[collectd] Suppress RRA Timespan ?

[Flyinvap]

Hi,

It's possible to add rra timespan with the rrd plugin but is it
possible to suppress some ?

I configured the plugin to keep 4300 rows per RRA. RRD files rised a
litte ;-). I just want to keep files during some weeks, so one month
and one year are useless and take some bytes on the disk and some
processing.

I can't see the option in the man. I may need to alter the rrd files
after they are created ?

Regards.

-- 
Flyinvap