Virtualization on Debian

[Robert Brockway]

On Sat, 10 Feb 2007, Meng Cheah wrote:

> Are virtual servers common in production systems now?

Yeah they are.  This has some up on various Sysadmin lists like SAGE & 
SAGe-AU too.

> More to the point, what is your experience?

I use a lot of virtualised boxes in production now.  Less power 
consumption, less physical space needed, less heat generated, less 
hardware problems and a high degree of flexibility including the ability 
to reconfigure the virutal boxes without picking up a screw driver.  If 
the host server dies transferring the virtual boxes to another box is 
easy.

> What to look at first (Xen or other options) using a Debian system?

I use Qemu with the kqemu kernel module.  http://www.qemu.org

> Any gotchas to look out for?

Virtualisation costs a little in terms of performance.  Even if you can 
pass through the instructions in an efficient manner there is still the 
overhead of two filesystem layers to consider.  Thus it is not a good 
choice in high performance computing (although people are doing it).

Virtualisation lets you move towards "one function per box"[1] which 
greatly simplifies system/network management without having to have dozens 
of boxes taking up space & sucking power.

I regularly setup virtual boxes for the following uses:

Production Web servers
Reverse Proxy Servers (ie, Apache as a reverse proxy)
Development/Web Development servers
DB servers
Extra DNS servers (I like to have 2 real DNS servers)
Mail servers
General shell access servers
Thin Client hosting environments

Demand is almost always low enough to justify a virtual box over a real 
box.

[1] Sometimes one function can be replaced with "group of closely related 
functions" without violating the principal behind this idea.

Cheers,

Rob

-- 
Robert Brockway B.Sc.        Phone:          +1-905-821-2327
Senior Technical Consultant  Urgent Support: +1-416-669-3073
OpenTrend Solutions Ltd      Email:          support-wgAaPJgzrDxH4x6Dk/4f9A at public.gmane.org
                              Web:            www.opentrend.net
Contributing Member of Software in the Public Interest
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists