[rrd-users] Re: Having problems with rrd graphs... help please

[Alex van den Bogaerdt]

On Mon, May 10, 2004 at 09:45:26AM +0200, Fernando Nieto wrote:

> Then if I receive the values 1,3,1,5,1 for one DS at t0, t1, t2, t3... my
> rrd will store exactly those values:
> 
>              AVERAGE RRA  	MAX RRA
> 	10:00  	1		  1
> 	10:05  	3		  3
> 	10:10  	1		  1
> 	10:15  	5		  5
> 	10:20  	1 		  1
> 
> and these are also the values I get when I use rrdtool fetch. With steps=1,
> the RRA will store exactly the same values even if I use AVERAGE, MAX, MIN
> or LAST.

Indeed.


> When I graph these data I think I should see the same info as when I fetch
> it, even if my graph is 400x100 or 600x200. 

Nope.

If one pixel describes the time between 10:00 and 10:15, the values used are:

   3  (10:00 to 10:05)
   1  (10:05 to 10:10)
   5  (10:10 to 10:15)

If you display the minimum, 1 will be selected.
If you display the average, 3 will be computed.
If you display the maximum, 5 will be selected.
If you display the last,    5 will be selected.

If one pixel describes the time between 10:00 and 10:10, the values used are:

   3  (10:00 to 10:05)
   1  (10:00 to 10:10)

If you display the minimum, 1 will be selected.
If you display the average, 2 will be computed.
If you display the maximum, 3 will be selected.
If you display the last,    1 will be selected.

Different results, because of a different time span.

If this still does not makes sense, I cannot explain it to you.

Alex

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