[rrd-users] Data Source Name - 19 character limitation

Simon Hobson linux at thehobsons.co.uk
Wed Nov 21 12:06:16 CET 2007

Clint Cronwright - Jacarta wrote:

>What the problem is that for trending purposes, Midguard uses the RRD OID
>number and the Element Name (DS Name) from the MIBs in order for it to work.
>When I create our Jchecks, I upload them to the client's Midguard system and
>using the RRD function, the RRDDaemon updates the data in its database and
>also creates a rrd file (which has data points in them) which RRDTool uses
>to draw and plots the charts.


>Therefore, we concluded and looking through the internet that RRDTool has a
>19 characters element name restriction (from
>http://forums.cacti.net/post-385.html). Any more characters than 19 in the
>element name, the error counter goes up.

So the problem is the other tool, not rrd. It's ignoring any possible 
constraints in DS names.

You need to complain to the Midguard vendor that their tool is 
broken. They may well argue that it's an rrd problem for having a 
short limit on name lengths, but that's no excuse - there is going to 
be SOME limit even if it were increased, and they should be honouring 
that limit.

BTW - is the limit documented anywhere ? If not then it might be 
worth doing so to avoid (or at least minimise) such problems in the 

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