[rrd-users] Re: create rrd files - basic questions

[Serge Maandag]

-In the DS configuration option, if I´m going do graph bits traffic, the 
´min´and ´max I put in bits (example: 10000000 for 10Mbps)?

The snmp poll gives back bytes, which you store as counter. If you expect the maximum to be 10 Mbit/s, than that is the same as 125 kByte/s. your max would be 125000.

-In the configuration option RRA, I did not understant how to use the CF 
option and when?

If you have defined a DS, the rrd still is not storing anything. Storing of data points is done in RRA's. You will have to define 1 or more RRA's. Follow the tutorial on the site to have it explained in detail. An example is: RRA:AVERAGE:0.5:1200:1
That would create 1200 rows of memory (PDP's) which contain the average value over the time of 1 step. So this RRA will hold  1200 * 5 min = 100 hours of data, about 4 days.

- For the xff option, I did not understant what really is this factor 
(may you can give an example) and what is the factor I need to use.

If you set it to 0.5, then half the updates done in the time that is covered by 1 row in the RRA (above: 5 min's) are allowed to have failed. It will calculate the value for the PDP from the succeeded updates. If more then half of the updates have failed, the entire PDP is considered Unknown.

-The manual (rrdtool create) do not explain what is primary data point 
(PDP), and this option became not clear for me.  What doc explain what 
is PDP?

A PDP is one row of data in a RRA. You really should understand what a RRA is, please do the tutorial.

-Assuming the I´m collecting some data every 300 seconds. If I want to 
store for 24 hours, I hato put as value for the option rows a number 
that multiplied for 300 seconds give me 24 hours in seconds? In the 
manual, the example put 1200 * 300 = 1000hours.  THe number 1200 is the 
number that I cited above?

(1200 PDP's * 300 Secs/PDP) / 3600secs/hour = 100 hours :)

To store 24 hours, you'd store (24*3600) / 300 = 288 points -> make it 300 or you're graph may get low-res (a different story).

- Thank you.

No thanks.


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