[rrd-users] Questions of new user

[Alex van den Bogaerdt]

----- Original Message ----- 
From: "Simon Hobson" <linux at thehobsons.co.uk>
To: <rrd-users at lists.oetiker.ch>
Sent: Sunday, December 06, 2009 10:37 AM
Subject: Re: [rrd-users] Questions of new user


> rrd-users at ficos.de wrote:
>
>>  > 2. Example:
>>>
>>>  i have --step 300
>>>  If i will update often, then 300 sec (for example every 10 seconds)
>>>  what will be? Which data is stored?
>>
>>if you update more often than required for you step size, the data will be
>>aggregated using the aggregation function you've chosen (MIN, MAX,
>>AVERAGE etc)
>>so either the smallest or the highest or the average of the values
>>will be stored.
>
> No, the aggregation functions are NOT used for sub-step updates.
>
> See Alex's tutorial on rates and normalising - it's all explained well 
> there.
> http://www.vandenbogaerdt.nl/rrdtool/



Actually I did not really describe sub-interval updates.  And I don't know 
from the top of my head. I'd have to look in the sources to see what really 
happens when you do that.

I'd probably have step==1, and 300 steps per step in each of 
{MIN,MAX,AVERAGE} RRAs. That results in one value per five minutes, with 
aggregation as described above.

For the OP:

Those tutorials are probably going to help you. Start with "the" tutorial.

Experiment a lot.  Create a database, update it, fetch the data and see if 
you can predict what rrdtool is going to show you.

HTH
Alex