[rrd-users] Re: Data differ from RRA to RRA - normal?

Heiko Teichmann inno.vation at gmx.net
Thu Oct 12 15:03:05 MEST 2006

Alex van den Bogaerdt wrote:
> Unknown data can play a role here.  If you have an xff setting other
> than 0, weird things happen (hence "X-Files Factor" ...)
I have proofed that - and it seems to be so! That could be the reason 
for different results - in fact the data I investigated were from a day 
with a couple of unknow data in the 300 and 1800 rra.

>>I though it could not differ, because the small resolution (300)
>>database feed the larger one (1800) and so on ?
> This is not true.
> Each time an interval is computed, it is fed to every RRA.  When an
> RRA has enough data to generate a new row, it will do so.
Did that mean that even the RRA with the large pdp_per_row (288) stores 
the data for the 288 steps and computes then the new row for the RRA? If 
so what would be the divisor for the average computing if some data 
failing (e.g. 2 steps fails -> 286 data points available all with the 
same value; Question: average = (286*x)/288 or (286*x)/286 )?

> The RRA containing 300 seconds per row, will generate a new row each
> time new data is coming in.  The RRA containing 86400 seconds per row
> needs 288 intervals to generate one row.
> Data is not moved/copied from one rra to another.
Ok, make sense.

Thank You so far


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