[rrd-users] Re: No graphic line's show up

[Alex van den Bogaerdt]

On Fri, Apr 25, 2003 at 04:18:23PM +0200, Sjaak Nabuurs wrote:

> What could be wrong ?
> I guess somthing wrong with timing

Yup.

Two problems, both time related.


> # generate example in a FORNEXT LOOP This works fine showed a nice graph
> #     for ($t=$start; $t<$start+300*300; $t+=300){
> # RRDs::update $rrd, "$t:".(sin($t/3000)*50+70). " $t:".(sin($t/100)*50+30).
> " $t:".(sin($t/3000)*30+300).
> " $t:".(sin($t/3000)*50+10). " $t:".(sin($t/200)*50+10). "

You are using explicit times.  No problem, as long as you remember
what you're doing.

> RRDs::graph "$pngfile",
>   "--title", "HTTP data transfer, loadbalancing router VSM.",
>   "--vertical-label", "Waardes in Mbits",
>   "--start", "now",
>   "--end", "start+1d",

You are graphing from "now" to "now+1d".  This is wrong twice:

1) There will never be any data available for intervals in the future
2) You are not graphing the interval that you set using your update commands

"--start" defines the left hand side of the image
"--end" defines the right hand side of the image
Time flows from left to right.

HTH
Alex
-- 
Much of what looks like rudeness in hacker circles is not intended to give
offence. Rather, it's the product of the direct, cut-through-the-bullshit
communications style that is natural to people who are more concerned about
solving problems than making others feel warm and fuzzy.

http://www.tuxedo.org/~esr/faqs/smart-questions.html

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