Does Zenoss use severity set by the Nagios Plugin return?
Yes. Per Chet Luther: You can use the 1/2 exit codes from Nagios plugins to drive the severity of the resulting Zenoss event. The way it works it that if the plugin exits with a code of 1 (WARNING) Zenoss will set the severity of the event to whatever you selected for severity when you created the data source. If the plugin exits with a code of 2 (CRITICAL) Zenoss will use the next highest severity. An exit code of 3 (unknown) will give the same severity as the data source. So if you choose Warning as the severity in the data source, and the plugin exits with a code of 2, the event will actually have a severity of Error.