[rrd-users] Debugging graph smoothing or bad data samples? interpolation bug?

[Marc MERLIN]

http://gargamel.merlins.org/cacti/graph.php?action=properties&local_graph_id=39&rra_id=0&view_type=tree&graph_start=1258302354&graph_end=1258315217

and just in case my data samples were somehow bad (and I checked the source,
they're not), the same thing happened at the same time on another data
source at the same exact times:

http://gargamel.merlins.org/cacti/graph.php?action=properties&local_graph_id=40&rra_id=0&view_type=tree&graph_start=1258302354&graph_end=1258315217

There is just no way it's a concidence.
Also I noticed that what shows up is a data sample with twice the value it
should have and then the next sample is pretty much 0.

The graph definitions are in the links and the rrd was created like so:
/usr/bin/rrdtool create /var/lib/cacti/rra/housepower_21.rrd --step 120  \
DS:HouseNoAC:DERIVE:600:-1000000000:1000000000 DS:House:DERIVE:600:-1000000000:1000000000 \
DS:PGE:DERIVE:600:-1000000000:1000000000 DS:AC:DERIVE:600:-1000000000:1000000000 \
DS:PV:DERIVE:600:-1000000000:1000000000 \
RRA:AVERAGE:0.5:1:2628000 RRA:AVERAGE:0.5:1440:10950  RRA:AVERAGE:0.5:5:3153600 \
RRA:AVERAGE:0.5:30:525600 RRA:AVERAGE:0.5:120:131400 \
RRA:MAX:0.5:1440:10950 RRA:MAX:0.5:30:525600 RRA:MAX:0.5:120:131400 \

I'm just trying to understand what could make these data problems possible.
My original data on disk (before it was fed to the rrd) is correct.
Even if there was a time delay in when the data was given, rrdtool knows how to interpolate
data to make things right, so I don't get it.

Any ideas?

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/