[rrd-users] trying to understand the relationship between source data, what's in rrd and what gets plotted

Mark Seger Mark.Seger at hp.com
Fri Jul 20 15:59:26 CEST 2007

I'm sure it's me and not rrdtool, but I can't figure out what's 
happening!  Here's what did:
- I have a data that has been generated at 1 second intervals
- generated a plot with gnuplot as a known quantity
- loaded the same data into rrdtool as absolute values and also with an 
interval of 1 sec
- did a fetch of all the data
- converted it to something I could load into excel and compare with the 
original values to make sure correct.  they do NOT agree but are close.  
perhaps I a still to new to rrdtool to appreciate how my data can get 
adjusted, but I also would have thought using absolute and 1 second 
samples there wouldn't be anything to adjust.  that's question 1.  is 
there a way to make it not do that?  I want to plot the values I've 
recorded and not some manipulated value.  that's question 2.
- then I plotted the data and while the plots have the same 'pattern' 
they do not agree with the data.  in other words, the values stored in 
rrd have several valued over 40K but when I look at the plot, I don't 
see any values above 28K.  is rrd playing with the values stored in its 
data base or am I using the plotting tool incorrectly?  that's question 3.


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