[rrd-users] clarification of graph resolution

Spencer Anderson spanders at awebduck.com
Tue May 8 18:23:53 CEST 2007

I am trying to pick the best graph size for the data I'm trying to present.
I collect data every minute and would like to show 24 hours of data on one
graph.  Am I correct in assuming that at the default resolution, 1 data
point = 1 pixel, I would need a graph 1440 (24 hours * 60 minutes) pixels
wide to hold all the data points?

Also, if I leave the default resolution, and create a "last 24 hours" graph
that is 600 pixels wide, the data still looks like it is my one minute data
points, even thought there is no way they could all fit in a 600 pixel
graph.  Is RRD averaging the data points so they fit, or just skipping some
so they fit?

Here is the command I used to create my RRD.  Basically, I keep 16 days of 1
minute data, 90 days of 1 hour averages, and approx 3 years of daily

rrdtool create Router01 --step 60 \
    DS:data:GUAGE:115:0:U \
    RRA:AVERAGE:0.5:1:23040 \
    RRA:AVERAGE:0.5:60:2160 \
    RRA:AVERAGE:0.5:1440:1100 \
    RRA:MAX:0.5:60:2160 \
    RRA:MIN:0.5:60:2160 \
    RRA:MAX:0.5:1440:1100 \
    RRA:MIN:0.5:1440:1100 \
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