Oops, I think I didn't really understand your question... The answer should be: store your percentiles separately (in separate DS-es) and choose the aggregation function that makes most sense in your case, for example the average.
On Sun, Aug 17, 2014 at 8:19 PM, Rafal Gwizdala <rafal.gwizd...@gmail.com> wrote: > There's no 'percentile' consolidation function and it can't be derived > from other statistical functions available in rrdtool, so i think it would > be better to calculate the percentiles before storing them in RRD. > This would of course require storing the data for extended periods of > time, and to calculate 24h percentile you'd have to store 24 h worth of > samples, which could be difficult. > Here's a link to some approximate method which doesn't require you to > store all samples because it's based on histograms. And histograms are an > 'additive' measure, so you can add 24 hourly histograms together to > calculate a daily percentile. > http://techblog.molindo.at/2009/11/efficiently-tracking-response-time-percentiles.html > > I'm also doing some percentile calculations for app performance data, but > I'm using a different approach: a fixed time window of 5 minutes and I > calculate multiple measures for that period: average, median, 95th, 98th > and 99th percentile. These measures are then writtend to a RRD file every > minute. > > > > On Sun, Aug 17, 2014 at 6:57 PM, Peter <pspieg...@gmx.de> wrote: > >> Hi, >> I use rrdtool to store measurement data in rrd files used by Cacti. >> The measurement data have an interval of 50 ms. >> I need Average, Max, 99% and 5% Percentil. >> I used the lowest possible step size in the rrd files:1 second. >> For Average & Max I created separate rrd files with RRAs: >> 1s: for a week , 1 min: for a month , 5 min: for a year >> My program now calculate every second the max & avg values and updates the >> rrd files. >> This works fine, also in Cacti. >> >> Is a solution possible for the percentiles? >> The prefered solution would be: based on the 50 ms data. >> But a 50 ms step size is not possible. >> >> And percentiles of small intervals are not so interesting. >> I could calculate the percentiles in my program for intervals >> 5/10/15/30/60 min, 3/6/12/24 hours >> >> But how should I define the rrd file and update the rra for this >> intervals? >> Now the RRA are calculated from rrdupdate by the given consolidation >> function. >> Or can I set each RRA manually? >> >> >> And Cacti need also a consolition function to create a DEF for rrdgraph , >> i.e. for MAX >> DEF:a="/Data/rrd/DataMax.rrd":"DATAMAX":MAX \ >> Which RRA use rrdgraph (called by Cacti)? >> If rrdgraph use always the RRA with the smallest matching intervall, so I >> can use LAST or MAX (for 99%), MIN (for 5% ). >> >> >> Peter >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> -- >> View this message in context: >> http://rrd-mailinglists.937164.n2.nabble.com/Save-and-Calculate-Percentil-tp7582357.html >> Sent from the RRDtool Users Mailinglist mailing list archive at >> Nabble.com. >> >> _______________________________________________ >> rrd-users mailing list >> rrd-users@lists.oetiker.ch >> https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users >> > >
_______________________________________________ rrd-users mailing list rrd-users@lists.oetiker.ch https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users