[mrtg] Increasing the length of saved data

[Max Clark]

Hi all,

We are using MRTG + RRDtool and would like to increase the resolution
of data in the system. Instead of storing five (5) minute detail data
for the default we would like to store this data for a minimum of
three (3) months (maybe as much as six). How do we make this change so
MRTG will autocreate the RRD files in this manner?

Thanks,
Max