Running updates can cause any sysadmin to break out in a cold sweat, especially when that service you and your users rely stops working. Today I ran my updates on my CentOS 5.x server and noticed that the rrdtool package had been updated. Like any good sysadmin I keep a log of the updates I install on each server so that I know what has been installed and so I know services to check later to make sure everything is still working.
Since I have spent so much time with my Cacti monitoring system I knew that it was dependant upon the rrdtool. When I logged into my Cacti everything appeared normal until I looked at my graphs. All of the text on the graphs were missing. I still had the pretty colors and the graphs, but there were no numbers, labels, headers, etc. After searching around I found the solution in the Cacti forums. The problem was related Cacti not being able to pass the default font variable to the specific version of the rrdtool 1.2.28. So you have to put the path to the rrdtool font file in the Paths section under settings as well as the Font File fields under the Visual field.
The font path on my CentOS system is: /usr/share/rrdtool/fonts/DejaVuSansMono-Roman.ttf
Having a monitoring system like Cacti paired with Nagios can really help you and your IT department implement proactive measures to maintain your network. If you would like assistance in putting together your own monitoring setup with Cacti and Nagios please contact me.