[rrd-users] Finding the order of DS names in an RRD (blind updates).

Stanley Hopcroft Stanley.Hopcroft at IPAustralia.Gov.AU
Mon Aug 25 10:36:45 MEST 2003

Dear Ladies and Gentlemen,

I am writing to ask how a Perl program can determine the order of the DS 
names from an RRD (to update it without hardcoding an update template 
or a DS sequence), if this is possible ?

I think this is relevant to the case where an application wishes to

 . update only one RRD (with a whole bunch of measurements)

 . reserve DS and RRAs in the RRD for future use (with generic
names);some of the generic names will eventually be 'tuned into'
production names and will be updated.

 . at run time determine the update template by asking (somehow) the RRD 
   for the DS names and sequence.

my @stuff = `rrdtoo info` provides this information but at the cost of a
fork (and handling the possibility that fork() fails);  RRDs::info
provides the DS names but in hash key order, which usually differs from
that of `rrdtool info`.

Are there any other alternatives ?

This is beginning to sound like a bad idea or vica versa, an argument 
for one RRD per logical measurement.

RRDtool is simply a fantastic product, one that seems to find new 
applications for itself all the time - in this case, a giant single RRD 
(having one RRD makes enquiries easier), holding printer page counts.

I sincerely hope that the author gets _all_ the DVDs he asks for and 
that they are a suitable and satisfying reward for something I am very 

Thank you,

Yours sincerely.

Stanley Hopcroft

'...No man is an island, entire of itself; every man is a piece of the
continent, a part of the main. If a clod be washed away by the sea,
Europe is the less, as well as if a promontory were, as well as if a
manor of thy friend's or of thine own were. Any man's death diminishes
me, because I am involved in mankind; and therefore never send to know
for whom the bell tolls; it tolls for thee...'

from Meditation 17, J Donne.

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