Editor's Note: If you're just joining this series, also see part one: What Xen is, how Xen works and how it compares.
After choosing Xen as your preferred data center virtualization solution, you have to decide what type of Xen to run. Generically speaking, there are three brands of Xen that offer the support and stability that is required in a modern data center. There is the XenSource solution, the Xen stack that is integrated in Red Hat Enterprise Linux and the stack that is integrated in SUSE Linux Enterprise Server. In this article you'll read how to set up SUSE Linux Enterprise Server as a virtualization platform.
When installing a server as the hosting hardware for several virtual machines, you have to take that into account from the beginning. First, the server itself must be powerful enough to bear all the virtual machines you want to run on it. Also, since SUSE Linux Enterprise Server is a general purpose server platform, you risk installing software that you typically wouldn't want to install when using SUSE for virtualization. The bottom line: Do not run any other services than the virtualization services in the first instance of SUSE Linux Enterprise Server that you're installing.
The first instance of your server software gets the role of the Xen domain 0. This is the operating system that is started after loading the special Xen kernel which includes the hypervisor. The domain 0 operating system has limited functions on your virtualization solution:
- It typically is responsible for the drivers used by the virtual machines
- It runs the xend process which allows you to perform virtualization management tasks
- It can run the xendomains process which allows you to start and stop domains automatically when the domain 0 is shut down.
To perform these three essential tasks as good as possible, as few services as possible should be installed on the domain 0 machine. So don't run your Apache server, DHCP server or whatever server in the domain 0, keep it to the bare minimal services.
Making the right choices
While installing your software, there are a few moments that you have to make the proper choices. The first moment is where you specify what software you want to select. The default software selection doesn't do for a virtualization server. Make sure that while installing the Domain 0 only the following package categories are selected:
- Server Base System
- High Availability (you do want your virtual machines to be highly available right?)
- Only if you want to use Virtual Manager from the Domain 0: GNOME Desktop Environment and X Window System
- Xen Virtual Machine Host Server
Apart from the software to install, you should think about the partitioning of your servers hard disk also. Typically in a data center environment, you would create a LUN to use as storage for every virtual machine. If you need to set up a stand alone machine for virtualization, it's a good idea to create a separated storage unit on hard disk for every virtual machine you are creating. LVM logical volumes are ideal for that.
After making the proper decisions about software and disk layout, complete the installation of SUSE Linux Enterprise Server. Once installed, it will be ready as your virtualization platform and you can start creating the virtual machines on it. You'll read more on that in the third part of this series.
About the author: Sander van Vugt is an author and independent technical trainer, specializing in Linux since 1994. Vugt is also a technical consultant for high-availability (HA) clustering and performance optimization, as well as an expert on SLED 10 administration.
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