[rrd-users] Re: Questions

On Mon, Nov 20, 2006 at 03:07:33PM -0800, Jonathan Daugherty wrote:

> - What is the difference between GAUGE and ABSOLUTE data sources?
> Considering my use case, I can't tell from the man page, based on
> my use case:
>
> GAUGE is "for things like temperatures or number of people in a
> room or the value of a Redhat share."
>
> ABSOLUTE is "is for counters which get reset upon reading."
>
> I'd like to count, say, the number of new IP addresses in my apache
> log each hour, or the number of new accounts on a web site. Which
> one is best? And is the choice of GAUGE or ABSOLUTE important when
> you want to use AVERAGE RRAs?

http://www.vandenbogaerdt.nl/rrdtool/process.php
under "Transform to a rate".

> - If I have an RRD with a Gauge DS of 5-minute resolution, is there a
> way to compute (and store in an archive) the sum of all values from
> the DS over, say, a one-hour or one-month period?
>
> I guess I could have archives of one-hour and one-month resolution
> and compute the totals externally. The TOTAL RPN function seems to
> do what I want, but only at graph-rendering time, and its domain is
> the entire graphed data set. I just want to feed small samples
> into RRD and find out later what happened over the course of a
> particular week, month, or year.

They aren't values, they're rates: "x" per second.

If you use "rrdtool graph" but don't actually use graph elements (such
as LINE, AREA but also GPRINT) then you can use PRINT to print a value
which you can use in a script (or read from the output).

The average of an hour's worth of data, multiplied by 3600, is the
amount of "x" in that hour.

If this didn't answer your question, please elaborate and give an
example.

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

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