The basic Nagios set-up consists of a central server - the "Nagios Server" - that polls the Hadoop servcies and components in the cluster installation to check for one of the following states:
OK
Warning
Critical
Nagios writes its output to a status log, /var/nagios/status.dat. The alert
information from that file is periodically collected and displayed in Ambari Web. For more
details on Nagios architecture, see the Nagios Overview at the
nagios.org web site.
