[rrd-users] Fwd: Duplicate values along the Y-axis of a graph

[Alex van den Bogaerdt]

On Wed, May 02, 2007 at 12:52:07PM -0600, David Ball wrote:
>    Resending this message without the image attachment, as it wasn't
> making it past the moderator (or at least, he/she/they haven't
> permitted it yet, as far as I know).

At least one of the moderators has been, is, and will be quite busy.
Sorry for that. Apparently the other moderators were also unavailable.
FWIW, I would have rejected your post anyway. Too big is too big. Please
use a link to some website next time. If you don't have a public website,
use one of the free photo-sharing sites.

> ---------- Forwarded message ----------
> From: David Ball <davidtball at gmail.com>
> Date: Wed, 2 May 2007 09:00:59 -0600
> Subject: Duplicate values along the Y-axis of a graph
> To: rrd-users at lists.oetiker.ch
> 
>   I'm generating graphs (successfully) for over 160 interfaces, and
> ONE of them (that I've discovered so far) has this strange tendency to
> show duplicate values down the Y-axis.  Can anyone provide a hint as
> to why they think this may be occurring?  I'm not even sure where I
> should start looking.  See attached .png for an example.  I'm not
> specifying any -y, -Y, --units-exponent, etc. which might alter the Y
> axis values.  They're being determined automagically by RRDTool.
>   Thanks in advance for any light that might be shed.

I've seen this myself.  It happens when all rates are close together
and high.  Example: all rates are between 1,100,100 and 1,100,400.
RRDtool may be displaying 1.1M a couple of times. (I don't know if
the example is actually working as I just told; it is just for the
discussion). The grid lines are placed at 1,100,000 (1.1M rounded),
1,100,100 (also 1.1M rounded), 1,100,200 and so on.

One of the options will make RRDtool behave better in this case.
I think it is --alt-y-grid.

HTH
-- 
Alex van den Bogaerdt
http://www.vandenbogaerdt.nl/rrdtool/