.  This is one of the reasons why we don't offer a snapshot tree in the Console, as incremental snapshots have increasing performance penalties.

Alternatives to snapshots.

If you need an independent - or long-term - copy of your server, use our Backup service. It can create complete server images without interrupting your server, store them safely on-site, and copy them off-site if required. To add local or remote backup to your account, mail us with the name of your server, whether you'd like weekly or monthly backups, and the number of copies you want to retain.

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