EXERCISE N° 1: LINUX

Warm Up To Penguins The Zen Of Xen One of the hottest recent topics in the computer industry at this time is virtualization. Products such as VMware and Microsoft’s Virtual PC are trying to take advantage of the increasing demand to run virtual computers on top of a physical host. There are several reasons to do this. If, for example, you need to run a number of different versions of Linux from time to time, you can run them as virtual systems on top of a stable host without worrying about constantly reinstalling or corrupting your system. For businesses, virtual machines let many users share a single physical host. Because a system rarely runs at 100% load all the time, you can usually load-balance and get more bang for your hardware buck with virtual systems. Linux, of course, has a virtualization application, too: Xen. Xen is an open-source project organized by XenSource which is in turn owned by Citrix, known for GotoMyPC among others. Xen consists of a hypervisor, which is simply a software package that enables virtual hosts to run on Linux, and the virtual hosts themselves. If you’ve ever used VMware, there are some significant differences between how VMware (and Virtual PC) handles virtualization and how Xen does it. For example, VMware runs as a program (or service) that the virtual hosts run inside, but Xen actually is part of the Linux Kernel. The “host” machine is just another virtual machine (or domain, as Xen calls them) running on the hardware. Although this may seem a bit strange conceptually, it seems to pay off performance-wise.

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