On Wed, 13 Aug 2014 10:44:30 -0300 Bruno Galindro da Costa <bruno.galindro@infracerta.com.br> wrote:

> 2014-08-12 11:03 GMT-03:00 Morten Brekkevold <morten.brekkevold@uninett.no>:

>> For port counters, the update frequency is every 5 minutes.

> Is it possible to change it?

Yes, but it will take some dedication.

The collection interval can be easily changed in `ipdevpoll.conf`. The
5minstats job includes the single plugin `statports` every 5 minutes.
Although the job name includes a reference to the 5 minutes, you can
easily change the interval (and the job name, for that matter).

Then there's the problem of the underlying Whisper [1] files. The
Whisper files that Graphite uses to store the port statistics are
created with a storage schema that expects data points every 5 minutes
in the highest precision archive. This is important, see the third
paragraph in the "Differences between Whisper and RRD" section [2].

If you change the the interval away from 5 mintues, you will need to use
the `whisper-resize` command to change the storage schema of all the
port-related Whisper files so the highest precision archive's interval
matches your new interval. If you don't do this, your traffic data and
graphs may become screwed up. If you decrese the interval to, say, 2
minutes, you will not notice any problems, but your data is still stored
at only a 5 minute resolution, and you may have increased the load on
your server and your switches needlessly. If you increase the interval
to, say, 10 minutes, your data will become full of holes as only every
other data slot is filled with data.

You will, of course, also need to change the configured storage schema
for port-related Whisper files in Carbon's `storage-schemas.conf` [3],
to ensure all new port-related Whisper files are created with the
correct schema too.


[1] http://graphite.readthedocs.org/en/latest/whisper.html
[2] http://graphite.readthedocs.org/en/latest/whisper.html?#differences-between-whisper-and-rrd
[3] http://graphite.readthedocs.org/en/latest/config-carbon.html#storage-schemas-conf

--
Morten Brekkevold
UNINETT