On Mon, Mar 18, 2013 at 6:27 PM, Jeremy Laidman <jlaidman at rebel-it.com.au>wrote:
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
Attached is the perl script I came up with. It serves my purpose and might be useful to someone. $fudge will have to be expanded for other measures. I may do that if someone here at Purdue requires it. Otherwise have at it.
Steve Holmes Purdue