Novell XEN - ADMINISTRATION User manual

SUSE Linux Enterprise
Server
www.novell.com10 SP2
July15,2008 Virtualization with Xen

Virtualization with Xen
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Contents
Preface v
1Introduction to Xen Virtualization 1
1.1 BasicComponents......................... 1
1.2 Understanding Virtualization Modes . . . . . . . . . . . . . . . . . 2
1.3 Xen Virtualization Architecture . . . . . . . . . . . . . . . . . . . . 3
1.4 The Virtual Machine Host . . . . . . . . . . . . . . . . . . . . . . 4
2Setting Up a Virtual Machine Host 7
2.1 Best Practices and Suggestions . . . . . . . . . . . . . . . . . . . . 8
2.2 Setting Up a 32-Bit Domain 0 on a 64-Bit Hypervisor . . . . . . . . . . 9
2.3 Managing Domain 0 Memory . . . . . . . . . . . . . . . . . . . . 11
2.4 Networks Card in Fully Virtualized Guests . . . . . . . . . . . . . . . 12
2.5 Starting the Virtual Machine Host . . . . . . . . . . . . . . . . . . 13
3Setting Up Virtual Machines 15
3.1 Creating a Virtual Machine . . . . . . . . . . . . . . . . . . . . . 15
3.2 Installing an Operating System . . . . . . . . . . . . . . . . . . . 17
3.3 Including Add-On Products in the Installation . . . . . . . . . . . . . 21
3.4 Using the Command Line to Create Virtual Machines . . . . . . . . . . 22
3.5 Deleting Virtual Machines . . . . . . . . . . . . . . . . . . . . . 23
3.6 Using an Existing SUSE Linux Enterprise Server Virtual Machine . . . . . 23
3.7 Troubleshooting ......................... 24
4Managing a Virtualization Environment 27
4.1 Virtual Machine Manager . . . . . . . . . . . . . . . . . . . . . 28

4.2 Controlling the Host by Modifying xend Settings . . . . . . . . . . . . 29
4.3 Conguring a Virtual Machine by Modifying its xend Settings . . . . . . 30
4.4 The xm Command ........................ 31
5Virtualization: Conguration Options and Settings 33
5.1 VirtualCDReaders........................ 33
5.2 Remote Access Methods . . . . . . . . . . . . . . . . . . . . . . 38
5.3 VNCViewer........................... 39
5.4 The Boot Loader Program . . . . . . . . . . . . . . . . . . . . . 42
5.5 Changing the Host’s Desktop from Text Mode to GUI Mode . . . . . . . 45
5.6 Paravirtual Mode and Journaling File Systems . . . . . . . . . . . . . 46
5.7 Virtual Machine Initial Startup Files . . . . . . . . . . . . . . . . . 47
5.8 Sparse Image Files and Disk Space . . . . . . . . . . . . . . . . . . 49
5.9 VirtualKeyboards......................... 49
5.10 Mapping Physical Storage to Virtual Disks . . . . . . . . . . . . . . . 52
5.11 VirtualDisks........................... 53
5.12 Migrating Virtual Machines . . . . . . . . . . . . . . . . . . . . . 54
5.13 Passing Key Combinations to Virtual Machines . . . . . . . . . . . . . 54
5.14 xm block-list Device Numbers . . . . . . . . . . . . . . . . . . . . 55
5.15 File-Backed Virtual Disks and Loopback Devices . . . . . . . . . . . . 56
5.16 Saving Virtual Machines . . . . . . . . . . . . . . . . . . . . . . 56
5.17 Restoring Virtual Machines . . . . . . . . . . . . . . . . . . . . . 57
5.18 Virtual Machine States . . . . . . . . . . . . . . . . . . . . . . . 59
6Xen Guest Systems 61
6.1 NetWare Virtual Machines . . . . . . . . . . . . . . . . . . . . . 61
6.2 OES Linux Virtual Machines . . . . . . . . . . . . . . . . . . . . . 61
6.3 SUSE Linux Virtual Machines . . . . . . . . . . . . . . . . . . . . 61
6.4 Windows Virtual Machines . . . . . . . . . . . . . . . . . . . . . 70
7Virtual Machine Drivers 71
7.1 Buying a Support Subscription . . . . . . . . . . . . . . . . . . . 72
7.2 Loading the Driver Pack . . . . . . . . . . . . . . . . . . . . . . 73
7.3 SUSE Drivers for Red Hat Enterprise Linux 4 on Xen . . . . . . . . . . 73
7.4 SUSE Drivers for Red Hat Enterprise Linux 5 on Xen . . . . . . . . . . 77
7.5 SUSE Drivers for Windows on Xen . . . . . . . . . . . . . . . . . . 81
7.6 SUSE Drivers for SUSE Linux Enterprise Server on Xen . . . . . . . . . 89

Preface
This manual offers an introduction to virtualization technology of your SUSE Linux
Enterprise Server. It features an overview of the various elds of application and instal-
lation types of each of the platforms supported by SUSE Linux Enterprise Server as
well as a short description of the installation procedure.
Quality service is also available. Experts can answer questions about installation or
conguration, make reliable security updates available, and support development
projects.
1 Feedback
We want to hear your comments and suggestions about this manual and the other doc-
umentation included with this product. Please use the User Comments feature at the
bottom of each page of the online documentation and enter your comments there.
2 Additional Documentation
For additional documentation on this product, refer to http://www.novell.com/
documentation/sles10/index.html:
Architecture-Specic Information
Architecture-specic information needed to prepare a SUSE Linux Enterprise
Server target for installation.
Installation and Administration
In-depth installation and administration for SUSE Linux Enterprise Server.
For a documentation overview on the SUSE® Linux Enterprise Desktop product, refer
to http://www.novell.com/documentation/sled10/index.html.
Documentation regarding the Open Enterprise Server 2 is found at http://www
.novell.com/documentation/oes2/index.html.

