[rrd-users] Getting Max/Min values from Average RRDs?

[Yannick Marquet]

Hello,

> Hi RRD-users,
>
> I have RRD-files with 5 years of data captured every 5 minute.
> 1 DataSource per file that is defined as AVERAGE , and I have no 
> consolidation of the data.
> We want to be able to go back and look at the full resolution at any time.

So juste one RRA needed.
> We update around 800k RRD-files on a single server every 5 minutes.
>
> I want to export the data with some consolidation - say daily, weekly, 
> monthly average numbers and want to be able to show the maximum and 
> minimum I had during that consolidated time-slot. (not the total 
> max/min of the final consolidated values).
rrdtool export may be a solution (for consolidate data "on the fly"). 
But you want to calculate how much rows needed for param "--maxrow"

this solution works for rrdtool graph, but i don't try with rrdtool export
(maybe documentation is outdated, this syntax can be found only here : http://oss.oetiker.ch/rrdtool/doc/rrdgraph_data.en.html)

You can param step in DEF for exporting data.

DEF:ds0b=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=1800

For max/min  you can use "reduce" parameter data to change how data is 
reduce :

DEF*:*/<vname>/=/<rrdfile>/:/<ds-name>/:/<CF>/[:step=/<step>/][:start=/<time>/][:end=/<time>/]*[:reduce=**/<CF>/**]**
*

ex :
DEF:ds0bdailymax=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=86400:reduce=MAX
DEF:ds0bdailymin=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=86400:reduce=MIN
DEF:ds0bdailyavg=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=86400

DEF:ds0b30daymax=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=2592000:reduce=MAX
DEF:ds0b30dayymin=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=2592000:reduce=MIN
DEF:ds0b30dayavg=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=2592000

DEF:ds0b365daymax=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=31536000:reduce=MAX
DEF:ds0b365daymin=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=31536000:reduce=MIN
DEF:ds0b365dayavg=/home/rrdtool/data/router1.rrd:ds0:AVERAGE:step=31536000


> I can implement this externally using fetch - and then do the max/min 
> calculations in each bucket, but I assume that this is the same thing 
> that RRD-tool do internally whenever consolidated DS are updated.
> How can I use these functions when exporting (and graphing) data.
> When graphing data the consolidation-slots are calculated based on the 
> data-points and available graph-resolution, so it would be nice to 
> just say give me the max and min as an value-array just like in a CDEF.
>
> I have searched and searched, and made many unsuccessful tries with 
> different VDEF, CDEF combinations - but no luck.
>
> Any ideas?
>
> /Johan
>
>
> -- 
>
> *Johan Elmerfjord* | Sr. Systems Administration/Mgr, EMEA | Adobe 
> Systems, Product Technical Operations
>
>
>
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Dears,

Yannick
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