[rrd-users] RRD DS:heartbeat and MRTG

[Chris Josephes]

Yesterday I posted a question to the MRTG list about some .rrd files that
appeared to be updating with unknown values for some reason.  I didn't get
any answers, so I did some more digging.

I re-read some of the MRTG source code and then went over the RRD docs,
and I think I may have found what the problem is.

The targets I was monitoring in question with MRTG was set for an Interval
of 15 minutes.  But when MRTG creates the RRD files, it specifies a
hearbeat of 600 seconds for each data source, and a step interval of 300
seconds.

According to the RRD Create page:

               heartbeat defines the maximum number of seconds
               that may pass between two updates of this data
               source before the value of the data source is
               assumed to be *UNKNOWN*.

So am I correct in assuming that MRTG is not correctly taking the Interval
configuration parameter into account when it creates the RRD files?

If so, would it be better if MRTG created the initial RRD with a step
parameter matching the interval and a heartbeat value for the DS equal to
or greater than the interval (Interval + 300 seconds, perhaps).

--                      _______________
 Chris Josephes      __/ MRNet/Onvoy   \
 chrisj at mr.net    __/   www.onvoy.com  /
\________________/

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