[rrd-users] How to compute first pdp time?

[Steve Shipway]

The RRDTool PDP (primary data points) are formed after Normalisation.

The Normalisation process adjusts the data back in time to a Step boundary -- IE, if step is 's' and time is 't', then 
( t mod s ) = 0

So, whatever time you submit your sample at, if your step is 5 then the PDP time will be a multiple of 5 (seconds since the Epoch).

Understanding Data Normalisation is a bit more of a job and I can recommend this tutorial -
http://www.vandenbogaerdt.nl/rrdtool/process.php

Steve

Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
s.shipway at auckland.ac.nz
Ph: +64 9 373 7599 ext 86487