[rrd-users] Re: Urk. Help with a little nagging problem I'm having..? Prolly newbie mistake.

Sat Dec 21 12:54:45 MET 2002

On Fri, Dec 20, 2002 at 12:34:29PM -0800, S.D. wrote:
> Here:

[snip most of the script]
[reordered some lines]

1) This script does produce the same result in several versions.
2) RRDtool is probably right (or else many more people report something)

1+2) There must be something wrong with the data

> And here's what I see:
> 
> 1040408352: 4.1812500000e+02 2.7437500000e+01
> 1040408368: 2.6843571562e+08 1.1618125000e+03
> 1040408384: 2.1533750000e+03 3.7287500000e+02
> 1040408400: 4.9168750000e+02 1.3000000000e+01

The problem occurs somewhere at or before time 1040408368

> RRDs::update ("fxp0.rrd", "1040408360:54016412:8335945");
> RRDs::update ("fxp0.rrd", "1040408364:54017607:8336219");
> RRDs::update ("fxp0.rrd", "1040408368:54017213:8336271");
> RRDs::update ("fxp0.rrd", "1040408372:54017500:8336323");

54017607-54016412 = 1195
54017213-54017607 = -394
54017500-54017213 =  287

-394...  Add 2^32:   4294966902

54017607-54016412 =       1195
54017213-54017607 = 4294966902
54017500-54017213 =        287

Compute the rates:

1195       /4 = 298        --> 2.98e2
4294966902 /4 = 1073741725 --> 1.07e9
287        /4 = 71         --> 7.1e1

Ergo: nothing's wrong except your assumption your input data is correct.
When I ask you to do the math yourself I do so for a good reason.

I'm confident that if you're going to compute the consolidated value
for the RRA (or: change the number of PDPs per CDP) you will find an
exact match for the number (but do mind the inevitable rounding errors
when working with floats).

-- 
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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