[rrd-users] RRD files not correctly storing the values added using rrdtool update

A Darren Dunham ddunham at taos.com
Thu Sep 3 21:19:24 CEST 2009

On Thu, Sep 03, 2009 at 05:33:50PM +0200, Traiano Welcome wrote:
> Hi List
> I'm seeing what appears to be my rrd files not storing the values I 
> added using "rrdtool update", i.e I update the rrd file with one set of 
> values (network traffic_in and traffic_out counter values) and rrdtool 
> fetch shows completely different values for the corresponding 
> time-slots. This causes me to wonder if my rrd update options or rrd 
> file structure is wrong. Process illustrated below:

A COUNTER will use the difference between successive updates and the
times of the updates to calculate a rate.  It won't store the raw data
you enter.

> DS:traffic_in:COUNTER:600:0:1.8446744074e+17 \
> DS:traffic_out:COUNTER:600:0:1.8446744074e+17 \

> Values are polled using snmpget and updated every 5 minutes (from cron) 
> using this rrdupdate command, for example:
> ---
> rrdtool update vlan_interface_traffic.rrd 1251991500:146522079:2005725
> ---

Withouth showing an adjacent update, we can't tell what would be

> Correspondingly, the graphs show  traffic several orders of magnitude 
> lower than it should.

You're seeing the differences, not the raw numbers.  


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