Cacti showing inaccurate values

[General_Dark]

Hello.
The company I'm currently working on is at this moment using PRTG to monitor the network with graphs.
However, after setting up Cacti we noticed that PRTG and Cacti is showing different values from the same devices.
I've tried to zoom in to the cactigraph to make it compareable to the one from PRTG.
(If you can explain the graphgaps, that would be awesome too;).)
Any idea how this can be so different?
It has to be said that the cactibox is running cactiez 0.4 on a desktop pc and prtg on a w2k3 server.
Hoping for replies
//GD

[gandalf]

I don't know what's underneath the PRTG.
Does this occur even on graphs showing data of last day?
Reinhard

[General_Dark]

Yes it does, but I noticed something new:

The problem accure only on high bandwidth use, like over 400Mbit/s.
This night we had a peak (used SNMP v2 instead of v1) and after the peak there was a fall down to alot lower values, please see the new attached picture.
Even tho the useage of the link was above 800Mbit/s for hours it doesnt show on the graphs.
We measured the local interface on the server and it is compareable to the PRTG version, not cacti.

[gandalf]

Please find the MAX setting of the rrd file's data source. If it's too low, it may clip off data
Reinhard

[General_Dark]

Its already at 1000 000 000, should be enough for gigabit interface, right?
1000000000 bit = 953.674316406 megabit
According to http://www.translatorscafe.com/cafe/uni ... o-megabit/.
However I increased it to 100 000 000 000 (hundred billions) to see if theres a change.

[General_Dark]

I did adjust the max value, but there's still no change.
Any ideas?

[General_Dark]

Shameless bumping in hope for an update?

[punctt]

check this out

http://forums.cacti.net/viewtopic.php?t=24526