[rrd-users] Re: Help understanding rrdtool

Alex van den Bogaerdt alex at ergens.op.het.net
Thu May 19 00:40:13 MEST 2005

On Wed, May 18, 2005 at 11:21:33AM -0300, Maicon Stihler wrote:

> Im a newbie on rrdtool and Ive been reading the tutorials on the
> website, but Im having some trouble to understand it.
> I want to make graphs about CPU utilization, lets say:
> 1 Day - five minute average
> 1 Week - 30 minute average
> 1 Month - 2 hour average
> 1 Year - 1 day average
> Data is read every five minutes.
> I created a rrd archive and succeeded creating a 1 Day graph with the
> following RRA:AVERAGE:0.5:1:288, when I tried to add an RRA for the
> weekly graph I messed it up.

RRDtool cannot add RRAs by itself.  There may be external tools 
that do this, I don't know.

You need to think what you want (and you already did) and then
create all RRAs in one "rrdtool create" command.

The newly created RRD file will be empty, your data destroyed.
If you absolutely cannot live with this, better backup the file
right now (and each day from now on) until you understand how
you can perform some voodoo and import the saved data into a
new file.

> Does I need to separete the RRAs in diferent archives, so when I try
> to generate the graphs I have only one RRA to get the data from?
> otherwise, if I put all the RRAs in only one archive how do I teel the
> "rrdtool graph" wich RRA to read?

RRDtool graph will select the most suitable RRA for your query.
If you want data from the last hour, it will select the RRA that
contains five minutes per row.  If you ask for the last year, it
will select the RRA that contains data at one day per row.

> All the graphs are averages and of type gauge, except the daily graph
> that averages only one sample.

I really don't see what you're getting at here.  You seem to think
"average" and "gauge" are of the same class.  They're not.  Please
reread the tutorials and manuals about this, or rephrase your remark.


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