[rrd-users] data resampling Q

Scott Walters scott at PacketPushers.com
Wed Oct 13 22:33:39 MEST 1999

Hello All,

	I've noticed some unanticipated behavior in the way rrdtool does
data resampling and wanted to make sure it is working as designed.

	I am collecting 5 minute Load Average samples every five minutes.

this is the command i used to create the rrd:

rrdtool create load.rrd DS:la:GAUGE:600:0:U RRA:AVERAGE:0.5:1:384
RRA:AVERAGE:0.5:6:384 RRA:MAX:0.5:6:384 RRA:AVERAGE:0.5:24:384 RRA:MAX:0.5:24:384
RRA:AVERAGE:0.5:288:384 RRA:MAX:0.5:288:384

So I want to average the averages but always keep the MAX.  Now I have
noticed that the true value for the 5 min Load Average is *not* being
recorded in the RRA:AVERAGE:0.5:1:384.  

e.g. i put a load average of 111 (it's really LAx100) into the rrd, but it
never got recorded:

 939831900:     12.00
 939832200:     41.70
# rrtdtool update load.rrd N:111
 939832500:     81.60
 939832800:     12.41

now, if i think to myself the area of the plot 12,41,81,12 vs 12,111,12,12
i think they are probably the same.  so it seems the single sample is
being *averaged* into the RRA somehow, although I just want the 'real'
value of the Load average. 

I've even tried RRA:LAST:0.5:1:384. but that seemed to exhibit the same

I understaned the value of the behavior in certain situations, but i would
really just like the data in RRA:AVERAGE:0.5:1:384 to be raw data as
inputed by 'rrdtool update' without any averaging occuring.


Scott Walters 

"The world speaks IP"

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