This service-level alert is triggered if either the Active NameNode or Standby NameNode are not running.
The Active, Standby or both NameNode processes are down.
The Nagios Server cannot connect to one or both NameNode hosts.
On each host running NameNode, check for any errors in the logs (
/var/log/hadoop/hdfs/) and restart the NameNode host/process using Ambari Web.On each host running NameNode, run the
netstat-tuplpncommand to check if the NameNode process is bound to the correct network port.Use
pingto check the network connection between the Nagios server and the hosts running NameNode.
