Calculated/Derived values/data sources

[naterg]

Hi all,

So I'm working on monitoring templates for Tomcat7. I have several data sources like memory total+used stats that I'm graphing but I'd also like to graph derived values like memory free (total-used) or nonHeap free (adding multiple values). I've done that with CDEFs in my graph template but ran into issues with multiple graphs using the same template somehow having a different data element order which breaks the CDEF.

Am I doing something wrong? Is there a way to re-order the data elements in the RRDTool command per graph? (that seems like a lot of work too) Is there a better way to do this?

I noticed some discussion about the COMPUTE data source type in rrdtool. I noticed its available in Cacti 1.1 but I haven't been able to find any notes/docs about how to use it in Cacti...

I'd appreciate any pointers

UPDATE: unlinking, saving and re-linking one of the graph items to its data source in the graphs with the incorrect order issue seems to have fixed the order problem for now