[rrd-users] rrdgraph never returns with small step

[Alex van den Bogaerdt]

On Wed, Jun 18, 2008 at 10:10:21PM -0400, Josh Wyatt wrote:

> This works fine... It does make a big file though, about 7.3MB.
> 
> The update is via RRDs:
> $e=RRDs::update('bits.rrd','-t','00:01:02:03:04:05:06:07:08:09:10',"N$total");
> The way $total is built, it includes a preceding ':' so that a typical line looks like this:
> $e=RRDs::update('bits.rrd','-t','00:01:02:03:04:05:06:07:08:09:10',"N:35:11:13:12:12:14:10:10:604:591:11");
> 
> And this updates the RRD every second, in a loop.

Not that I expect this to be related to the problem you report, but I
think you may want to consider using timestamps instead of 'N'. When
updates are a bit delayed (e.g. busy computer) it doesn't really matter
for 5-minute updates (e.g. 0.1 second on 300 seconds is 0.3%) but it
does for 1-second updates (e.g. 0.1 second on 1 second is 10%)


> Now, I try to graph:
> /usr/local/bin/rrdtool graph /home/graphs/all.png  -s -30s -w 200 -h 40 -a PNG
>  -A  \
> DEF:00=/home/graphs/bits.rrd:00:AVERAGE \
> LINE1:00#00cccc  

You don't need "--end" ?

Try to isolate the problem.

This is 30 seconds, on 200 pixels.  That is 6.66666.... pixels per
second.  It shouldn't be a problem, but just to be sure you should
try with something more sane, like -s-30s -w 300.

Try fetching the data (rrdtool fetch -s -30s /home/graphs/bits.rrd AVERAGE).
Does that hang, or not. If it does, the problem is probably somewhere
in the data collection part, else if will probably be in the graph part.

Data:
Try using another disk (no NFS, no data storage card, different filesystem.)
Try building RRDtool with/without mmap.

Graph:
Try switching off the X-axis label. If it then works, try to find
a label setting which works for you.  E.g.

--x-grid none
--x-grid SECOND:1:SECOND:10:SECOND:10:0:%s

Do similar for the Y-axis.

Try another type of image, perhaps there's a problem in the graph
library.

Try switching off titles and so on (especially if using non-ascii
characters).

Better yet: use "--no-legend" , so that no 'extra' will be in the way.


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