When you upgrade ZENworks Service Desk 7.5 or ZENworks Service Desk 8.0 to ZENworks Service Desk 8.1 via Online Update, then Ganglia Monitoring might not be accessible.
Workaround: In Ganglia Monitoring Configuration in ZENworks Service Desk 8.1 Appliance console, manually enable the Ganglia Monitoring.
For more information, see Ganglia Configuration.