[rrd-users] Re: RRD general info about length of storage

Clay Jones clay at clay-jones.com
Wed Feb 13 15:26:01 MET 2002


What you say below seems to conflict with what Tobias said in his response:


"the RRAs are independent, data for each RRA comes direct from
the data you enter ... each RRA has its own 'holdingarea' where
data is prepared to enter the RRA"

I'm interpreting "the data you enter" to be the RRD.

Let's say I set up a database to collect every five minutes.  I want to see
weekly, monthly, and yearly average.  Would the RRD contain 1 week's worth
of data all the time (except initially)?  How would the monthly graph be
generated?  4 weeks of RRA data?  4 1/2 weeks?  Would the yearly graph
simply be the points from 52 weeks of consolidated weekly RRA data?  Or
would it be 12 points from 12 monthly-consolidated RRA data?

I believe this question speaks directly to the algorithm of RRD/RRA storage,
and it will impact the implementation we choose.


On 2/12/02 8:21 PM, "Alex van den Bogaerdt" <alex at slot.hollandcasino.nl>

> Clay Jones wrote:
>> Is it correct that the RRD would contain 1 year's worth of data points if I
>> specify an RRA with a yearly average?  Is keeping 1 year's work of 5 minute
>> data points the only way to generate a yearly average graph?
> No.
> It works like this:
> - The database is working on intervals of "x" seconds.  The default is 300.
> - Each RRA works on a certain amount of intervals per slot
> - Each RRA has a certain amount of slots
> Suppose the database works with intervals of 300 seconds, the RRA works
> with slots of 12 intervals, this would mean that each slot is worth
> 3600 (12*300) seconds of data (this is an hour).  If you store enough
> of those slots (366*24), you can display one year of data.
> You could also work with an RRA of 288 intervals.  This stores 86400
> seconds per slot (one day) and you'd need 366 of such intervals.

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