"One great thing about Linux is its rock-solid nature even when
you load it up with as many daemons and services as you like. Yet,
often 'best practice' dictates you separate out some apps across a
couple of servers or at the very least provide a safe development
environment which is distinct from your production environment.
"Or you might be about to make a serious change in your
environment and need a safe way of making a complete backup with
instantaneous restore if need be..."