[rrd-users] Re: How does rrdtool behave if I store 5-minute-values for one year?

Thomas Erskine thomas.erskine at sympatico.ca
Thu Jan 30 16:33:11 MET 2003

At 09:41 2003-01-30, Serge Maandag wrote:
 >> So the consolidation is just good for saving disk space?
 >Yes, at least that's the only reason I know.
 >> Am I right, that I would just have to keep 1-year 5-minute-values and
 >I can also get the cf MAX out of it?
 >Almost, if you want average values and max values, you need both an
 >AVERAGE and a MAX rra in you rrd database.

If you have only one RRA, with a step of one (i.e. one input data point 
gives one row in the RRA), there is no consolidation, just normalizing of 
the time.  So you can ask for PRINT:myvar:MAX:... and get a meaningful 
maximum out even though the CF on the RRA is AVERAGE.

However, if you have an RRA or RRAs which do indeed consolidate, then you 
need to have both a MAX and AVERAGE RRA for those time-spans if you want to 
get meaningful mamimums out.  If you have only an AVERAGE consolidated RRA, 
then PRINT:myvar:MAX will be getting you the maximum of the averaged, 
consolidated data.  I.E. the maximums will be low and wrong.  Similarly, if 
you need minimums, you'll have to have a MIN consolidated RRA.

 >-----Original Message-----
 >From: Stephan Harren [mailto:sh at abovenet.de]
 >Sent: Thursday, January 30, 2003 2:29 PM
 >To: Serge Maandag; rrd-users at list.ee.ethz.ch
 >Subject: Re: [rrd-users] How does rrdtool behave if I store
 >5-minute-values for one year?
 >Am I right, that I would just have to keep 1-year 5-minute-values and I
 >also get the cf MAX out of it?
 >Best regards,
 >Am Donnerstag, 30. Januar 2003 13:48 schrieb Serge Maandag:
 >> rrdtool uses the values the rrd holds. For the given time frame you
 >> to graph, it will try to take the highest resolution data.
 >> If you just store 5 minute samples, it will never even think of using
 >> 2 hours average.
 >> 2 hours average samples can only be displayed if your rrd database has
 >> an RRA that averages over 2 hours.
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Thomas Erskine <thomas.erskine at sympatico.ca> +1.613.591.8490

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