Troubleshooting

Note :

• Nagios gives you details about which service is down 
• Based on which service is down you troubleshoot based using below methods

Service Running

• Run this command "sudo service [service-name] status"
• if the response is "[service-name] is not running". Just restart the server by running " sudo service [service-name] restart"

Disk Space Check 

• Run this command  "df -ah"
• Will list down all the file system disk usage space 
• Check for the file system who usage is more than 90%
• Then delete the files which are not required in the location where usage is more.
• Then restart the  server by running " sudo service [service-name] restart"

Cassandra  PID file dead 

• Run this command "sudo service cassandra status" and you get response as "Output:Cassandra dead but pid file exists."
• Remove the dead pid file by running the command "rm /var/run/cassandra/cassandra.pid"