[xymon] Question about the new rrddefinitions.cfg file

[Henrik Størner]

In <426A0EF5343CDE4CAA8565BBEDB9526F0140E8E2 at USMSG111.leinternal.com> "Stewart, Tom L." <Tom.Stewart at landsend.com> writes:

>I want to be able to handle 5 minutes of data for the rrd files for the
>entire 288 days. I used the following in the new RC1 definitions file.
>        RRA:AVERAGE:0.5:1:82944
>        RRA:AVERAGE:0.5:6:82944
>        RRA:AVERAGE:0.5:24:82944
>        RRA:AVERAGE:0.5:288:82944

First, there is no rule saying that you must have 4 RRA's. You can have
just one, if you want the same granularity of data for all of your
graphs. The option to have multiple RRA's is only for keeping data
for longer periods of time, without using "too much" space.

So 288 days with a 5 minute average ... 288 days = 288*24*60 = 414720
minutes, divide by 5 gives 82944 datapoints. So your first RRA is
correct and should cover that. If you don't want to store data any
longer than 288 days, you can delete the other three RRA's. If you 
do keep them, then you will have data for a looooong time - the last
RRA stores data for 82944 days = 227 years!

(The "288" in the last RRA means that one datapoint in this RRA
is calculated as the average of 288 of the primary - 5-minute - 
datapoints, which corresponds to 5*288 minutes = 1440 minutes = 1 day. 
Hence the RRA stores data for 82944 days).


>After only a couple of days, it looks like I am only getting 20 minute
>averages on the 48 and 576 day average. Is my calculation wrong? I used
>288X24X12 to come up with the 82944. My assumption is that I need that
>value for all 4 positions.

This sounds strange, because RRDtool claims that it will use the 
highest-resolution RRA that has the requested data when generating
a graph. So it *should* pick up the data from the 5-minute RRA.
However, your graphs have the same number of pixels - that might
change how they are displayed, I am not sure. You can try
playing a bit with that: If you right-click on the graph image
and select "View image" (at least in Firefox), it will show just the
graph. In the URL for the graph are two parameters: graph_width and
graph_height. You can try playing with these to test different
sizes for the graphs.

If you decide you need to change the size of the graph images, then
there are settings in xymonserver.cfg (hobbitserver.cfg) for this.


Regards,
Henrik