[rrd-users] Re: MAX doesn't work as expected: peaks are filtered

[Cristian Ghezzi]

Thank you for your prompt answer and sorry for sounding so negative.
I actually like rrdtool and I'm using it in my work.
Still I find it counter-intuitive sometimes, as shown in my example.
I would expect rrdtool to gather different kinds of PDPs to be used by 
different kinds of CFs, so that I could have one database with 2 RRAs, 
one of them using AVERAGE and the other one using MAX, with a step of 
300, and everything working properly because one PDP would hold the 
average value to be fed to the first RRA, while the other PDP would hold 
the maximum value to be fed to the second RRA.
Using "--step 1" would not be the best solution, but just a hack.

Regards


Cristian


P.S. I've put the nice words on top this time :-)



Alex van den Bogaerdt wrote:

>On Sun, Aug 15, 2004 at 03:43:08PM +0200, Cristian Ghezzi wrote:
>
>  
>
>>It appears that all values inserted in the database within the last STEP 
>>period are always averaged when creating a PDP, even when I'm going to 
>>use the value in a MAX RRA, thus creating spurious values.
>>    
>>
>
>  
>
>>This means that if I insert more than one value within a step, I will 
>>not find the MAX of those values in the database, but an average value 
>>which will always be lower than expected.
>>    
>>
>
>So, you are going to have "--step 1" and all is well.  Adjust your RRA
>steps per CDP to your liking.
>
>  
>
>>- What happens is clearly wrong: the value of 500 inserted in the middle 
>>of the previous STEP, which is an absolute maximum for the whole period, 
>>has been smoothed down to 450.
>>    
>>
>
>This is not wrong.  This is expected behaviour. You can control this
>process by adjusting step sizes and steps.
>
>  
>
>>Am I doing something wrong?
>>    
>>
>
>Nice order...
>"rrdtool is wrong, rrdtool is bad, rrdtool sucks, Am I doing something wrong?"
>
>Alex
>  
>

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