Add "decade" RRA to existing configuration

Hi,

I'd like to add a "Decade (1 Week Average)" to the existing data sources.
I've gone through the archive here, the manual, and other places
(collectd), and found a lot of information about extending existing RRAs
in an RRD, but I just want to append an RRA. Nothing jumped out at me;
apologies if I just missed it.

The "add_rra.sh" tool[1] seems close, and I might need to instrument
something like it to accomplish this, but I'm not sure what the rest of the
changes that I need to make to Cacti are.

It looks like I need to add the new RRA to the Data Templates as well as
the RRDs?

Anyway, I'm using the stock RRAs, and just want to add this new one,
have it show up in existing graph collections, etc, etc. I'm not picky
about the stored data, I just want to have a relative sense of things
spanning back for more than a year. Who know, I might want to do this
again for "Century (1 Month Average)" when I get bored. ;)

I created the new RRA as:

    name: Decade (1 Week Average)
    consolidation: AVERAGE & MAX
    x-files factor: 0.5
    steps: 2880
    rows: 1040
    timespan: 314496000

I *think* this is correct for what I'm after, but now I'm stuck trying to
figure out how to attach this new RRA to the needed Data (and Graph?)
templates, and how to inject this into the existing RRDs. It would be
_nice_ to have the last year show up in the new Decade RRA, but I could
live with it starting fresh. I'd really like to avoid just losing all the
existing RRDs, though.

Thanks for any pointers or help,

-Kees

[1] https://github.com/octo/collectd/blob/9e46dabef33262ba5d52973d99889b4a32e781c0/contrib/add_rra.sh

-- 
Kees Cook                                            @outflux.net

------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/