defaults.inc.php:$config['rrd_rra'] = "

  RRA:AVERAGE:0.5:1:2016

  RRA:AVERAGE:0.5:6:2976 

  RRA:AVERAGE:0.5:24:1440

  RRA:AVERAGE:0.5:288:1440 ";

So for a step of '300' (5 mins) we have

 1 PDP @ 300seconds = 5 mins (x 2016) = 7 days of 5 minute intervals

 6 PDPs @ 300seconds = 30mins (x 2976) = 62 days? 2 months? (of 30min averages)

 24 PDPs @ 300seconds = 2 hour (x 1440) = 120 days (of 2 hour averages)

 288 PDPs @ 300 seconds = 24 hours (x 1440) = 4 years? (of 1 day averages..)

Cheers,