backup -p. How does the "-p" switch work?


I’m testing out vertical backup.

Let’s say I want to preserve my ESXi VM Snapshots. Obviously the -p switch is used to do this. However, what if the disks of my VMs change during the backup process? Is it safe to run “backup -p” on a running VM that will likely have changes to disk made while the backup is running


The -p switch means ‘do not create snapshots’. Therefore, it will try to read the disk file without creating a snapshot first. If there isn’t a snapshot, then the disk file will not be readable and it will bail out with an error. Yes, it is safe to run “backup -p” as long as there is one snapshot and that snapshot doesn’t get deleted during the backup. This works because all disk changes go to the delta disk file when there are at least one snapshot. And Vertical Backup only reads from the base disk file which does not change.