[rrd-users] Help - probably a really stupid mistake somewhere ...

A Darren Dunham ddunham at taos.com
Tue Aug 17 21:55:43 CEST 2010

On Tue, Aug 17, 2010 at 12:11:55PM -0700, Philip Peake wrote:
> In some examples, I find multiple CFs being defined. For example:
>     rrdtool create test.rrd --start N --step 5 \
>     DS:value:GAUGE:10:-1:101 \
>     RRA:AVERAGE:0.5:1:30 \
>     RRA:AVERAGE:0.5:5:6
> So we are keeping two averages, averaged over different periods.
> When graphing, how do I select which of these AVERAGEs to use?

See this section in the graph document.

$ man rrdgraph
       Time range
           [-b--start time] [-es--end time] [-Sb--step seconds]

           The start and end of the time series you would like to display,
           and which RRA the data should come from.  Defaults are: 1 day ago
           until now, with the best possible resolution. Start and end can be
           specified in several formats, see AT-STYLE TIME SPECIFICATION and
           rrdgraph_examples.  By default, rrdtool graph calculates the width
           of one pixel in the time domain and tries to get data from an RRA
           with that resolution.  With the step option you can alter this
           behaviour.  If you want rrdtool graph to get data at a one-hour
           resolution from the RRD, set step to 600. Note: a step smaller
           than one pixel will silently be ignored.

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