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I have written my first Munin plugin to monitor my WAN traffic at home. The chart includes the actual traffic (as DERIVE) and the maximum possible speed (as GAUGE) for my Internet connection.

I want to exclude the maximum speed in the monthly and yearly chart as it scales the chart to a point where there is no information gain anymore.

enter image description here

Using LINE0 would remove the actual charting of the values but still keep the scaling. Is there a way to have the MAX field only displayed for the "by day" and "by week" chart?

Christian Stade-Schuldt
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1 Answers1

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yes it is possible. on 'config' phase you should print to stdout:

graph_args --upper-limit 100 --lower-limit -20 --rigid

in this example draw is upscalling max to 100, and downscalling max to -20. you can change this. special option -rigid cause, out of scale values doesn't change rescalling. Note, scalling is applicable for all draws. time period doesn't matter. It isn't possible apply any limitations to one time period, and remove them from another time period.

optionally you can use bps.cdef configuration item and write equation that limit maximum value. but it is a bit complicated. see the page http://www.caida.org/tools/utilities/rrdtool/manual/rrdgraph.html for details, and how CDEF is working. Note, expression should be written as reverse polish notation. for example if you want limit upper value (independed on time), you can write:

bps.cdef 20,bps,20,bps,LT,IF

it means: IF 20 < bps THEN 20 ELSE bps
a bit crazy. isn't it?

you can extend this equation by adding dependency on time. but do you really want this?

Znik
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