[rrd-users] Question about time stamp, etc with GAUGE DST

Steve Shipway s.shipway at auckland.ac.nz
Fri Nov 9 04:48:35 CET 2012

RRDTool Data Normalisation.  RRDTool interpolates the data to fit into the predefined time ‘buckets’.  You cannot store the data with the exact time you enter them (well, unless you do some very weird things using a 1second step and large heartbeat but that causes other problems) unless you ensure each data point is logged exactly on a time window boundary.


See Alex’s excellent tutorial:  http://www.vandenbogaerdt.nl/rrdtool/process.php





Steve Shipway

ITS Unix Services Design Lead

University of Auckland, New Zealand

Floor 1, 58 Symonds Street, Auckland

Phone: +64 (0)9 3737599 ext 86487

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Email:  <mailto:s.shipway at auckland.ac.nz> s.shipway at auckland.ac.nz

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From: rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch [mailto:rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch] On Behalf Of Chris Nighswonger
Sent: Friday, 9 November 2012 3:26 p.m.
To: rrd-users at lists.oetiker.ch
Subject: [rrd-users] Question about time stamp, etc with GAUGE DST


What is it that I do not understand about the timestamps in the following RRD?  Just below it is the actual data as inserted into the RRD via RRDs::update. Below that is the fetch of what the same data looks like in the RRD.

My question is why is the data from time 1352425184 split across two steps? I'm guessing it has to do with the difference between the --start value and when the logging daemon is started. What I am trying to achieve is the data point recorded in a single step. Is this possible?

Kind Regards,


rrdtool create sperrors.rrd --start now --step 60 \
DS:align-err:GAUGE:120:0:100000 \
RRA:AVERAGE:0.5:1:10080 \
RRA:MAX:0.5:1:10080 \
RRA:LAST:0.5:1:1 \
RRA:AVERAGE:0.5:60:1440 \
RRA:MAX:0.5:60:1440 \
RRA:AVERAGE:0.5:720:732 \

Data being inserted into RRD:


Output of "$rrdtool fetch sperrors.rrd AVERAGE --start 1352424941"


1352424960: 0.0000000000e+00
1352425020: 0.0000000000e+00
1352425080: 0.0000000000e+00
1352425140: 6.3333333333e-01
1352425200: 1.4666666667e+00
1352425260: 0.0000000000e+00
1352425320: 0.0000000000e+00
1352425380: 0.0000000000e+00
1352425440: 0.0000000000e+00
1352425500: 0.0000000000e+00
1352425560: 0.0000000000e+00

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