[rrd-users] weird behaviour of rrd graph

[devzero at web.de]

Hello, 

i`m seeking for an explanation of the following problem, but i don`t have a clue what`s happening here.

I`m using RRDtool 1.2.23 on an embedded mips32 platform and it`s working considerably well.

every night the yearly graph is generated and looks ok:
http://umweltsuen.de/tmp/power-1y-ok.png

there is only one exception:
from time to time, the resolution of the graph changes, and it looks like this:
http://umweltsuen.de/tmp/power-1y-wrong.png
(this happened twice now, after more than 1 1/2 months without problems)

maybe someone has an explanation, what`s causing this effect and how to avoid it ?
it does not happen with the other graphs (monthly, weekly, daily, hourly....), only
the yearly graph is affected. 

this is the create command:
rrdtool create test.rrd --step 5 \
DS:Power1:GAUGE:180:0:10000 \
DS:Power2:GAUGE:180:0:10000 \
DS:Power3:GAUGE:180:0:10000 \
RRA:AVERAGE:0.5:1:3200 \
RRA:AVERAGE:0.5:6:3200 \
RRA:AVERAGE:0.5:36:3200 \
RRA:AVERAGE:0.5:144:3200 \
RRA:AVERAGE:0.5:1008:3200 \
RRA:AVERAGE:0.5:4320:3200 \
RRA:AVERAGE:0.5:52560:3200 \
RRA:AVERAGE:0.5:525600:3200 \

this command creates the graph:
rrdtool graph power-1y.png  --title "Energieverbrauch 
letztes Jahr" --start end-1y  --end now --width 880 --height 300 --slope-mode 
--vertical-label VoltAmpere --lower-limit 0 --alt-autoscale-max  'DEF:Power1=test.rrd:Power1:AVERAGE 
DEF:Power2=test.rrd:Power2:AVERAGE DEF:Power3=test.rrd:Power3:AVERAGE 
CDEF:Ln1=Power1,Power1,UNKN,IF CDEF:Ln2=Power1,Power1,Power2,+,UNKN,IF 
CDEF:Ln3=Power3,Power1,Power2,Power3,+,+,UNKN,IF AREA:Power1#A0A0FF:Phase1 
AREA:Power2#A0FFA0:Phase2:STACK AREA:Power3#FFA0A0:Phase3\j:STACK 
LINE1:Ln3#AA0000 LINE1:Ln2#00AA00 LINE1:Ln1#0000AA'


thanks for help!
regards
roland
___________________________________________________________
WEB.DE DSL SOMMER-SPECIAL: Surf & Phone Flat 16.000 für 
nur 19,99 €/mtl.!* http://produkte.web.de/go/DSL_Doppel_Flatrate/2