[rrd-users] Re: Filling in NaN's?

Clifton Royston cliftonr at lava.net
Fri Apr 27 02:27:34 MEST 2001

On Thu, Apr 26, 2001 at 08:16:19PM -0400, Adam Rothschild wrote:
> On Thu, Apr 26, 2001 at 03:43:37PM -0700, Mark Smith wrote:
> > Are you looking to do this after the fact or in real time?
> After the fact.
> And yes, I realize the downsides to this, but for the given
> application, flawed data is better than no data at all. :-)

  However, I hope you realize what you are getting via your proposal is
*not* flawed data, it's no data at all - you're only making it look as
though you had data.  In some sense, it's "negative" data - you are
removing the data indicating that you were unable to collect data
values at a certain time, which could be useful data in itself.  As you
can tell, I'm philosophically opposed to this.

  If you only want smooth looking *graphs*, there's probably a way to
do this with some of the CDEF expressions in the grapher, using the
"PREV" command.  E.g. assuming orig is the def for your original data
source, something like:


should give you a graph with flat-lines where the data is unknown, much
like MRTG's old behavior.

  -- Clifton

 Clifton Royston  --  LavaNet Systems Architect --  cliftonr at lava.net
   WWJD?   "JWRTFM!" - Scott Dorsey (kludge)   "JWG" - Eddie Aikau

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