[hobbit] CPU Graphs

[Henrik Stoerner]

On Tue, Mar 06, 2007 at 04:01:58PM -0600, James Wade wrote:
> I raised a question a month ago about less averaging
> on the CPU graph. 
> 
> In the hobbitclient-sunos.sh I changed the vmstat to
> take 15 second samples.

That won't change anything, unless you also re-created the "vmstat.rrd"
files by hand and changed the RRD "step" setting so it knows that
updates appear with 15 second intervals. If you haven't, the extra
measurements are simply ignored.

> I have another question, Does the graph view average
> the datapoints as well? Can I have it give me just the
> raw datapoints in the graph?

RRD never stores raw datapoints - it is always normalized. You cannot
really feed updates to Hobbit or the RRD files at *exactly* the interval
you should; there will always be a slight jitter - maybe the interval
between two updates are 14.5 seconds, or 15.3 seconds, or even 17
seconds (if your system is busy). RRDtool therefore takes your data
and calculates what it would have been if you had been feeding the
update at exactly 15 second intervals - and this calculated value is the
one that is stored in the RRD file. See the "RRD Tutorial" at the RRD
website, http://oss.oetiker.ch/rrdtool/tut/rrdtutorial.en.html
The paragraph titled "Data Resampling" explains this.

And no, the graph view doesn't process the data in any way - all of that
is handled by RRDtool when the data is stored in the RRD file.


Henrik