Virtualization and Linux--A Primer
Why the Hooplah?
Virtualization is the hot buzzword these days. Everyone is all excited over this latest, greatest miracle computer cure. It transforms your computing infrastructure into a shiny empire of efficiency and contentment, makes you an IT Hero and it repairs bad haircuts. So what are you waiting for? Hop on the virtualization bandwagon quickly, before it goes away forever!
Aw, I knew you wouldn't be that gullible. You want some actual data and information before making that kind of decision. Well, OK then. Let us therefore examine this whole virtualization phenomenon. We'll take a peek at running User-Mode Linux, Xen, VMWare, chroot jails, Ensim, and OpenVZ on Linux. (Yes, I know there are others, and you're welcome to email me about them.)
Typically, virtualization means you have a single host operating system than runs multiple instances of the same guest operating system, or mixing different guest operating systems. Chroot jails don't fit either category, but they do fit the overall concept of running multiple services on the same box in safely isolated environments.
First of all, why? What's the fuss? Why is this even worth thinking about? The short answer is "under-utilized hardware." The second short answer is "consolidation."
System and network administrators struggle with the issue of how many services to put on a single machine, especially an Internet-facing machine. Physical separation adds security - if one service is compromised, it won't take down others. A hardware failure affects only a single service. But the price is added complexity, larger space requirements and more energy consumption. x86 hardware gives so much bang for the buck that a lot of machines are running at little better than idle speed. With affordable multi-processor machines and multi-core processors parading their enticing selves all over the places, what you we going to do with all that horsepower?