[Xymon] top ten list of servers wrt cpu load

[Jeremy Laidman]

On 19 March 2013 06:55, Steve Holmes <sholmes42 at mac.com> wrote:

> So, I'm looking it writing a script to mine the rrd or history data from
> the Xymon server to produce the list he wants. He is also interested in the
> top disk I/O numbers, too, but I'm focusing on load average for now.
>

Sounds useful.  I've not seen anything that does this already.


> close so I was looking at rrdtool fetch. However, this is cumbersome and,
> frankly I'm not understanding the data I'm getting back (for example
> 1.22749483e+03 seems to be 12.27... when I compare it to the graphs, so the
> e+03 seems to really mean *10^1, right?)
>

Nope, 1.227+03 means 1227.  However, sometimes there is an adjustment
applied, that's not always obvious.  For example, my understanding is that
the load average (in la.rrd) is recorded after multiplying by 100, which is
an artefact of the BigBrother legacy, because floating-point comparisons
were difficult to implement in a generic shell script that had to run on
any *nix platform.  The BigBrother data collector would chop everything
after two decimal places, then strip the dot out, thus providing a load
average factored up by 100.  You can tell this is what's happening in Xymon
by looking at the [la] entry in graphs.cfg, or to save you looking it up:

        DEF:avg=la.rrd:la:AVERAGE
        CDEF:la=avg,100,/

So the graphs.cfg entry scales it back down before graphing.

Similar adjustments are made for things like interface load and TCP/IP
stats, where bytes-per-second are converted to bits-per-second.  Again, the
graphs.cfg file often gives you a clue as to what's going on.

J
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