[rrd-users] Any tips for optimising file size of trends ?

Mr Robert Conway rjconway at bigpond.com
Fri May 15 01:10:47 CEST 2009

I had been wondering if there is any way or options in reducing the file size of the generated trends.  As I now use a date slider and allow the user to interact with the trend, file size (transfer speed) plays a big part in the user experience.  The creation of the file via the cgi file on the server is really fast, less than 1 second.  I understand the acutal height/width play a significant role however did not know if there are any more optimal formats or switches that can be used to minimise the file size of the generated trend.

This is a code snippet from my cgi file:
rrdtool graph /var/www/aqua.png --start $STIME --end $ETIME \
--upper-limit $HIGHSCALE --lower-limit $LOWSCALE --slope-mode --units-length 2 \
--interlaced \
--rigid \
--width $WIDTH --height $HEIGHT \
--vertical-label "pH\n" \
--color CANVAS#000000 \
--title "Aquarium pH" \
DEF:phv=/var/www/rrd/aqua_ph.rrd:P1:AVERAGE  LINE1:phv#0000FF:"Ph=" \
VDEF:phlast=phv,LAST GPRINT:phlast:"%3.2lf%S" \
VDEF:phavg=phv,AVERAGE GPRINT:phavg:"avg=%3.2lf%spH      " \
--watermark "Aquarium PH Graph">/dev/null


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