[rrd-users] Fwd: Percentile consolidation

[Donovan Baarda]

On 27 October 2015 at 18:17, Donovan Baarda <abo at minkirri.apana.org.au>
wrote:
[...]

> This thread made me look at the RRD docs again and I discovered it now
> supports DS's of type COMPUTE. That means it can already support
> calculating value^2 as another DS, making it possible to do this;
>
> rrdtool create traffic.rrd \
>    --start now --step 1m \
>    DS:rate:COUNTER:2m:0:1000000 \
>    DS:rate2:COMPUTE:rate,rate,*
>    RRA:AVERAGE:0.5:1m:8d \
>    RRA:AVERAGE:0.5:1h:64d \
>    RRA:AVERAGE:0.5:1d:2y \
>
> and then get an approximate 95 percentile in your graphs by calculating
> 2*stddev like this;
>
> DEF:rate=/home/rrdtool/data/traffic.rrd:rate:AVERAGE
> DEF:rate2=/home/rrdtool/data/traffic.rrd:rate2:AVERAGE
> CDEF:variance=rate2,rate,rate,*,-
> CDEF:stddev=variance,SQRT
> CDEF:95ptile=stddev,2.0,*
>

Doh! I forgot to add the average. That last line should be;

CDEF:95ptile=rate,stddev,2.0,*,+

-- 
Donovan Baarda <abo at minkirri.apana.org.au>
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