[hobbit] RRA definitions for rrds?

[Henrik Stoerner]

On Mon, Feb 28, 2005 at 04:09:52PM -0800, Bruce Lysik wrote:

> So I've gotten some new data being graphed in Hobbit.  However, I've
>  got a request to set it up in such a way that I don't lose
>  granularity.  Basically I want to be able to define the rrd with 2
>  years worth of data points.  Is such a thing possible in Hobbit?

Not right away. The Hobbit graphs are fixed at 576 data points per
period, giving you 48 hours of data for the most detailed graph.

If you must do this, you will have to code a small piece of C code
like the ones in hobbitd/larrd/ to manage your data. In each of these
modules, there is a declaration of parameters used to create the RRD
file; these are defined like this:

static char *bbgen_params[] = { "rrdcreate", rrdfn, 
			   "DS:runtime:GAUGE:600:0:U", 
			   rra1, rra2, rra3, rra4, 
			   NULL };

The "rra1", "rra2", "rra3" and "rra4" are pointers to the actual
definitions of how many data points to store and how they are averaged
out over a period; the first one is the one that holds the most
detailed data:

static char rra1[] = "RRA:AVERAGE:0.5:1:576";

So with a bit of C experience and some knowledge of how RRDtool works,
it would be possible to do. You'd need some 7 MB of storage per item
you monitor.

I'd suggest having a good read of the rrdcreate man-page.


Regards,
Henrik