RRD Graphing configuration

Bill Richardson wrichardson at llbean.com
Mon Aug 11 20:57:28 CEST 2008

Thanks for the help.. I think i'll try the rrdcreate and let you know.
On Mon, Aug 11, 2008 at 8:53 AM, Bill Richardson <wrichardson (at)

>  I have looked high and low for a way to change how custom rrd's are
> created in hobbit.
> I have created a custom script to graph and have 2 problems that I
> like to figure out.
> 1.) I would like to change the step from 300 secs to 60 secs in the
> and run the script ever 60 secs instead of 300 secs. "The default rrd
> behavior is set to 300 secs"
> 2.) I would like to get the true values not average. The problem is I
> have data that I want to graph that can range from 0 to 5  "thats 0,
1, 2,
> 3, 4  or 5" and the graph shows average so my graphs come out with
> like 6m "6 milli" for a true value of 2 and so on. The problem is the
> data will sit a 0 for an hour or more and then go to 1 or 2 for just
> sample. Average is not the right choice and I cant get the true
figures I 'm
> looking for.
>  Seems like the way to do this is in the hobbitserver.cfg. I added the
> following to the hobbitserver.cfg
> NCV_testgraph="test1total:GAUGE,test2total:GAUGE,test3total:GAUGE"
>  What other values can you pass to rrd other than GAUGE? Can I set a
> to say 60 instead or 300 and can I change the default behavior of
> something else that may work for my above example? The rrd docs are
> clear on this.
> Early on I was thinking that maybe I could fix the AVERAGE problem
with a
> change to the hobbitgraph.cfg but this is what I found:
> The hobbitgraph.cfg does not have any effect on how rrd file is
created. I
> deleted the testgraph.rrd made the changes to hobbitgraph.cfg and no
> You cant see the graphs if you use anything but AVERAGE after changing
> hobbitgraph.cfg. It looks like the *.rrd's are created by default
> and you just edit the hobbitgraph.cfg to view whats already built. I
need to
> figure out how to change the way the rrd's are built and its not thru
> the hobbitgraph.cfg.

If you're comfortable about fooling with the source, there are a couple
places where you can make changes to achieve what you want:

hobbit-4.2.0/hobbitd/do_rrd.c contains these definitions:

     static char rra1[] = "RRA:AVERAGE:0.5:1:576";
     static char rra2[] = "RRA:AVERAGE:0.5:6:576";
     static char rra3[] = "RRA:AVERAGE:0.5:24:576";
     static char rra4[] = "RRA:AVERAGE:0.5:288:576";

BUT - if you change those, I think *every* new rrd created by Hobbit
pick up the same changes.

do_rrd.c also includes a bunch of test-specific files, one of which is
hobbitd/rrd/do_ncv.c.  That contains the code that examines NCV_xxx and
up DS entries to match.:

         sprintf(dsdef, "DS:%s:%s:600:0:U", dsname, dstype);
         sprintf(dsdef, "DS:%s:DERIVE:600:0:U", dsname);

A bit further down it copies in the above rra1 - rra4 definitions.  So,
could change the hardwired DS and RRA values in do_ncv.c, but ONLY if
don't have any other NCV that would  need to be different...

Another way to get towards what you want would be to hand-create the
Hobbit won't overwrite an existing rrd.  I think the rrdcreate would
something like this:

     rrdtool create testgraph \
        DS:test1total:GAUGE:60:0:U \
        DS:test2total:GAUGE:60:0:U \
        DS:test3total:GAUGE:60:0:U \
        RRA:AVERAGE:0.5:1:576 \
        RRA:AVERAGE:0.5:6:576 \
        RRA:AVERAGE:0.5:24:576 \

I haven't tried this myself, but I think Hobbit would be able to do

Ralph Mitchell

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