"In theory, you can use any old PC. The minimum requirement is
that it must be able to run Linux; so that narrows the choice down
to almost any PC from the last 10 years. But in reality, the
cluster works best if the machines that you're linking together are
relatively close in specification, especially when you start to
take running costs into consideration. A 1GHz Athlon machine, for
example, could cost you over £50 a year in electricity costs.
You'd be much better off spending this money on a processor upgrade
for a more efficient machine. A similar platform for each computer
also makes configuration considerably easier.
"For our cluster, we used four identical powerful machines. You
only need powerful machines if you're making a living from
something computer-based -- 3D animation, for instance -- where you
can weigh the extra cost against increased performance. We're also
going to assume that you have a main machine you can use as the
master. This will be the eyes and ears of the cluster, and it's
from here that you'll be able to set up jobs and control the other
machines."