3 Documentation Conventions
The following typographical conventions are used in this manual:
•/etc/passwd: lenames and directory names
•placeholder: replace placeholder with the actual value
•PATH: the environment variable PATH
•ls,--help: commands, options, and parameters
•user: users or groups
•Alt,Alt +F1: a key to press or a key combination; keys are shown in uppercase as
on a keyboard
•File,File >Save As: menu items, buttons
• This paragraph is only relevant for the specied architectures. The arrows mark
the beginning and the end of the text block.
This paragraph is only relevant for the specied architectures. The arrows mark
the beginning and the end of the text block.
•Dancing Penguins (Chapter Penguins, ↑Another Manual): This is a reference to a
chapter in another manual.
vi Virtualization with Xen

1
Introduction to Xen
Virtualization
Virtualization of operating systems is used in many different computing areas. It nds
its applications in server consolidation, energy saving efforts, or the ability to run older
software on new hardware, for example. This chapter introduces and explains the
components and technologies you need to understand to set up and manage a Xen-based
virtualization environment.
1.1 Basic Components
The basic components of a Xen-based virtualization environment are the Xen hypervisor,
the Domain0, any number of other VM Guests, and the tools, commands, and congu-
ration les that let you manage virtualization. Collectively, the physical computer run-
ning all these components is referred to as a virtual machine host because together these
components form a platform for hosting virtual machines.
The Xen Hypervisor
The Xen hypervisor, sometimes referred to generically as a virtual machine monitor,
is an open-source software program that coordinates the low-level interaction be-
tween virtual machines and physical hardware.
The Domain0
The virtual machine host environment, also referred to as domain0 or controlling
domain, is comprised of several components, such as:
Introduction to Xen Virtualization 1

• The SUSE Linux operating system, which gives the administrator a graphical
and command line environment to manage the virtual machine host components
and its virtual machines.
NOTE
The term “Domain0” refers to a special domain that provides the manage-
ment environment. This may be run either in graphical or in command
line mode.
• The xend daemon (xend), which stores conguration information about each
virtual machine and controls how virtual machines are created and managed.
• A modied version of QEMU, which is an open-source software program that
emulates a full computer system, including a processor and various peripherals.
It provides the ability to host operating systems in full virtualization mode.
Xen-Based Virtual Machines
A Xen-based virtual machine, also referred to as a domain, consists of the follow-
ing components:
• At least one virtual disk that contains a bootable operating system. The virtual
disk can be based on a le, partition, volume, or other type of block device.
• Virtual machine conguration information, which can be modied by exporting
a text-based conguration le from xend or through Virtual Machine Manager.
Management Tools, Commands, and Conguration Files
There is a combination of GUI tools, commands, and conguration les to help
you manage and customize your virtualization environment.
1.2 Understanding Virtualization
Modes
Guest operating systems are hosted on virtual machines in either full virtualization
mode or paravirtual mode. Each virtualization mode has advantages and disadvantages.
2Virtualization with Xen

• Full virtualization mode lets virtual machines run unmodied operating systems,
such as Windows* Server 2003 and Windows XP, but requires the computer running
as the virtual machine host to support hardware-assisted virtualization technology,
such as AMD* Virtualization or Intel* Virtualization Technology.
Some guest operating systems hosted in full virtualization mode, can be congured
to run SUSE Linux Enterprise Virtual Machine Drivers instead of operating-system-
specic drivers. Running virtual machine drivers improves performance dramati-
cally on guest operating systems, such as Windows XP and Windows Server 2003.
For more information, see Chapter 7, Virtual Machine Drivers (page 71).
• Paravirtual mode does not require the host computer to support hardware-assisted
virtualization technology, but does require the guest operating system to be modied
for the virtualization environment. Typically, operating systems running in paravir-
tual mode enjoy better performance than those requiring full virtualization mode.
Operating systems currently modied to run in paravirtual mode are referred to as
paravirtualized operating systems and include SUSE Linux Enterprise Server 10
and NetWare® 6.5 SP7.
1.3 Xen Virtualization Architecture
The following graphic depicts a virtual machine host with four virtual machines. The
Xen hypervisor is shown as running directly on the physical hardware platform. Note,
that the controlling domain is also just a virtual machine, although it has several addi-
tional management tasks compared to all other virtual machines.
Introduction to Xen Virtualization 3

Figure 1.1 Virtualization Architecture
On the left, the virtual machine host’s Domain0 is shown running the SUSE Linux op-
erating system. The two virtual machines shown in the middle are running paravirtualized
operating systems. The virtual machine on the right shows a fully virtual machine run-
ning an unmodied operating system, such as Windows Server 2003 or Windows XP.
1.4 The Virtual Machine Host
After you install the virtualization components and reboot the computer, the GRUB
boot loader menu should display a Xen menu option. Selecting the Xen menu option
loads the Xen hypervisor and starts the Domain0 running the SUSE Linux operating
system.
Running on domain 0, the SUSE Linux operating system displays the installed text
console or desktop environment, such as GNOME or KDE. When opened, each virtual
machine is displayed in its own window inside the controlling domain 0.
4Virtualization with Xen