Split the 'Samples' setting

[mlang38]

I use Graphite to store temperatures from sensors once every 15min. As I understood, the "samples" setting is used for 2 purposes :

• how many samples the moving average is based upon
• how far ago processor.php searches for data in the graphite render request using the "from" parameter

I think the two purposes should be considered separately. With my 15min retention frequency, I must set "samples" to at least 15 to be sure to find data to check. But therefore I'm stuck with a moving average of 15 samples, that I don't want.

[mlang38]

The problem seems to be more critical than expected. Since the movingAverage function search for 15 points within 15min, or 30 points in 30min etc... it won't work for every one who use graphite with low frequencies data, like me, with 1 point every 15min.

[twinforces]

The graphite solution to this is to use a counter. Then you make two lines, the original counter and the time shifted counter. Take the difference, and you have a window showing the number of occurrences in a sliding window across your time shift. We use this for a processing step that runs every 4 hours, we alert on too many errors in any 24 hour window.

That said, the Tattle feature we would like would be to set how often to check.

[g76r]

Hi, I've just merged #52 that should solve the issue by replaceing samples with minutes in moving averages.