[collectd] huge values with tail plugin

[Florian Forster]

Hi,

On Mon, Mar 01, 2010 at 05:30:20PM +0100, Manuel CISSE wrote:
> […] from time to time I have huge values (last was 229.1M for "Local
> delivered") in the RRD database.
> 
> Does anybody what could be causing this behaviour?

this is most likely caused by a "counter reset", i.e. the counter is
reset to zero and collectd thinks an overflow occurred.

This problem can be solved in one of two ways:

1) Set a maximum value for the RRD file. You can use "rrdtool tune" to
   do this, see the rrdtune(1) manual page. Values larger than this
   maximum value will be discarded by RRDtool.

2) Use the (kind of) new "derive" data type instead and set its
   minimum [sic] value to zero. Because DERIVE doesn't handle overflows,
   it will consider the reset to be a (huge) negative value and due to
   the minimum value the data point will be discarded as invalid.

Regards,
—octo
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
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