[rrd-users] Re: Specification of RRA Boundaries

Alex van den Bogaerdt alex at ergens.op.het.net
Tue Sep 14 11:10:38 MEST 2004

On Tue, Sep 14, 2004 at 06:23:10PM +1000, Richard Nelson wrote:

> >   DEF:h00=....
> >   CDEF:h01=h00,PREV
> >   CDEF:h02=h01,PREV
> >   CDEF:h03=h02,PREV
> >   CDEF:h04=h03,PREV
> >   [...]
> >   CDEF:h23=h22,PREV
> >   CDEF:maxval=h00,h01,h02,h03....  MAX,MAX,MAX...
> >   AREA:maxval
> >
> This, sadly, will not give me what I want (assuming you meant
> CDEF:h01=PREV(h00) ).

I wrote PREV and I ment PREV.  But PREV(x) seems to do the same trick.

Suppose the maximum occured between 23:00 and midnight, then I
don't think you can _draw_ this maximum between 00:00 and 01:00
before.  RRDtool has no knowledge about the future.  You can
GPRINT the maximum when you create a graph from 00:00 to 24:00.

If you use rrdtool graph without graphing functions, you can
PRINT (without the G) the maximum.  Feed it to another database
with step==3600, steps==1, heartbeat>=86400 and timestamp midnight.
RRDtool will use this single update to fill 24 PDPs.  They will
all be the same, I guess that's what you're after.

It that is it, there's no need to use the CDEFs described above.
Just query your original database, find the maximum, update the
other database and use that to plot the maximum.

You want an answer?  You'd better follow the following guidelines!
Linesize well below 80 chars. Reply to the list, not to me. Trim
irrelevant lines. Answer below the remaining paragraph.

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