[ILUG] Virtual server question

[Thomas Pedoussaut]

Kevin Philp wrote:
> We are looking into options for putting together our next server. We
> are a small company with a small network and have used a single
> machine to act as general server for everything - not ideal but you
> have to start somewhere. I have been reading about running multiple
> virtual servers on one machine and want to check if my understanding
> is correct.
>
> Does it make sense to run virtual servers using the same topology
> logic as you would with physical servers i.e. a server for the
> firewall and another server for the internal network. Does it make
> sense to split off various functions into different i.e. a separate
> server for the local NFS server and another for external SSH access.

Firewall is the tricky one, as obviously you'd prefer a physically
separate box.
NFS is another one where you want as much raw power as possible.

Mostly virtual servers would be for either privilege separation (like
running independent boxes for different clients, or running software
that require to be root and can't have multiple one), or for trying to
mimic production environment in dev or test without buying as many servers.
Another example is when it's difficult to have multiple versions of a
software installed at the same time, think php4/php5.
A last example is ready-made appliance, where you have self installed CD
with very tweaked configuration of various servers, like various
Asterisk appliance.

Among the drawbacks of virtualisation is the repetitive usage of RAM for
the OS itself. If you want your LAMT stack split onto Apache / Tomcat /
Myslql servers, you'll have to load 3 OSes.

And don't forget that even they are running on ONE harware, it's still
independent machines that all needs patching/monitoring ...

-- 
Thomas