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Tom Smykowski
Asked: 2010-11-29 07:47:07 +0800 CST

How to populate RRD database with CPU and MEM usage data?

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I have a Lighttpd server (on Centos) and would like to display 4 graphs: lighttpd traffic, lighttpd requests per second, CPU usage and MEM usage. I've set place for rrd database for lighttpd config like this:

rrdtool.binary = "/usr/bin/rrdtool"
rrdtool.db-name = "/var/www/lighttpd.rrd"

And put into my WWW cgi-bin sh file that gets data from lighttpd RRD file and creates graphs of traffic and requests per second like this:

#!/bin/sh

RRDTOOL=/usr/bin/rrdtool
OUTDIR=//var/www/graphs
INFILE=/var/www/lighttpd.rrd
OUTPRE=lighttpd-traffic
WIDTH=400
HEIGHT=100

DISP="-v bytes --title TrafficWebserver \
        DEF:binraw=$INFILE:InOctets:AVERAGE \
        DEF:binmaxraw=$INFILE:InOctets:MAX \
        DEF:binminraw=$INFILE:InOctets:MIN \
        DEF:bout=$INFILE:OutOctets:AVERAGE \
        DEF:boutmax=$INFILE:OutOctets:MAX \
        DEF:boutmin=$INFILE:OutOctets:MIN \
        CDEF:bin=binraw,-1,* \
        CDEF:binmax=binmaxraw,-1,* \
        CDEF:binmin=binminraw,-1,* \
        CDEF:binminmax=binmaxraw,binminraw,- \
        CDEF:boutminmax=boutmax,boutmin,- \
        AREA:binmin#ffffff: \
        STACK:binmax#f00000: \
        LINE1:binmin#a0a0a0: \
        LINE1:binmax#a0a0a0: \
        LINE2:bin#efb71d:incoming \
        GPRINT:bin:MIN:%.2lf \
        GPRINT:bin:AVERAGE:%.2lf \
        GPRINT:bin:MAX:%.2lf \
        AREA:boutmin#ffffff: \
        STACK:boutminmax#00f000: \
        LINE1:boutmin#a0a0a0: \
        LINE1:boutmax#a0a0a0: \
        LINE2:bout#a0a735:outgoing \
        GPRINT:bout:MIN:%.2lf \
        GPRINT:bout:AVERAGE:%.2lf \
        GPRINT:bout:MAX:%.2lf \
        " 

$RRDTOOL graph $OUTDIR/$OUTPRE-hour.png -a PNG --start -14400 $DISP -w $WIDTH -h $HEIGHT
$RRDTOOL graph $OUTDIR/$OUTPRE-day.png -a PNG --start -86400 $DISP -w $WIDTH -h $HEIGHT
$RRDTOOL graph $OUTDIR/$OUTPRE-month.png -a PNG --start -2592000 $DISP -w $WIDTH -h $HEIGHT

OUTPRE=lighttpd-requests

DISP="-v req --title RequestsperSecond -u 1 \
        DEF:req=$INFILE:Requests:AVERAGE \
        DEF:reqmax=$INFILE:Requests:MAX \
        DEF:reqmin=$INFILE:Requests:MIN \
        CDEF:reqminmax=reqmax,reqmin,- \
        AREA:reqmin#ffffff: \
        STACK:reqminmax#00f000: \
        LINE1:reqmin#a0a0a0: \
        LINE1:reqmax#a0a0a0: \
        LINE2:req#00a735:requests" 

$RRDTOOL graph $OUTDIR/$OUTPRE-hour.png -a PNG --start -14400 $DISP -w $WIDTH -h $HEIGHT
$RRDTOOL graph $OUTDIR/$OUTPRE-day.png -a PNG --start -86400 $DISP -w $WIDTH -h $HEIGHT
$RRDTOOL graph $OUTDIR/$OUTPRE-month.png -a PNG --start -2592000 $DISP -w $WIDTH -h $HEIGHT

Basically it's not my script, i get it from somewhere from the internet. Now i would like to do the same for CPU usage and MEM usage. I don't like to use any additional packages!

As you can see lighttpd populates lighttpd.rrd file with traffic data and requests per second. Now i would like to the system to populate second rrd file with CPU and MEM usage, so i can add to sh file code to generate graphs for this data.

How can I populate RRD file with CPU and MEM usage data? Please, NO THIRD-PARTY tools !

linux centos rrdtool shell

2 Answers

  1. So, if you want to really control that yourself, you will first need to define your own rrd file for this data, meaning you need to know what you want to store for how long. Then you have to populate this, likely from a script. The data you are looking for is in /proc/meminfo and /proc/loadavg, you have to parse this data and feed it into rrdtool.

    How to define and populate your own rrd file is documented excellently by the rrdtool creators, so I'll just refer you to this documentation.

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  2. Maybe it is worth to take a look how collectd (a small C daemon collecting statistics to rrd files) does it:

    http://git.verplant.org/?p=collectd.git;a=blob;f=src/cpu.c;h=12071a2ca8bae25cf86f25782a682ad1bf898846;hb=HEAD#l363

    Here you can find how it reads /proc/stat and parses its content then you can easily write a bash script.

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