How do you prevent this? In fact, it is very simple. I have tested it here with a 10TB VM.
Normally the VM would take about 48h to save. Even if there are no changes. With a little trick this can be prevented.
Before a reboot of the proxmoxserver, e.g. for updates, simply put the desired VM into sleep mode (Hibernate). This will continue to run the VM normally after a host reboot. And the backup here took only 11 seconds for 3GB change.
Tested on PVE 8.0.4, PBS 3.0-1
Normally the VM would take about 48h to save. Even if there are no changes. With a little trick this can be prevented.
Before a reboot of the proxmoxserver, e.g. for updates, simply put the desired VM into sleep mode (Hibernate). This will continue to run the VM normally after a host reboot. And the backup here took only 11 seconds for 3GB change.
Tested on PVE 8.0.4, PBS 3.0-1