Tuesday, 14 January 2020

Visualising data from iperf with rrd

The purpose of this test was to test the availability of bandwidth on a leased line while ensuring that the test itself didn't saturate the line.

We'll firstly run our iperf server in daemon mode:

iperf3 --server --daemon --logfile iperf_stdout.txt --pidfile iperf3.pid

Since this will be a long term test we'll ensure that there is no timeout on the test and that intervals of 1 second are reported (since we'll be using this for rrd input):

iperf3 -b 20M -c hlxscript01.hlx.int -i 1 -t 0 -V --logfile log.txt &

In the above example I'm sending a stream traffic equalling 20Mbits. If you wish to saturate the line you will need to remove this and also likely tweak with threads and the TCP window size in order to get optimum results.

Now in order to use our client log (log.txt) for use with rrd we'll need to extract the timestamp along with the recorded speed, feed it into the rrd file and finally generate the graph. I've created a simple shell script to do just that:

#!/bin/bash

epoc=$(date "+%s")

IFS=$'\n'
iperf_results=( $(cat log.txt | grep -o '[0-9]\+\.[0-9]\+ Mbits\/sec' | cut -d " " -f 1) )
results_count="${#iperf_results[@]}"

rrdtool create iperf.rrd --step=1 --start=$epoc-$results_count DS:ds1:GAUGE:1:U:U RRA:AVERAGE:0.5:1:$results_count

START=$(expr $epoc - $results_count)
COUNT=$results_count
for (( i = 0; i < ${COUNT}; i++ )); do
VALUE=${iperf_results[i]}
rrdtool update iperf.rrd ${START}:${VALUE}
START=$(expr ${START} + 1)
done

rrdtool graph iperf.png --start $epoc-$results_counts --end now DEF:ds1a=iperf.rrd:ds1:AVERAGE LINE1:ds1a#FF0000:"Sinus line"

Sources

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