How to view RRD graph data

Question

What I am trying to do is get alerts when my bandwidth goes above a limit. I am using Cacti to graph my bandwidth usage, but I currently get no alerts if my usage goes up.

So I think the best way to do this would be to write a script to check the graph data every say 5 mins.

Please can someone start me on the right track to this? I have looked online how to view the graphs but it gets very complicated for me.

Answer 1

If you are already using Cacti to collect and graph your bandwidth usage, then the thold plugin will allow you to set thresholds and notification methods. http://docs.cacti.net/plugin:thold

If you are not already using Cacti, then you could instead use MRTG (with RRDTool as the backend) to collect and graph the data. MRTG has a ThreshMaxO[] directive (and corresponding directives for Inbound and Minima) to define thresholds, and a ThreshProg[] directive to define which program or script to call to do the notification.