Interesting point...  I don't like recompiling, so I'll wait until I
upgrade and play with this "feature"...

Thanks!

Gary


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Graeme Fowler
Sent: Monday, March 02, 2009 3:47 PM
To: [email protected]
Subject: Re: [Ntop] rrd graphs misleading (stacked instead of overlayed)

On Mon, 2009-03-02 at 12:24 -0600, Gary Gatten wrote:
> Some / many graphs (rrd) are misleading as they are "stacked" instead
> of "overlayed"  For example:
<snip>
> Has anyone else noticed this and is there a fix?

I wouldn't say this is a bug (I know you're not!), it's more of a
feature.

Imagine you had 20 different protocol data sets on the same graph (not
inconceivable considering your followup graph has 19!). Imagine that
they generally run within 5-10% of each other in terms of throughput
(ie. roughly 5% each of the total traffic).

You'd be hard pressed to separate them; the dominant line would be the
last defined one (in your case, WinMX would overdraw the others) and the
throughput on the Y axis would not reflect the true, combined
throughput.

In RRDTool terms, using STACK instead of LINE[12] or AREA allows the
full combination of the data to be shown (as long as the dataset
includes all the data, obviously) and means you can see graphically
which of the protocols contributes most at any given time.

In my experience, using STACK alongside an overview graph allows the
same data to be shown at the same scale, with the obvious contributors
standing out. Using LINE[12] or AREA means the dominant colour *or* the
last dataset stand out, which can be confusing for large sets of data
(like yours).

If you're willing to recompile I bet you could find the bit in the
source that does STACK and change it to AREA. Then you'll get some
*really* misleading graphs!

Graeme


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