Using NagiosGraph with Nagios can provide valueable information about your environment.  At times, you may want to show something on a different scale or limit the data seen within the graph.  Below are a few basics for manipulating NagiosGraph's show.cgi to customize the graph you are viewing.

Example

We use the "check_mssql_monitor 0.9.0" with our Microsoft SQL Clusters and graph the results.  My NagiosGraph "map" file graphs the CPU, IO, IDLE, and response time of checks and Nagios notes_url for the check links to the default graph.  However the scale of values typically render the IO nearly flat, yet a small change in IO can be significant.  Now we want to just generate IO graphs of each of our clusters to compare them to each other. 

Here's the default URL of the graph we are working with: 

http://nagios.domain.com/nagiosgraph/show.cgi?host=servername&service=MSSQLinfo

By manipulating the URL, we can do some handy tweaks.  Let's start with only graphing the IO.  To do that, we need to add the appropriate options to the URL.  Adding the datasource name and valuename to the URL like this:

http://nagios.domain.com/nagiosgraph/show.cgi?host=servername&service=MSSQLinfo&db=mssql_monitor,io

My favorite option is make the graph bigger!  After all, bigger is better right?  Just add the geometry option to the URL likse so:

http://nagios.domain.com/nagiosgraph/show.cgi?host=servername&service=MSSQLinfo&db=mssql_monitor,io&geom=700x200

Now we have a much larger graph and are able to see the IO response increasing during the given time period.  Next step is to figure out why!

HINT:  for the db source name, check out the default graph and look for the name immediately under the graph.  Then add the value as it appears in the legend.