[rrd-users] How to change CF in existing RRA

[rrd.4.lgetschel at spamgourmet.com]

I'm new to making my own rrd's. Otherwise I've only used them in Ganglia 
for a few years.

I seem to have created my new rrd file with an incorrect RRA CF, and I'd 
like to correct it without losing my current data.

I created it with: (I saved it just in case this situation came up) <smile>

rrdtool create 
/local1/data/ganglia/local/__SummaryInfo__/cluster_OCI_node_counts.rrd 
--start N --step 180 DS:idle_nodes:GAUGE:600:0:100000 
DS:active_nodes:GAUGE:600:0:100000 DS:busy_nodes:GAUGE:600:0:100000 
DS:assiduous_nodes:GAUGE:600:0:100000  RRA:AVERAGE:0.5:1:480 
RRA:AVERAGE:0.5:7:336 RRA:AVERAGE:0.5:30:480  RRA:AVERAGE:0.5:90:540  
RRA:AVERAGE:0.5:360:480  RRA:AVERAGE:0.5:1080:480

This creates the rrd with 4 DS's collected every 180 seconds (3 minutes) 
and 6 RRA's

If I'm following properly, the RRA CF's are:
1) Keep 1:480 (1*3min * 480 = 1440 min ; so 24Hr of data)
2) I WANTED to keep 1 WEEK next, which should be 7:480 (7*3min=21min; * 
480 = 10080min; so 7 days of data)
      But, I managed to create it as 7:336 which is only about 4.9 days 
of data (this graphs with an odd area view on the graphs I create)(336 
would be used for 30min(10:336) I followed my example too closely I think)
3) Keep 30:480 (30*3min=90min; *480 = 43200min; so 30 days of data)
4) Keep 90:540 (90*3min=270min; *480 = 129600min; so  90 days of data)
5&6 ) similar for 1 year and 3 years of data

I've tried searching in this user archive and on google, but can't seem 
to find whether there is a way to fix this. Is there a way to change the 
file to expand it for the extra values? I thought "rrdtool tune", but I 
don't follow the man page well enough to know if this can do it for me.

If you see a way to fix my mistake I'd really appreciate the details.
Thanks, Lewis