On 4/5/11 12:01 PM, "Tobias Oetiker" <t...@oetiker.ch> wrote:
>Hi Jared, > >Today Jared Watkins wrote: > >> I'm working on my first custom rrd project and I'm having an issue with >> things not adding up correctly in a stacked graph. >> >> http://farm6.static.flickr.com/5105/5592424900_9a13016d57_b.jpg >> >> I'm most interested in the max values for this data and if you add up >>all >> the individual max values you get a value that's 120.15 greater than the >> total printed on the graph both visually and in the gprints. Here is >> another example using only 2 samples: >> >> http://farm6.static.flickr.com/5095/5591833819_9a5942d74a_b.jpg >> >> And the relevant code? >> >> RRDs::graph "$img/combined-$interval->{label}.png", >> "$interval->{period}", "$interval->{end}", >> "-t DSL Aggerate - $interval->{label}", >> "-h", "$interval->{rezH}", "-w", "$interval->{rezW}", >> "-l 0", >> "-a", "PNG", >> "-v bits/sec", >> "-b", "1000", >> "DEF:er01agas1in=$rrd_dir/er01.yul01.30004.rrd:in:MAX", >> "DEF:er01agas1out=$rrd_dir/er01.yul01.30004.rrd:out:MAX", >> "DEF:er01agas2in=$rrd_dir/er01.yul01.1418299.rrd:in:MAX", >> "DEF:er01agas2out=$rrd_dir/er01.yul01.1418299.rrd:out:MAX", >> "DEF:er01agas3in=$rrd_dir/er01.yul01.1385232.rrd:in:MAX", >> "DEF:er01agas3out=$rrd_dir/er01.yul01.1385232.rrd:out:MAX", >> "DEF:er01agas4in=$rrd_dir/er01.yul01.1819030.rrd:in:MAX", >> "DEF:er01agas4out=$rrd_dir/er01.yul01.1819030.rrd:out:MAX", >> "DEF:er02agas1in=$rrd_dir/er02.yul01.6.rrd:in:MAX", >> "DEF:er02agas1out=$rrd_dir/er02.yul01.6.rrd:out:MAX", >> >> >> >>"CDEF:totalin=er01agas1in,er01agas2in,er01agas3in,er01agas4in,er02agas1in >>,+, >> +,+,+", >> >> >> >>"CDEF:totalout=er01agas1out,er01agas2out,er01agas3out,er01agas4out,er02ag >>as1 >> out,+,+,+,+", >> >> "LINE1:totalout#000000:Total Out ", >> "GPRINT:totalout:MAX: Max\\: %5.2lf %S", >> "GPRINT:totalout:AVERAGE: Avg\\: %5.2lf %S", >> "GPRINT:totalout:LAST: Current\\: %5.2lf %Sbits/sec\\n", >> >> The data is being collected every 60 seconds and the rras are setup to >>keep >> 7 days worth of 1 minute samples and 3 years worth of daily max values >>for >> long term peak trending. I can't find any reason these shouldn't be >>adding >> up.. and I'm at a loss as to how to fix it. > >within the chart, the data gets pre-consolidated to the pixel >resolution of the graph, so if one pixel is 2 minutes wide, the >incoming max values will be consolidated into one slot using the >same consolidation function used on the original data ... > >when you then add these pre consolidated max values the result will >be larger the total ... >How does that explain the second example with only two samples? If you >add the max values up manually you get a value that is 21.9 higher than >the total showing on the graph. I considered this and played with >different graph resolutions and time periods (getting it to one pixel per >sample) but that didn't correct it. If I do a graph with only one sample >the total comes out correct.. but any more than that and it's off by an >increasing amount that I can't pin down. Thanks, J _______________________________________________ rrd-users mailing list rrd-users@lists.oetiker.ch https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users