This alert is triggered if the number of down DataNodes in the cluster is greater than
the configured critical threshold. It uses the check_aggregate plugin to
aggregate the results of Data node process checks.
DataNodes are down
DataNodes are not down but are not listening to the correct network port/address
Nagios server cannot connect to one or more DataNodes
Check for dead DataNodes in Ambari Web.
Check for any errors in the DataNode logs (
/var/log/hadoop/hdfs) and restart the DataNode hosts/processesRun the
netstat-tuplpncommand to check if the DataNode process is bound to the correct network port.Use
pingto check the network connection between the Nagios server and the DataNodes.
