[rrd-developers] How to create a new Data Type and Consolidation Function?

Long V long_at_work at yahoo.ca
Tue Apr 12 17:13:37 CEST 2011

----- Original Message ----
> From: Reinhard Scheck <Reinhard.Scheck at team-scheck.de>
> To: rrd-developers at lists.oetiker.ch
> Sent: Mon, April 11, 2011 11:32:16 AM
> Subject: Re: [rrd-developers] How to create a new Data Type and Consolidation 
> On 11.04.2011 09:32, Tobias Oetiker wrote:
> > Hi Long,
> >
> >  Friday Long V wrote:
> >
> >> Hi Tobi,
> >>
> >> As I  explained earlier in this same thread, I needed a solution for Cacti 
>to  be
> >> able to sum up the difference between 2 counter  readings.
> >
> > seems a bit extreem to hack something so alien into  rrdtool instead
> > of fixing cacti, but there you go ...
> I do support  Tobi's request.
> And I do not see the need of introducing an rrdtool  hack.
> Perhaps I missed sth here, but IMHO, we can achieve this with cacti.  This 
> be discussed in the Cacti forums.

Hi Tobi, Reinhard,

RRDTool and Cacti has changed my ways at looking at system monitoring and 
reporting. I only had logs to mine before.

My intention was not to do an extreme hack but to add a useful functionality. I 
truly believe my use case "keeping a count as a count and not a rate and have 
SUM consolidation for different RRA" is a useful feature.

If I just need a hack, I wouldn't go all the trouble of looking for a 
certification test-suite so that I can submit my feature to RRDTool source to 
have it available for everyone else that require the same functionality as me.

Way back, I have asked on Cacti forum how to do this at Cacti level "How to 
display COUNTER (not per second but totaling diff) ?" 
<http://forums.cacti.net/viewtopic.php?f=21&t=41635> but didn't receive any 

So I thought this feature was not appropriate at Cacti level but more at RRDTool 
level (for low level implementation to benefit a wider audience).

My intention is still the same, I absolutely need to implement this feature and 
I want to do it the right way so my effort can benefit the community not just me 
(my way of saying thanks to useful projects is to give my time and speak about 
it to my colleagues).

You guys are the developers. You clearly know better than me how to get things 
done the proper way so I am willing to listen to your advice on how to implement 
this feature.

Please let me know ASAP because I have already spent quite some time 
implementing this feature at RRDTool level and wrote a regression test tool that 
I currently don't have much time left to change things around.

Just for fun, attached is my working RRDTool patch that adds DST_DIFFERENCE and 

Hope to hear from you soon.

> Reinhard
> aka  "gandalf"
> Cacti  Developer
> _______________________________________________
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> rrd-developers at lists.oetiker.ch
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