This morning we had an activity on our Nagios server, whereby we inserted new disks into the server, and rebooted the server.
The disk implementation failed, therefore we had to revoke the changes, and rebooted the server once again.
The server was up and running at 6:00 am this morning. However, after 2 hours, the nagios monitoring does not show any data (percentage of usage, etc for the services like cpu, memory, disk, etc).
What could be the problem, and how do we resolve this?