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As part of our discussion on advanced system management topics, let's talk a little bit about Xen virtualization. Now, virtualization is kind of a newer technology as far as openSUSE and Linux goes. It's been around for a little while in other operating system, but we're just now getting a really good product out there for virtualization and some of you may be wondering, well, what is virtualization and what can it do for me? Virtualization basically gives you the ability to run multiple operating systems and virtual machines or computers under a single installation of openSUSE. Now, why you might be thinking about that little bit in your mind and saying well, what does that mean? Essentially it allows you to run a computer inside of a computer. You can have an openSUSE installation and you can virtual machines that run Windows and Linux under openSUSE. So you could open up a Windows virtual machine and use Microsoft Office and other Windows products, or you can open up other Linux machines under openSUSE such Red Hat or UBUNTU and use them for whatever you need, such as an email server or a DHCP server and so forth. Essentially you could run multiple system all under the guise of one big operating system, openSUSE. Now, virtual machines also allow you to run separate systems that may run different software or have different functions, but they also may have other hardware resources. What happens is openSUSE, through its virtualization product, Xen, will share its host resources such as disk space and memory and kind of virtualize other hardware devices such as sound cards and so forth and the virtual machines that are running will think that hardware is basically native to them, such as a Windows device, for example. They won't know the difference. All these virtual machines think that they're separate computers physically on a box. Now, virtual machines can interact with each other and with their host on several levels; on a network level, file level and so forth. You can share files among them, they can talk to each other over the network, just as if they are separate machines and really they are full-fledged machines. They're just virtual machines. That's all. Now, the virtualization product that comes with openSUSE is called Xen and it can be installed in openSUSE. It's not installed by default, but it can be installed. It does come with some of the media and Xen can be used on other distros as well, so you can run Xen under another Linux distribution. But it is a Linux product. Now, there are other products out there that are free that you can use as well. Microsoft Virtual PC, which really is only useful if you're running it on Windows, but there's also VMware server out there and the other VMware products that can be run on Linux or Windows. And they're comparable to Xen. And in some ways, they may even have more functionality. Xen is getting to the point where it's almost as mature as those products, but it's still a great product, it's free and it's built-in. Now, Xen can be installed on openSUSE during the installation or after the fact and that's something you need to really plan on. If you're going to run Xen on your machine, then your machine really doesn't need to do much of anything else. And the reason is is virtual machines can take up a lot of hardware resources; memory, hard disk space and so forth. So if you're going to use Xen on your openSUSE box, I would probably dedicate that box to Xen. And that's not really a big deal because you can still use other things, such as Office products and things like that, but use them in your virtual machine. You might have a virtual machine that you simply surf the Internet from or that you compose documents from. You also may have a virtual machine that serves as proxy server or a DNS server for a network. There's so many things you can do with the virtualization technology that comes included with openSUSE. Now, there's to mode that Xen primarily uses; full virtual and para-virtual modes. Full virtual is what it requires to run Microsoft Windows products and para-virtual modes run Linux operating system. The one thing about Xen is it uses several different packages that are going to have to be installed, so sometimes it can be a little bit problematic to install and get to running right because you may have to download different packages and different versions of the packages. So sometimes it can be a little bit of a pain to get started and going. Once it does, it's a great product. While we're not going to go in-depth and show you a demonstration of Xen here, I wanted to just give you enough information to know that it exists and a little bit about how it works. I would highly recommend if you're interested in it, go and look at the openSUSE 10.3 reference guide for more detailed information on setup and use of Xen. Also, there are some good Xen virtualization resources out there, both on the Novell site and other Linux sites.