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Top 10 Linux Virtualization Software

Virtualization is the latest buzz word. You may wonder computers are getting cheaper every day, why should I care and why should I use virtualization? Virtualization is a broad term that refers to the abstraction of computer resources such as:

  1. Platform Virtualization
  2. Resource Virtualization
  3. Storage Virtualization
  4. Network Virtualization
  5. Desktop Virtualization

This article describes why you need virtualization and list commonly used FOSS and proprietary Linux virtualization software.
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Virtualization: Run Windows and Linux at One Place

I've used VMWARE ESX / Xen paravirtualization, Virtuozzo, Solaris Containers, and FreeBSD Jails as os level virtualization. Virutalbox is another full virtualization solution. Presently, VirtualBox runs on Windows, Linux and Macintosh hosts and supports a large number of guest operating systems including but not limited to Windows (NT 4.0, 2000, XP, Server 2003, Vista), DOS/Windows 3.x, Linux (2.4 and 2.6), and OpenBSD.

Virtualization: Run Windows and Linux at One Place

Rakesh has published a small article about VirtualBox Virtualization software. Both Windows and Linux can be run together simultaneously, and you don't even need to switch between the two. With the seamless Windows feature of the latest version of VirtualBox virtualization software, you can seamlesssly run both Windows and Linux applications from the same desktop interface. This has been made possible by the combined efforts of VirtualBox and SeamlessRDP that is meant for seamless Windows support for rdesktop.

=> How to run Windows and Linux at one place? [ciol.com]

Download of the day: Oracle VM

Virtualization is the process of abstracting computing resources such that multiple operating system and application images can share a single physical server, bringing significant cost-of-ownership and manageability benefits. Through its Oracle VM product, Oracle offers scalable, low-cost server virtualization for heterogeneous applications.

Oracle VM is free server virtualization software that fully supports both Oracle and non-Oracle applications, and is three times more efficient than other server virtualization products.
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XEN Server Status Monitoring Command Cheat Sheet

The xm command is the main command line interface for managing Xen guest domains. The program can be used to create, pause, and shutdown domains. It can also be used to list current domains, enable or pin VCPUs, and attach or detach virtual block devices.

Please note that before running any one of the following command you must run xend ( Xen control daemon aka service) and must be run as privileged user. Running xm command as non root will return an error.

I hope following XEN status monitoring cheat sheet will save your time.
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How to: Install and Setup XEN Virtualization Software on CentOS Linux 5

One of our regular reader asks:

I'm using CentOS Linux 5 server. How do I set up Xen on Linux ? How do I install guest VPS oses such as Fedora or Windows 2000 or Debian Linux inside XEN?

Xen is a free open source software virtual machine monitor for Intel / PowerPC architectures. It is software that runs on a host operating system and allows several guest operating systems to be run on top of the host on the same computer hardware at the same time (just like VMWare software). Luckily Installing and managing XEN is quite easy under CentOS 5 Linux.

Login as the root and type the following commands:
# yum install xen virt-manager kernel-xen
# chkconfig xend on
# reboot

Make sure you boot CentOS server using XEN kernel.

How do I install NetBSD / any Linux distro / Windows 2000 inside XEN?

Simply use gui tool called virt-manager:
# virt-manager &

CentOS XEN Virtual machine manager

CentOS XEN Virtual machine manager

Now just follow on screen instructions to setup new guest operating systems (VPS oses). virt-manager is Xen Management Consoles software. It can perform the common tasks of administering a Xen host such as configuring, starting, monitoring and stopping of Xen guests oses. Please note that above instructions also works on

  • RHEL 5
  • Fedora Linux 7

Installing CentOS 5.3 guest using the Internet

virt-install is a command line tool for provisioning new virtual machines using the "libvirt" hypervisor management library. Type the following command to install CentOS v5.3 64 bit as guest operating system in /vm:
# mkdir /vm
If you are using SELinux, enter:
# semanage fcontext -a -t xen_image_t "/vm(/.*)?"
# restorecon -R /vm
# ls -dZ /vm

Above will provide security context of Xen images. Finally, install CentOS 5.3 using the Internet mirror:
# virt-install \
--paravirt \
--name webserver01 \
--ram 512 \
--file /vm/webserver.nixcraft.com.img \
--file-size 10 \
--nographics \
--location http://mirrors.kernel.org/centos/5.3/os/x86_64/

Above will CentOS as a paravirtualized Xen guest, with 512 MB of RAM, a 10 GB of disk, and from a web server, in text-only mode. You need to just follow on screen instructions.

Fig.01: Centos Xen Virtualization Installation

Fig.01: Centos Xen Virtualization Installation

Once installed you can use xm command to list, start, stop and manage xen vps:
# xen list
Attach console to domain / guest called webserver01:
# xm console webserver01
See xm command cheat sheet.

Installing CentOS 5.3 guest using DVD

Install a CentOS guest, using LVM partition, virtual networking, booting from the host CDROM, using VNC server/viewer (insert DVD into drive):
# virt-install \
--connect qemu:///system \
--name mailserver
--ram 500 \
--file /dev/HostVG/mailserver.cyberciti.biz \
--network network:default \
--accelerate \
--vnc \
--cdrom /dev/cdrom

Note you need qemu and virt-viewer installed on the host system.

Installing Fedora guest using DVD iso image stored on hard disk

Install a Fedora Linux, with a real partition (/dev/sdc), using a local DVD ISO image:
# virt-install \
--name www2 \
--ram 1000 \
--file /dev/sdc \
--network bridge:eth1 \
--cdrom /tmp/fedorabootdvd.iso

Further readings:

Howto: Create Shared Storage on Suse Linux using OCFS2 and Xen Virtualization

Arun Singh shows us how to create shared storage on SUSE Linux Enterprise Server 10 using OCFS2 (Oracle Cluster File System v2 for shared storage) and Xen Virtualization technology. Enterprise grade shared storage can cost you lots of money but here no real expensive shared storage used. The information provided here works with real shared storage as well:

This paper is to help you to understand the steps involved in creating shared storage without using expensive shared storage. Using this information you can create shared storage used by all xen guest OS and Host, avoiding copying of files between guest OS's. Hope you will find this paper useful.

You can easily port instructions to Redhat or any other Linux distro without a problem. You can also use Redhat's Global File System (GFS) too. We often use Fibre Channel or iSCSI, devices for GFS shared storage.

Creating shared storage on SUSE Linux Enterprise Server 10 using Xen and OCFS2 [novell.com]

On a related note there is also article about creating a highly available VMware Server environment on a Debian Etch system.

Download OpenSuse Linux 10.2

Download OpenSuse

Update: Download latest OpenSuse Linux version 10.3.

I know most of us tired of answering questions about the Microsoft-Novell deal.. but OpenSuse Linux 10.2 is here....

openSUSE is a community project, sponsored by Novell, to develop and maintain SUSE Linux components (such as YaST).

Some of the Good application included:
* AppArmor: gives certain applications rights based on how they run and interact with the environment.
* YaST: a system management application
* Xen: virtualization software
* The KDE and GNOME desktop environments and many more

It's available for download on http://download.openSUSE.org in x86, x86-64, and ppc versions - via ftp from our mirrors and bittorrent.

Read more at OpenSuse mailing list...