[rrd-users] Why do I see NaN values?

[Leon Stringer]

Hi,

I've created an RRD database to store a value (server clock offset in
ms). I've created a cron job to add the value every 6 hours. As far
as I can tell the job is running correctly and getting a valid value.
However, when I run rrd fetch I get a lot of NaN values (between a
quarter and a third of values) so the generated graphs have gaps too.

I created the file with:

  rrdtool create file.rrd -s 21600 DS:offset:GAUGE:21600:U:U
      RRA:MAX:0:1:360
      
I add the data with:

  rrdtool update file.rrd N:<val>	(E.g. 1.903, -0.424, etc.)

And I query data with:

  rrdtool fetch -s -1week file.rrd MAX

Can anyone tell me why I see NaN values instead of the values I
(think!) am putting in?

Thanks in advance,

Leon...

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