[rrd-users] Average/Min/Max

[Nunners]

Has anyone been able to make comment on this?  I'm guessing I need to use a
CDEF, but can't work ot exactly whatto define when using them...

THanks
Nunners



Nunners wrote:
> 
> I’ve recently changed from using mrtg to using rrdtool, and am having
> problems with the averages, min and max.
> 
> The example I’ll use relates to me graphing the outside temperature, I
> have an xml feed from my little weather station, which produces the
> temperature and dew point therefore there are two readings to be stored
> and then graphed etc…
> 
> rrdtool create weather_temp.rrd --start 1162636707
> DS:temp:GAUGE:600:-100:100 RRA:AVERAGE:0.5:1:24 RRA:AVERAGE:0.5:1:600
> RRA:AVERAGE:0.5:6:700 RRA:AVERAGE:0.5:24:775 RRA:AVERAGE:0.5:288:797
> RRA:MAX:0.5:1:600 RRA:MAX:0.5:6:700 RRA:MAX:0.5:24:775 RRA:MAX:0.5:288:797 
> RRA:MIN:0.5:1:600 RRA:MIN:0.5:6:700 RRA:MIN:0.5:24:775 RRA:MIN:0.5:288:797
> rrdtool create weather_dewpoint.rrd --start 1162636707
> DS:temp:GAUGE:600:-100:100 RRA:AVERAGE:0.5:1:24 RRA:AVERAGE:0.5:1:600
> RRA:AVERAGE:0.5:6:700 RRA:AVERAGE:0.5:24:775 RRA:AVERAGE:0.5:288:797
> RRA:MAX:0.5:1:600 RRA:MAX:0.5:6:700 RRA:MAX:0.5:24:775 RRA:MAX:0.5:288:797 
> RRA:MIN:0.5:1:600 RRA:MIN:0.5:6:700 RRA:MIN:0.5:24:775 RRA:MIN:0.5:288:797
> 
> A cron updates them appropriately every 5 mins.
> 
> I’ve then got a graph which adds both value on, really nicely:
> /usr/bin/rrdtool graph /var/www/mrtg/weather_temp-day.png --start -86400
> --vertical-label oC
> DEF:temperature_area=/etc/mrtg/weather_temp.rrd:temp:AVERAGE
> DEF:temperature=/etc/mrtg/weather_temp.rrd:temp:AVERAGE
> DEF:dewpoint=/etc/mrtg/weather_windchill.rrd:temp:AVERAGE
> AREA:temperature_area#00FF00 LINE1:temperature#0000FF:"Temperature"
> LINE2:dewpoint#FF0000:"Dew Point"
> 
> The problem I’m having is on the page I display the graph, I also want the
> max min and average temperatures for the graph being displayed (I have
> day, week, month, year and “historical” – using the complete set of data
> available)… I am therefore trying to call:
> MAX: /usr/bin/rrdtool fetch /etc/mrtg/weather_temp.rrd MAX --start -86400
> AVERAGE: /usr/bin/rrdtool fetch /etc/mrtg/weather_temp.rrd AVERAGE --start
> -86400
> MIN: /usr/bin/rrdtool fetch /etc/mrtg/weather_temp.rrd MIN --start -86400
> 
> All I get back is the following:
> 1262680200: nan
> 1262680200: nan
> 1262680200: nan
> 
> I haven't included the html/php stuff, as obviously it's irrelevant to the
> direct problem but I know that all works!  I’m guessing it’s something to
> do with when the data started and it not recognising the null values –
> therefore what’s the easiest way to get it to ignore the null values?
> 
> Thanks
> James
> 
> 
> 
> 

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