[Beowulf] Need advice on cluster hardware

[Craig Tierney]

On Thu, 2005-01-20 at 13:20, Steve Zapytowski wrote:
> I wish to know if all machines in a Beowulf Cluster must be
> identical.  Can you please answer this question for me?
> 

Short answer: no.
Longer answer: no, but it may be much harder to program efficiently
               depending on your application.

If you want to build a Beowulf cluster with nodes of different
speeds (or architectures) it will more difficult to break the 
problem up so that you are maximizing cpu usage across all nodes.

If you have a program that does a lot of repetitive steps and
the size of each piece is very small compared to the overall 
program and there isn't a lot of interprocess (inter-node) communication
then you can use a heterogeneous cluster
quite efficiently.  Programs that are written as master/slaves
may take advantage of this type of system (eg. ray-tracing and 
some geophysics applications).

If you are running programs that have dependencies between the
nodes, like inter-node communication, it can be more difficult
to make the model run efficiently.  Weather models (MM5, WRF) 
could work, but will run as slow as the slowest node.  If you
are writing your own software you can treat the problem similar
to if you are addressing load balancing issues to better use
the different systems in the cluster.

Craig