[rrd-users] More observations and questions on COUNTER

Philip Peake philip at vogon.net
Sun Oct 24 20:00:24 CEST 2010

On 10/24/2010 9:58 AM, Simon Hobson wrote:
> Philip Peake wrote:
>> So you are saying the rate is always per second?
>> I thought it was rate per <sample period> ??
> It is always <somethings> per second.
>> So a value stored at the exact end of a sample period would be equal to
>> the value presented.
> IF (and only if) you feed in updates exactly on every step boundary 
> (and remembering that the refernce is always midnight 1st Jan 1970 
> (unix epoch), then yes, the value stored for that step will be what 
> you feed in - subject to any conversion required (in this case 
> subtracting the previous counter value to get the difference). Under 
> any other circumstance you will get normalisation.
> This is a commondly asked question, and the simple answer is that RRD 
> Tool is not designed to store original values - it is designed to 
> store rates. Any fudges to make it store accurate values are just 
> that. Also, rates are always stored as a floating point number.
> See Alex's tutorial on normalisation and consolidation at 
> http://www.vandenbogaerdt.nl/rrdtool/

So if you look at the data I present to RRD, you will see that it is on
30 second boundaries, so I would expect the stored value to be the same
as the presented value -- no ?

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