[Tfug] virtualization

[Matt Jacob]

I'm only familiar with VMware products, and only on Windows at that, but 
I've found virtualization to be very cool and very practical. It's great 
for development for a lot of reasons, some of which include:

* My dev boxes are on my laptop, so I can work even when I'm out of the 
office and without an internet connection

* I can share VM images with co-workers, so getting someone configured 
for a dev environment is really, really easy

* I can try new things without fear of causing irreparable damage 
(simply by cloning the image or taking a snapshot beforehand)

* It's easy to play with things that would be impractical to configure 
on actual hardware just for testing purposes (e.g., a cluster of 
load-balanced web servers)

* I can test out new distros and releases before upgrading the 
production servers, which adds a huge layer of CYA

And I'm sure there are other benefits, too, but those are the main ones 
that stick out to me. If you have any experience with VMware, I'd be 
interested to know how it stacks up to Xen.

My only experience in using Xen is that my web server is a Xen-powered 
virtual machine from the good folks at SliceHost. In that context, Xen 
has been flawless. It seems like there's really good resource isolation, 
which may not always be the case with VMware. Networking on a Windows 
host is really easy to configure with VMware, though.

Matt

Robert Hunter wrote:
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> After a month or so of fooling around with xen, I thought I'd share
> some experiences, and ask others here about their's.
> 
> I have successfully used xen on a dual-quad server at work, using
> Debian as both host and guest OSes.  It is quite easy to setup,
> although the networking is a bit tricky.  Not only do you need a
> working knowledge of iptables, but depending on your requirements, you
> may also need to understand how Linux bridging (ebtables) works, as
> well.  There is good information at the xen networking wiki, and also
> the ebtables project has a detailed document with nice diagrams on
> Linux bridging and how it interacts with Linux routing.  My networking
> requirement consists of domUs sharing one or more network interfaces,
> where certain ports are forwarded to specific domUs.  In this case,
> bridging is not necessary, and I use a NAT configuration.  However, I
> may decide someday to provide routing services on a domU itself, in
> which case bridging will come back into the picture.  This ability to
> create a virtual network on a single box with multiple guest OSes is a
> godsend for both application hosting, as well as software development
> purposes.  The only sticking point is that you need multiple
> processors and boatloads of memory if you want things to run smoothly.
> 
> The story changes somewhat as I continued testing xen on my laptop.
> My T61 comes with a dual core processor, and enough memory to run at
> few domUs.  My plan was to run a WinXP guest OS so that I could use
> a few apps that won't run under wine.  After a bit of work, I managed
> to get an XP install running smoothly, however, I had to disable
> Intel's 965M X driver, because it consistently crashed my machine.
> Furthermore, I was unable to get network working.  I spent the better
> part of a day googling and trying various things, to no avail.  I
> would interested in any stories of success of running an XP domU.  If
> and when I figure this out, I'll report back.  In the meantime, I'm
> running virtualbox, and my Windows-only interactive Korean
> instruction software (which uses both audio playback and recording) works
> like a champ.  The one unfortunate thing is that virtualbox is very
> CPU intensive, but at least I can "pause" the guest when I'm not using
> it.
> 
> Any stories, anecdotes, and advice about virtualization experiences
> would be most welcome.
> 
> - --Rob
> 
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