[Orca-users] Re: Orca date collections

[Blair Zajac]

Steven Olson wrote:
> 
> We're trying to average the number of NaN's per total # entries
> for system uptimes to determine overall up/downtime percentages
> but need consistent increments for the entire periods we're
> trying to graph.

OK.

> 
> When fetching data from the 1 minute runq rrd files, using a start
> date of end-1day, the timestamps are every 5 minutes.  Start date
> of end-1month, timestamps are now every half hour; start date of
> end-1year, timestamps are once a day.  All per FAQ.
> 
> My newbie questions are:  does the "once every 5 minute" data still
> exist in the rrd going back to epoch,

No, it is lost after a certain period of time.  In Orca's case,
look at lib/Orca/Constants.pm to see how long the data exists.  Here
RRA is a Round Robin Archive and there can be 1 or more in a single
RRD file:

# The first RRA is every 5 minutes for 200 hours, the second is every
# 30 minutes for 31 days, the third is every 2 hours for 100 days, and
# the last is every day for 3 years.

So you get the 5 minute data for 200 hours (almost 8 days).

> and if so, how does one
> extract it using fetch?  If not, are the rrd's getting regenerated
> once per day to change the number of datapoints?  Any help, thanks.

The size of the RRD file is constant.  When data gets old enough, it just
falls off the end of the particular RRA in the RRD file.

Best,
Blair

-- 
Blair Zajac <blair at orcaware.com>
Web and OS performance plots - http://www.orcaware.com/orca/