I recently moved Nagios monitoring from one server to another and ran into a couple minor issues. I wanted to point out some of the errors and the steps I took to resolve those errors on a CentOS Linux server. The biggest pain about moving Nagios for me was the fact that I use Monarch to manage the Nagios configuration files and reconfiguring Monarch was a pain because of some of the Perl modules required and the fact that CentOS still favors Perl 5.8.8 instead of Perl 5.10 which includes some of the necessary Perl modules. Anyway once I got past the Monarch issues I still had some minor problems with Nagios which are pointed out below. The errors are from the Nagios web interface.
I recently decided to do a fresh CentOS install on a web server with a minimal amount of sites on it because it seemed easier than attempting to upgrade everything. With a fresh install I figured I would be forced to get everything completed quicker. The server was upgraded from CentOS 5.1 to CentOS 5.3 and from ISPConfig 2.X to ISPConfig 3.X. One of the virtual host configurations was for a Nagios server that monitors a fairly large list of servers running various services from basic server items like CPU, Load, Disk Space, etc. all the way to complex PostgreSQL statistics and other custom items. There are numerous Perl scripts to monitor PostgreSQL including check_pg_connections.pl, check_pg_lock_status.pl, check_pg_max_xid.pl, check_pg_queries.pl, check_pg_time.pl, and check_pg_waiting_queries.pl. The scripts use the DBD-Pg Perl module to make a connection (remote or local) to PostgreSQL servers.