Custom graphs with multiple data sources

[Alan Sparks <asparks (at) doublesparks.net>]

I am monitoring a set of load balancers (Alteons) which each have at 
least 1, but possibly/usually more, virtual addresses configured (for 
server load balancing groups).  At the moment, I use a custom script to 
poll each device via SNMP and send a single status message per device to 
Hobbit, based on the session loads on those "virts."  I am using NCV for 
graphing.

However, with this, I am only able to manage one graph, and one data 
source, per device.  I would like to graph all the session values.
I would also like to use multiple RRD files.  My experience with the 
single-file, multiple-DS approach is that, if I add another virtual, 
graphing will break (updates error out, probably since the RRD was not 
created with this new data source defined).

I am amenable to changing the scripts to use the data channel approach 
(using the --extra-script method).  I am hoping that I could use the 
hobbitgraph RRDFN/RRDIDX/RRDPARAM keywords to create the graphs.  But, 
the documentation for custom graphing implies that only a single 
filename for the incoming data can be specified, so I see no way to 
split the data into multiple files, single DS per RRD.

Short of creating a separate test column for each virtual I am 
monitoring, is there a better way to collect/plot this information?
Thanks in advance for any suggestions.
-Alan

--
Alan Sparks, UNIX/Linux Systems Integration and Administration
<asparks (at) doublesparks.net>