[rrd-users] Update not working

Simon Hobson linux at thehobsons.co.uk
Wed Apr 13 22:54:11 CEST 2011

ArtOfLosing wrote:

>Ik know everybody has problems with updates not working, but i have been
>buzy a few days and i can't get it to work. I have created te following a
>RRDtool database:
>rrdtool create /root/mde.rrd --step 300 \
>DS:kwh1:COUNTER:300:U:U \
>RRA:LAST:0:1:2016 \
>RRA:LAST:0:3:2921 \
>RRA:LAST:0:12:8765 \
>With this database i want to add a value every 5 minutes (300 seconds).
>I have a cronjob which runs every 5 minutes. It adds a value with the
>folling command:
>rrdtool update /root/mde.rrd N:20
>But if i use RRDtool fetch i only get NaN. So... what am i doing wrong?

Probably you need to change your heartbeat value. You currently have 
this set to 300, so if two updates are more than 300 seconds apart 
then the data becomes unknown - from the previous update to the 
current one. Given the slight variation in run times, many of your 
updates will be more than the heartbeat apart and so you'll have many 
gaps in the data.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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