[hobbit] ganglia-style graph aggregation with hobbit

[Henrik Stoerner]

On Wed, Sep 20, 2006 at 04:51:25PM +0100, Gildas Le Nadan wrote:

> I'd like to completely replace the ganglia system we have here with hobbit.
> 
> Most of the needed features are there, except the ability to produce 
> aggregated graphs with multiple hosts, as in 
> http://monitor.millennium.berkeley.edu/?c=PSI%20Cluster&m=&r=hour&s=descending&hc=4

I think it can be done just by putting together the right graph
definitions. RRDtool which is used to generate the graphs has all
of the necessary functions to build such aggregate graphs, and 
Hobbit already stores all of the information you're tracking. So
it should "just" be a case of putting together the right input for
the RRD graph module.

I have done it on an ad-hoc basis by hand-coding some extra graph
definitions in the hobbitgraph.cfg file, but this is not suitable
for the case where you have lots of hosts - for that you need something
a bit more flexible that lets you select a group of hosts, and generate
a graph with the type of aggregation you want.

> What would be the best way to do it? I'd like not to reinvent the wheel, 
> so if some bits are already existing, I'd better use them...

Check the hobbit_hostgraph.cgi module in Hobbit 4.2, and the "multi"
definitions in hobbitgraph.cfg. The current hobbitgraph tool lets you
generate a graph for multiple hosts, but just overlaid on top of each
other. I think it might be possible to just modify the "multi"
definitions in hobbitgraph.cfg to produce an aggregate graph also.


Regards,
Henrik