[rrd-developers] Re: documentation: templates for ansychronous up date

Jake Brutlag jakeb at microsoft.com
Fri Feb 16 23:16:22 MET 2001

> whenever there is an update to an .rrd ALL the datasouces receive
> an update if a datasource is not updated because it is not in the
> template, rrdtool assumes that the datasource is unknown and
> updates it accordingly ...

This is a reasonable restriction. My only suggestion is that there should be
a comment to this effect in the rrd update doc file.

> In any event, there is a problem for 'caculated datasources' in
> that respect. The --step of a CDEF is calculated from the steps of
> all DEFs used withing the CDEF rpn. This means a CDEF-DS would
> probably have to live in its own rrd or in a rrd with compatible
> step ...

The 'first cut' solution here is to restrict the calculated datasources to
only depend on data sources within the same RRD file, as all data sources in
the same file have the same step size.


Jake Brutlag
Network Analyst
Microsoft WebTV 

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