Problem

Appliance system backup either from the Webmin interface or via the command line through /usr/local/bin/system-backup.sh gets only a subset of required files when it runs out of space in /opt/backups. The issue is that it didn't inform the user of an error.

Resolution

Update the appliance backup package to at least version 7.3.1-1

$ yum install appliance-system-backup

or run Update System from Webmin which updates all the system packages