[ Thanks to Douglas Eadline for this
link. ]
“It is a common practice to have development and test servers
for each production server, so that you can experiment with changes
without the fear of breaking anything important, but this is
usually not feasible with clusters. So how do you try that new
version of your favorite program before committing it to the
production cluster? A cheap and convenient possibility is to build
a virtual cluster.“Thanks to the Xen virtual machine monitor, you can create a
number of virtual machines, all running simultaneously in your
computer, install different operating systems in them, or just
different configurations, and connect them via (virtual) network
cards. Xen is a terrific tool for building virtual Beowulf
clusters. It can prove useful when learning or teaching about
clusters or for testing new features/software without the fear of
causing major damage to an existing cluster…”