Forum Discussion
Dec 09, 2008
Will you believe that both answers might be right?
The performance graphs are averages over time and use rrdtool under the seams to build the graphs. From my understanding of rrdtool (and it's predecessor mrtg), it uses a sliding normalization for it's data. The most recent data will have more data points per time period and as the time gets older they prune and average those values out so a constant data size can be maintained. If that is the case, then it might make sense that during the averaging process, the data for a specific timestamp may change as time goes by.
I'll have to verify if this is the case for the performance graphs. I'll let you know what I find.
-Joe