[rrd-users] Dealing with spikes due to reachability

Tobias Oetiker tobi at oetiker.ch
Wed Apr 25 19:02:21 CEST 2007


RRDtool has no idea about devices in any way ... the question is
what your script does when it is not able to acquire the data. What
does it feed to rrdtool ?

rrdtool has several saveguards to deal with such situations

* min/max values for each datasource (rates for counter DS)
* minimal required heart beat to catch long gaps in updating
* after a UNKNOWN value has been logged, the internal counters get
  invalidated, and you need two updates to get a valid counter


Today Chris Griffin wrote:

> Hi Tobi,
>  Thanks much for the reply.  I am gathering the counters via SNMP and
> sticking them in the RRD.  It could certainly be my script is doing
> something strange or the counters on the device are bad.  Here is an
> example:
> 1177477260: 7.8335465325e+06 3.4685346764e+06
> 1177477320: 7.0441856350e+06 4.4907708048e+06
> 1177477380: 5.0908686855e+06 2.6347848034e+06
> 1177477440: nan nan
> 1177477500: nan nan
> 1177477560: nan nan
> 1177477620: nan nan
> 1177477680: 2.8324705690e+08 1.6997104436e+08
> 1177477740: 2.9551147168e+07 1.8751196979e+07

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten
http://it.oetiker.ch tobi at oetiker.ch ++41 62 213 9902

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