[rrd-users] Re: Cricket/RRD fetch resolution problem (2nd try)

[Alex van den Bogaerdt]

Scott C. Kennedy wrote:
> 
> I've run some queries based on modifying the start & end times to
> be not in a "2 hour moment", but...

>      + rrdtool fetch data2.rrd AVERAGE -e 996782400 -s end-31days
>      + wc -l
>           375

This one is on a 2-hour boundary:
    [alex at home /tmp]$ perl -e 'use POSIX;print ctime(996782400);'
    Thu Aug  2 22:00:00 2001
(this is UTC time + two hours, so 20:00:00 UTC)

OTOH:
>      + rrdtool fetch data2.rrd AVERAGE -e 996782700 -s end-31days
>      + wc -l
>           376
This isn't, as it's clearly 5 minutes (300 seconds) after the previous time.

So, the problem is different.

> It seems that every query on data1.rrd returns the large number of values, yet every
> query on
> data2.rrd returns the 2 hr average values.

Alright, check the properties of data2.rrd using "rrdtool info".  Maybe
this RRA is missing:
     # one point per 5 minutes, spanning 366 days
     rra             5minUse     AVERAGE:0.5:1:105500
Make sure to check both the number of rows *and* the consolidation function!

> Maybe, I should look at this a different way, is there a way to specify with RRA to
> fetch from?

ahum:

> Alex van den Bogaerdt wrote:

> > Oh, and if everything is working as it should you can use the resolution
> > flag to rrdtool fetch.   *If* the time is an exact multiple of 2 hours,
> > you can choose which RRA to use.  However, if you try to select the
> > 2-hour RRA but fail to query correct start and end times, it fails:
> > "--start 00:00 --end 22:00" will work (assuming a timezone that is an
> > even number of hours away from UTC) but "--start 00:05 --end 22:05" will
> > not work.  It will return data from the 5-minute RRA.

HTH
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