[rrd-users] Direct RRA updates

Simon Hobson linux at thehobsons.co.uk
Sun Nov 13 18:54:13 CET 2011

krcmar at datinel.cz wrote:

>I have the following idea: I would like to store statistics of a
>network interface (throughput in megabits per second) using RRD. Say
>the appropriate DS would be updated in minute intervals (it would have
>"step" set to 60 seconds). But the software which gathers the stats is
>able to read counters more frequently (for example once in every
>second), so it does not get only total (average) throughput for whole
>60 seconds, but also minimum and maximum throughput withing the 60
>seconds (with 1 second time slot). Is there any possibility to store
>this information to the RRD as well?

You can update as often as you like, the data will get normalised 
into the periods you specify with step. You will not get any more 
detailed information, ie it will not take the max of one of your one 
second updates, only of the 60 second (in your example) mormalised 
time slot.

>I know there is still possibility to create three RRD files, one for
>MIN, the second for MAX and third for AVERAGE, since all DSes in a
>single file share all RRA definitions, but is there a better solution?
>(Also, I don't want to simply set step to 1 second and update the file
>60 times per minute).

That is what you would need to do.
Set your step to 1 second, update as often as your program allows, 
and then have a consolidation for 60 second periods. You would then 
get 1 minute reporting periods, each with a min/max/average for the 
60 x 1s step times it contains.

See Alex's tutorials here :
particularly the one on normalisation and consolidation

Simon Hobson

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