[rrd-users] couple of questions

[A Darren Dunham]

On Wed, Sep 08, 2010 at 08:08:56PM -0700, Ricardo Kleemann wrote:
> How do I go about doing a TOTAL VDEF? That would take care of summing
> up the data points between start/end?

Take a look at the "rrdgraph_rpn"

You create a DEF for your data say something like:

DEF:data=myfile.rrd:data:[blah,blah]

Then with it available as 'data', you can total it with:
VDEF:total_data=data,TOTAL

Then print it with something like
GPRINT:total_data:Total for data is %f

> If you truly want to sum something that is only a subset of the
> graph,
> I'd probably try to construct a CDEF from the original data and have
> it
> nulled out outside the region of interest. Then run TOTAL on it as
> above.

Whoops.  That's more complex than necessary.  I forgot that you can
supply start/end on a DEF.  So you don't have to calculate a separate
CDEF for it, even if your graph is of a different time period.

Presume you have a way to get the start and end of your timeperiod in
there, you'd just do:

DEF:one-month=myfile.rrd:data:AVERAGE:start=$start:end=$end
VDEF:month-total=one-month,TOTAL
[...]

-- 
Darren