[rrd-users] scheduling RRD graph upates on a windows 2008 R2 platform

[Simon Hobson]

Brent Barr <b.barr at f5.com> wrote:

> I've gone to a system that uses a python file to generate the graphs on the fly.  Request the HTML page and it takes 5+ seconds to go get the data and generate the charts for that page.  Means I only generate charts a few times a week, and that the data is always the freshest.

That's how I do it (though I'm on GNU/Linux).
All the web pages (or more accurately, the images) are CGI scripts that generate an RRD script on the fly. Most of them take parameters, for example setting the period to day, week, etc or selecting an IP. I have the --lazy option set, so RRD will only actually generate a new graph if the data is newer than the cached image file.
With the number of potential images, it would be a huge waste of resources (not to mention needing a much much more powerful system) generating the thousands of potential graphs - most of which will be rarely (if ever) be looked at.

An example :
We have a /24 subnet at work, and I log the traffic by IP address at the border gateway. Excluding the network and broadcast addresses, that's 254 IPs, with in and out for each. I can draw a graph for any IP for a day, week, month, or year - and with or without a line to show max (significantly different from average once you start aggregating data). 254x4x2 = 2032 graphs, and that's only part of the logging I do. Most of them will not be looked at other than "once in a while" so it would be a complete waste of resources to regenerate them periodically.