[rrd-users] Strange issue with large step value

[Alex van den Bogaerdt]

I guess the problem may have to do with the fact that your time stamps are 
not a whole multiple of your step size.

Not as a solution, but as a means to investigate the problem: try to 
populate an RRD with a step size of an hour, and plenty of room in a couple 
of RRAs. See if your data makes it into the database and is as expected.

----- Original Message ----- 
From: "_ JvG _" <jj at knowzone.org>
To: <rrd-users at lists.oetiker.ch>
Sent: Monday, May 04, 2015 4:24 PM
Subject: [rrd-users] Strange issue with large step value


> Hi,
>
> I'm trying to import some old data (collected once every week at 19.00 
> hour
> on Sunday)
>
> This is what I did:
>
> rrdtool create pymeter-weekdata.rrd \
>    --start 1419184800 \
>    --step 604800 \
>    DS:qtotal:COUNTER:907200:0:100000 \
>    RRA:AVERAGE:0.5:1:53
>
> rrdtool update pymeter-weekdata.rrd 1419789600:50628
> rrdtool update pymeter-weekdata.rrd 1420398000:50803
> rrdtool update pymeter-weekdata.rrd 1421002800:50959
> rrdtool update pymeter-weekdata.rrd 1421607600:51120
>
> rrdtool xport  \
>    --start 1419184800 \
>    --end 1425236400 \
>    --step 604800  \
>    DEF:Qtotal=pymeter-weekdata.rrd:qtotal:AVERAGE \
>    CDEF:QTot=Qtotal,604800,*,100,/  \
>    XPORT:QTot:"Usage\n"
>
> and I get this:
>
> <xport>
>  <meta>
>    <start>1419465600</start>
>    <step>604800</step>
>    <end>1419465600</end>
>    <rows>11</rows>
>    <columns>1</columns>
>    <legend>
>      <entry>Usage\n</entry>
>    </legend>
>  </meta>
>  <data>
>    <row><t>1419465600</t><v>NaN</v></row>
>    <row><t>1420070400</t><v>NaN</v></row>
>    <row><t>1420675200</t><v>1.6573076923e+00</v></row>
>    <row><t>1421280000</t><v>1.5829166667e+00</v></row>
>    <row><t>1421884800</t><v>NaN</v></row>
>    <row><t>1422489600</t><v>NaN</v></row>
>    <row><t>1423094400</t><v>NaN</v></row>
>    <row><t>1423699200</t><v>NaN</v></row>
>    <row><t>1424304000</t><v>NaN</v></row>
>    <row><t>1424908800</t><v>NaN</v></row>
>    <row><t>1425513600</t><v>NaN</v></row>
>  </data>
> </xport>
>
> while I would expect these results:
>
> 508.03 - 506.28 = 1,75
> 509.59 - 508.03 = 1.56
> 511.20 - 509.59 = 1.61
>
> What did I do wrong or what do I need to correct to get the expected
> results?
>
> JJ
>
> --
>


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