A snapshot is not a backup: where the difference lies and why it matters
A snapshot lives on the same disk. If the disk goes, the snapshot goes with it. A backup sits somewhere else, and that is the only real difference.
AtlasPVE ·
This entry answers
- proxmox snapshot vs backup
- can a snapshot replace a backup
- how long should a proxmox snapshot be kept
- do snapshots fill the disk
- rolling back a snapshot
Taking a snapshot is easy, fast and gives an instant way back. Those three qualities are what lead people to mistake it for a backup. Yet there is a single, decisive difference between them.
Where each one lives
A snapshot lives on top of the machine's disk. Same storage, same pool, most often the same physical drives. A backup is copied and written somewhere else. That difference decides everything: if the drive fails, the pool degrades beyond repair or the storage is wiped, the snapshot goes with it. The backup does not, because it is not there.
What a snapshot is good for
A snapshot is taken before a risky step: an update, a configuration change, an experiment. If things go wrong you are back within minutes. That is a real and valuable capability, only its scope is narrow: it does not protect against whatever happens to its own disk.
How long to keep one
A snapshot was not designed to be permanent. Because it holds every change made since it was taken, it grows over time, and a long standing snapshot is the most common reason a storage fills up. The rule is simple: once the risky step is over and the result is good, the snapshot goes. A snapshot left for weeks is no longer protection, it is weight.
The right arrangement
The two do not replace each other, they work together. The snapshot is for a short term way back, the backup is the long term guarantee. And a backup has only one real test: have you ever tried restoring from it? An untested backup does not count as a backup.
Sources
Proxmox's own documentation. In English, and it has the final word on this subject.