RRDtool graph: empty graph

And all I get with the below call of rrdtool is an empty graph, but why?开发者_开发技巧 No data in database?

rrdtool create connecteclients.rrd --step 300

DS:ConnectedClients:GAUGE:600:0:U
RRA:AVERAGE:0.5:1:432
RRA:AVERAGE:0.5:1:2016
RRA:AVERAGE:0.5:3:2880
RRA:AVERAGE:0.5:12:8640

rrdtool update connectedclients.rrd N:39
-- .. After 5 min again and again.. --

rrdtool graph picture.png \
--imgformat=PNG \
--start=-86400 \
--end=now \
--title="Clients" \
--rigid \
--base=1000 \
--height=96 \
--width=400 \
--upper-limit=2000000 \
--lower-limit=0 \
--slope-mode \
--color "BACK#4095FF" \
DEF:a=connectedclients.rrd:ConnectedClients:AVERAGE \
AREA:a#00CF00:"Clients" \

I notice as well that you setup two RRA files for a one step interval, this should not be a problem, but it is a waste of space and a source of confusion at best.

By setting the upper limit to 2 million and specifying --rigid, your data will be hugging the 0 line so tightly that you might not see it.

Try some examples from the tutorial RRDtutorial to see RRDtool at work.