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

[Steve Shipway]

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

 

  _____  

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

DDI: +64 (0)9 924 6487

Mobile: +64 (0)21 753 189

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

P Please consider the environment before printing this e-mail 

 

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,
Chris


RRD:

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 \
RRA:MAX:0.5:720:732


Data being inserted into RRD:

1352424941:0
1352425001:0
1352425061:0
1352425121:0
1352425184:2
1352425244:0
1352425304:0
1352425364:0


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


                      align-err

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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