On Sun, 14 Aug 2005, Ken Fuchs wrote:

> I still think a cluster is what you need.  There are several Linux 
> cluster distributions that are available on Live CDs that are easy to 
> setup.  They should also have hard drive install options.

[snip]

> How well a cluster will work depends on how fast the interconnect is and 
> how much information must flow between nodes?  These same issues will be 
> need to be addressed in a single system with several multi-core CPUs, 
> although the interconnect is bound to be much faster in a single 
> (non-cluster) system.

Why do I need a cluster?  I don't fully understand how clusters can work 
for me, but I am very interested.  In fact, I have been thinking that I 
would expand the system in the future to include other machines in a 
cluster configuration, but right now I think one might be enough.  If I 
have a single machine with multiple sockets/cores, the OS will 
transparently handle the multiple jobs and level the load across the 
cores.  So the single-machine-multiple-core setup is easy to work with. 
I'm not as confident about the cluster setup.

In case someone on this list has some experience or knowledge in this 
area, here are some questions:

(1) How are jobs handled in a Linux cluster?  Obviously, someone logs into 
one machine and jobs are sent to that machine or to other machines, but 
how does the system decide where to send a job?  To submit a job, does the 
user have to specify any parameters to determine where/how it will run?

(2) If different nodes in the cluster have different amounts of RAM 
available, how does the system decide where the more memory-intensive jobs 
will run?  If it does this automatically, ignoring memory requirements, is 
it possible to request that a certain job go to a certain node?

In general, I need to understand job control in the cluster system to 
understand how that system can be used for the kind of work I do.

Thanks!

Mike