Re: [rrd-users] Aggregation functions for combining whole data sets

On Sun, Mar 23, 2008 at 12:44:21PM +0100, Carsten Aulbert wrote:

[snip: one DS out of each of 24 databases]
>
> CDEF:preavg=watin001,watin002,watin003,watin004,wa tin005,watin006,watin007,watin008,watin009,watin01 0,watin011,watin012,watin013,watin014,watin015,wat in016,watin017,watin018,watin019,watin020,watin021 ,watin022,watin023,watin024,+,+,+,+,+,+,+,+,+,+,+, +,+,+,+,+,+,+,+,+,+,+,+
> \
> CDEF:avg=preavg,24,/ \
> "LINE1:avg#FF0000"
>
> Is there a better way to do it?

You can combine those two CDEFs:

CDEF:avg=watin001,watin002...watin024,+,+,...+,24,/

Be aware of the following: should one (or more) of these DSes become
unknown, the sum will be unknown.

For this reason, AVG exists: CDEF:x=a,b,c,d,4,AVG

One possible problem though: if only one out of 24 is known, that will
become the 'average'.

HTH
--
Alex van den Bogaerdt
http://www.vandenbogaerdt.nl/rrdtool/

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