Re: Add "decade" RRA to existing configuration

1) With plain rrdtool, it is mot possible to add a new rra to an existing rrd
file. You may use some tool from the contrib section, instead. Or create the rrd
files from scratch.
2) When defining a new rra in Cacti, this will apply to newly created rrd files
only, due to the restriction above.
3) When defining an rra, it is important to know, which base polling interval is
in use. E.g. the result will differ for e.g. 1 min polling or 5 min polling
4) The "timespan" in fact is not an rrdtool parameter. It is used by Cacti to
define the timespan of the graph that will be created when clicking on e.g. a
tree view graph. For each timespan defined (by default: 4 timespans), you will
see a new graph, then; each of them spanning the defined timespan.

It is recommended to plan the rra design carefully as it is not possible to
easily change it back and forth.
It is planned and at least partly coded (but not ready for release in the next
months) to introduce some rra add/delete features for Cacti, based on XML
manipulation functions.
Reinhard

On 13.05.2012 03:59, Kees Cook wrote:
> 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
> 

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