On 2014-07-04 09:03, Cardinal-Richards, Emma wrote:
On 25 Jun 2014, at 20:35, Adam Armstrong adama@memetic.org wrote:
On 2014-06-24 05:25, Cardinal-Richards, Emma wrote: Hi, On (seemingly all) our device port pages I get different values in the legends on the page of graphs vs their respective hover over pop-up graphs? In theory I thought they're showing the same timeframe/data?
RRD gonna do what RRD gonna do!
RRD generates the legend based on the data it has decided to use for the
graph. This depends on the time period and the resolution of the data. None of our code is involved in any of this.
Note that without a screenshot, no one knows what you're talking about,
and even fewer people are going to try to guess.
adam.
I know you were anxiously awaiting this....
I've attached a screenshot as an example, the popup graph is of the 3rd graph along. The numerical values differ, this seems to be the same on the majority of graphs not just 'traffic', and not for all values (some match).
This is because RRD is choosing a different resolution of data for the two graphs. It doesn't need all of the data in the higher resolution dataset for the smaller graph, so it uses the more aggregated data.
The average number stays the same because the number of bits moved is the same in each resolution. The "max" (and "min", if it was visible on that graph) also stays the same, because min/max has a more restricted dataset with fewer resolutions for rrdtool to choose from.
This is an annoying, but well known, attribute of rrdtool.
Also. Do not ever use rrdtool's 95th %ile calculations for anything important. Never. Ever.
adam.