This alert is triggered if the various individual DataNode processes cannot be
established to be up and listening on the network for the configured critical threshold,
given in seconds. It uses the Nagios check_tcp plugin.
The DataNodes are down or not responding
The DataNodes are not down but are not listening to the correct network port/address
The Nagios server cannot connect to one or more DataNodes
Check for dead DataNodes in the Services list.
Check for any errors in the DataNode logs (
/var/log/hadoop/hdfs) and restart the DataNode, if necessaryRun the
netstat-tuplpncommand to check if the DataNode process is bound to the correct network portUse
pingto check the network connection between the Nagios server and the DataNode
