[rrd-users] Questions about different RRA`s

[David Schulz]

Hello,

since a while i am digging around the Net to become more clear about  
rrdtool, but i am not making much progress.

My Goal is to graph the Number of Processes on my Server, for the  
last  hour, day, week, month and year. In the beginning i just made  
one big Archive, using

Can someone show me how to best create one such .rrd with multiple  
RRA`s, explain to me the calculations you made to decide on the  
values for the RRA`s? I tried multiple combinations, one -

rrdtool create process_count.rrd --step 60 DS:pc:GAUGE:120:0:U  
RRA:AVERAGE:0.5:1:525960, which is supposed to take one value every  
60 seconds, for one year,

but it appears it is better to split the different required times  
into different RRA`s. I have no idea how to calculate this though. My  
main Problem is to determine the exact Values for the individual  
RRA:AVERAGE:0.5:?:?. I have read that for example this

RRA:AVERAGE:0.5:1:60 should be one hour (1*60*60= 3600 seconds), and  
RRA:AVERAGE:0.5:60:24 should be 24 hours, but how about a week or a  
month for example? Why RRA:AVERAGE:0.5:60:24, and not RRA:AVERAGE: 
0.5:24:60, both should equal a week, right?


I really need a push in the right direction here.
Thanks a lot for any Explanation,
David