[rrd-users] HELP I dont understand RRA's

[tony at specialistdevelopment.com]

Ah very cool! Makes more sense now, will try and get it sorted to get  
it graphing.

Thanks :)

Quoting mailinglist at atlaware.com:

> Hello,
>
> I had your same problems few days ago and finally doing some tests i  
> think i understood how RRAs work (but yet I'm not so sure).
> I'll try to explain you how i think it works with an example (the  
> archive i had to do):
>
> rrdtool create snr.rrd    \
> --start N --step 1800 \
> DS:ds0:GAUGE:3600:0:40  \
> DS:ds1:GAUGE:3600:0:40  \
> RRA:MIN:0:1440:12 \
> RRA:MIN:0:48:30 \
> RRA:MIN:0:2:168 \
> RRA:AVERAGE:0:1440:12 \
> RRA:AVERAGE:0:48:30 \
> RRA:AVERAGE:0:2:168 \
> RRA:AVERAGE:0:1:48 \
> RRA:MAX:0:1440:12 \
> RRA:MAX:0:48:30 \
> RRA:MAX:0:2:168
>
> Ok you already know what the first 4 lines mean, but the --step  
> number is important to organize the RRAs since it means how often  
> you are going to update the archive (in my case every 1800:60 =  
> 30minutes).
> Then i make 3 RRAs which will store weekly informations every hour  
> with MINIMUM, MAXIMUM and AVERAGE value
> RRA:MIN:0:2:168
> RRA:AVERAGE:0:2:168
> RRA:MAX:0:2:168
> The first number "0" means that if one update gives an UNKNOWN  
> number even the MIN/AVG/MAX will be unknown. This value can be a  
> number between 0 and 1, if you put 0.5 it means that 50% of the  
> updates can be unknown and still it will calculate the MIN/MAX/AVG  
> with the known values.
> The second number "2" multiplied with "--step" means that you want  
> to store the data every 1800*2=3600 seconds which is 1 hour.
> The third number "168" multiplied with the last result (1 hour) is  
> the life of that archive. 168 hours : 24 = 7 days. Every 7 days the  
> archive will start over again overwriting the previous 7 days data.
>
> Now the last RRAs:
> RRA:MIN:0:48:30
> RRA:AVERAGE:0:48:30
> RRA:MAX:0:48:30
> Means 30 mins * 48 = store data every 24 hours for (30) one month
>
> And:
> RRA:AVERAGE:0:1440:12
> RRA:AVERAGE:0:1440:12
> RRA:MAX:0:1440:12
> 30mins * 1440 = store data every 720 hours (720:24=30 days) for (12)  
> one year.
>
> And:
> RRA:AVERAGE:0:1:48
> store data every 1*30 = 30 minutes for 48 = 24 hours.
>
> I hope I didn't teach you something wrong and that someone else will  
> answer too :)
> By the way this is the graph i made with that archive:   
> http://mrtg.atlaware.com It's the SNR one.
> Sorry for my English!
>
>
> Il 25/01/2010 12:06, tony at specialistdevelopment.com ha scritto:
>> Hi Guys,
>>
>> Im really sorry to ask this as im probably being very stupid...Im new
>> to RRD tool and think it is amazing, im trying to write a set of Perl
>> scripts to monitor my traffic in and out...
>>
>> I have followed tutorials, examples etc, but to finally get my head
>> around it im trying to do it on my own, but i come unstuck, when it
>> comes to RRA's in the RRD creation.
>>
>> Can anyone explain in really, really simple terms what they are?
>>
>> Thanks for any replies I get.
>>
>> Tony
>>
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>>
>
>