[rrd-users] [rrd] Can't I turn off data smoothing for GAUGE?

Simon Hobson linux at thehobsons.co.uk
Thu Aug 19 17:10:42 CEST 2010

Pablo Sanchez wrote:

>  > There is virtually no way in the real world that a data source and
>  > rdd will by synchronized to the nanosecond.
>The synchronization doesn't have to be as high a resolution as to the
>`nanosecond' (I realize you're being facetious).
>I'm currently testing gear and my `step' is set to 60s.  The script
>I've written computes its `wake-up' to always be at the start of the
>next minute.  It takes about seven seconds to query the device so I
>end up updating a value seven seconds after the top of the minute.
>Next, my process sleeps until the top of the next minute.
>I guarantee one metric collected per step.

Tobias Oetiker wrote:
>  > Tell me how I synchronize a data source to RDD's concept of sample times?
>>  Actually, what is RDD's concept of sample times? How does it determine
>>  the start?
>>  I would assume time starts with the first entry (or is it the time it is
>>  created?).
>the time slots are aligned to the epoch (1.1.1970).
>The sample interval is always from the last update to the curent

And something no-one has mentioned so far - you do not have to use 
"now" in your update statement. Taking the example above, you can 
compute what the time was at the last integral multiple of "step" and 
use that. Eg, if you end up calling rrd tool at 00:00:07, then 
instead of being 7 seconds late, you could use a timestamp of 

Obviously you may some some precision in timing, but if your primary 
concern is to avoid normalisation then overall you gain.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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