Snapshot difference between backup and done over the webinterface

[Thomas Plant]

Hello.

Out of curiosity. When we do a backup of our VMs with Proxmox Backup Server, we use the snapshot method. It works perfectly. But when we create a snapshot over the web interface for a certain VM, the VM get's stuck for about 20 minutes and the snapshot creation fails with an timeout. And the VM is stuck, we have to do an 'qm unlock <VMID>' and then stop and start it.
Does PBS do another 'type' of snapshot? As already said we never had a problem making backups, but snapshotting this VM (it has 2 TB qcow disc) fails always.

Greetings,
Thomas

 

[dietmar]

Does PBS do another 'type' of snapshot?

Yes. Backup does not create a storage snapshot at all. Instead, it does snapshots by catching all writes, then backup underlying data before applying the write.