[rrd-users] how to draw correct graph on server rrdfiles when some of them have zero/null values?
jyavenard at gmail.com
Tue Jan 5 10:01:39 CET 2010
2010/1/5 George-lll <liusoaring at gmail.com>:
> but if some rrd files have zero/null value(indicate some servers got no
> traffic at that period), the charts combined curve drop to zero too.
Are they zero or undefined ?
They do not mean the same thing.
The reason you are seeting what you're describing is because
undefined + anything = undefined..
If the traffic was 0, you should have added 0 to the RRD via rrdtool
update ; According to your RRD definition, if you do not feed any data
for 2 hours, then entry will be undefined for that period.
> wondering there is a data validation before rrdtool starting up, so someone
> let me know hwo to avoid?
What you could do in your CDEF is something like this:
This will replace all unknown values with 0.
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