[rrd-users] Re: Calculating traffic

[Alex van den Bogaerdt]

Serge Maandag wrote:

> Your step is 60 and your heartbeat is 600. Your hires RRA has a xff of
> 0.5.
> 
> So your graph will have a resolution of 1 value per 10 minutes tops
> (600).

This is something you can't say.

>   rrdtool create port_xxx.rdd --step 60 \
>   DS:in:COUNTER:600:U:U                 \
>   DS:out:COUNTER:600:U:U                \
>   RRA:AVERAGE:0.5:1:600                 \
>   RRA:AVERAGE:0.5:6:700                 \
>   RRA:AVERAGE:0.5:24:775                \
>   RRA:AVERAGE:0.5:288:3725              \

What this means is:

Each PDP is worth 60 seconds (--step).

Updates cannot be further apart than 600 seconds (600 in DS).

If updates occur, say, every 300 seconds then with each update there
will be 5 PDPs calculated.

The rate calculated for each of these PDPs is then checked against
the minimum (U == unknown) and maximum (also U) values.  When the
rate is allowed, it will be used to compute the value for a CDP.

CDP calculation:
0.5 times the amount of PDPs needed per CDP may be unknown.  The RRAs
need 1,6,24 and 288 PDPs per CDP.  The RRA stores 600,700,775,3725 of
these CDPs.

Total time per RRA:
The total time per RRA is the time per PDP (your --step time) multiplied
with the amount of PDPs per CDP (steps) multiplied by the amount of CDPs.
The numbers are:
60*1*600 == 36000 seconds == 10 hours
60*6*700 == 252000 seconds == 70 hours = 2 days 22 hours
60*24*775 == 1116000 seconds == 12 days 22 hours
60*288*3725 == 64368000 seconds == 745 days

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