[mrtg] Zooming in to mrtg graphs

[Steve Shipway]

The first thing you needto understand is the nature of the RRD files.  Because the data is normally only polled every 5minutes, and then rolled up into 'RRA's at 5min, 30min, 2hr and 1day granularity which are preserved for <800 CDPs (combined data points), the practical upshot is that, in many cases, the details you want simply are not there.

A 1-hour graph can give you only the granularity you poll at; if you do 5min polls, then you will get only 12 data points in an hour.

Similarly, if you are looking at the weekly graph (30min CDPs) and want to zoom in on a point 4 days ago, then your 5min RRA has already expired by this point and you are already looking at the best detail available.  Zooming in to a 1-hour graph would give you the grand total of 2 points on your graph.

Having said all that, if you use the Routers2 frontend, there are 'zoom in' and 'zoom out' buttons; these will simply move between daily, weekly, monthly and yearly graphs.  If you enable RRD Archiving then you will be able to select Daily graphs for any date you have archived.  Finally, an 'Export to CSV' option is available on all graph pages to give you the data in the best available granularity.

If you modify your RRD file to store data much longer in the RRAs, and to poll at 1min granularity, then the data will be available to make the graphs you want.  However, as this would be highly customised, you'd need to define your own functions to call the RRD library with the necessary parameters to generate the graphs.  None of the available frontends (routers2, 14all, mrtg-rrd) cater for this as they deal with the standard configurations.

Steve

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From: mrtg-bounces at lists.oetiker.ch [mrtg-bounces at lists.oetiker.ch] On Behalf Of Sheikh, Nasarullah [Sheikh.Nasarullah at uk.bp.com]

Is there a way to zoom in and out on the graph area. I want to see the graphs of a particular time in details..e.g a hour graph rather than a 24 hour graph.

Is there a way that the data that generates the image can be exported to xls later.
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