[rrd-users] RRDs Coding Question - Dynamic Multiple RRD Data Sources
linux at thehobsons.co.uk
Wed Sep 26 16:03:29 CEST 2012
Wesley Wyche wrote:
>So, since you say an Unknown (NaN) plus some value equals Unknown again
>then I can't use this in this way. These values in the various
>node's rrds must be merged together to represent a single snapshot
>of what is happening.
See my earlier post - you can handle this with a bit of RPN
>Makes absolutely no sense (to me anyway).
Makes complete sense - add <something unknown> to a number and the
result cannot be anything other than unknown. Different users will
want different things - you may want to just ignore the unknown data
(see the RPN I posted earlier), others may wish for the whole lot to
be unknown because that's what *their* data means.
Also, note that the same applies when stacking data - if something is
unknown, then anything stacked on top of it in a graph will also not
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