OS Virtualization Principles


Applications of OS Virtualization

Wide range of use cases:

Virtual Machines and Hardware

Ideally virtualization is transparent to guest OSes

Paravirtualization and Xen

Xen comes from the University of Cambridge

Do not hide the virtualization from the guest OSes

Xen's performances

Borrowed from their paper at SOSP

comparative performances of Xen on bencharks

Example of use

ISP server consolidation

Smooth upgrades of critical servers

Xen for Linux

Xen is been integrated in Linux upstream

Xen Architecture

multiple domain running in Xen

Xen in Fedora

This is a work in progress

Booting Xen

From grub.conf:

title Fedora Core Xen (2.6.11-1.1369_FC4xen0)
        root (hd0,0)
	kernel /boot/xen.gz
	module /boot/vmlinuz-2.6.11-1.1369_FC4xen0 ro root=LABEL=/12 rhgb quiet selinux=0
	module /boot/initrd-2.6.11-1.1369_FC4xen0.img

Xen runs in ring 0 (approx 32MB)

Linux runs in ring 2/3

Current state (FC4)

It works with basic core tools

Future tools

Higher level tools

Xen limitations

This is a relatively new technology

Some limitations are being worked on

Xen Research

Work being done for Xen 3.0

Useful Links

Fedora Xen Kickstart

Xen FAQ Wiki

Cambridge Lab. Xen page