Use the following instructions to validate your installation:
- Start the Nagios server. Execute the following command to start the Nagios server: - /etc/init.d/nagios start 
- Confirm the server is running - /etc/init.d/nagios status - This should return: - nagios (pid #) is running... 
- Test Nagios Services. On the Nagios host machine, execute the following command: - /usr/lib64/nagios/plugins/check_hdfs_capacity.php -h namenode_hostname -p 50070 -w 80% -c 90% - This should return: - OK: DFSUsedGB:<some#>, DFSTotalGB:<some#> 
- Test Nagios Access. - Browse to the Nagios server: - http://$nagios.server/nagios 
- Login using the Nagios admin username (nagiosadmin) and password. 
- Click on hosts to validate that all the hosts in the cluster are listed. 
- Click on services to validate all the Hadoop services are listed for each host. 
 
- Test Nagios Alerts. - Login to one of your cluster DataNodes. 
- Stop the TaskTracker service. - su -l mapred -c "/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf stop tasktracker" 
- Validate that you received an alert at the admin email address and that you have critical state showing on the console. 
- Start the TaskTracker service. - su -l mapred -c "/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start tasktracker" 
- Validate that you received an alert at the admin email address and that critical state is cleared on the console. 
 


