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

Figure 1.2 Desktop Showing Virtual Machine Manager and Virtual Machines
Introduction to Xen Virtualization 5

2
Setting Up a Virtual Machine
Host
This section documents how to set up and use SUSE Linux Enterprise 10 SP2 as a vir-
tual machine host.
In most cases, the hardware requirements for the Domain0 are the same as those for
the SUSE Linux Enterprise Server operating system, but additional CPU, disk, memory,
and network resources should be added to accommodate the resource demands of all
planned VM Guest systems.
TIP
Remember that VM Guest systems, just like physical machines, perform better
when they run on faster processors and have access to more system memory.
The following table lists the minimum hardware requirements for running a typical
virtualized environment. Additional requirements have to be added for the number and
type of the respective guest systems.
Table 2.1 Hardware Requirements
Minimum RequirementsSystem Compo-
nent
Computer with Pentium II or AMD K7 450 MHz processorComputer
512 MB of RAM for the hostMemory
Setting Up a Virtual Machine Host 7

Minimum RequirementsSystem Compo-
nent
7 GB of available disk space for the host.Free Disk Space
DVD-ROM DriveOptical Drive
20 GBHard Drive
Ethernet 100 MbpsNetwork Board
IP Address • One IP address on a subnet for the host.
• One IP address on a subnet for each VM Guest.
Xen virtualization technology is available in SUSE Linux Enterprise Server products
based on code path 10 and later. Code path 10 products include Open Enterprise Server
2 Linux, SUSE Linux Enterprise Server 10, SUSE Linux Enterprise Desktop 10, and
openSUSE 10.x.
The virtual machine host requires a number of software packages and their dependencies
to be installed. To install all necessary packages, run YaST Software Management, select
the lter Patterns and choose Xen Virtual Machine Host Server for installation.
After the Xen software is installed, restart the computer.
Updates are available through your update channel. To be sure to have the latest updates
installed, run YaST Online Update after the installation has nished.
2.1 Best Practices and Suggestions
When installing and conguring the SUSE Linux Enterprise operating system on the
host, be aware of the following best practices and suggestions:
•If the host should always run as Xen host, run YaST System >Boot Loader and
activate the Xen boot entry as default boot section.
•In YaST, click System > Boot Loader.
8Virtualization with Xen

•Change the default boot to the Xen label, then click Set as Default.
•Click Finish.
• Disable powersave functionality on the host and all guest operating systems. On
the host computer and other Linux computers, you can use the chkconfig
powersaved off command.
• Close Virtual Machine Manager if you are not actively using it and restart it when
needed. Closing Virtual Machine Manager does not affect the state of virtual ma-
chines.
•For best performance, only the applications and processes required for virtualization
should be installed on the virtual machine host.
• When using both, iSCSI and OCFS2 to host Xen images, the latency required for
OCFS2 default timeouts in SP2 may not be met. To recongure this timeout, run
/etc/init.d/o2cb configure or edit O2CB_HEARTBEAT_THRESHOLD
in the system conguration.
2.2 Setting Up a 32-Bit Domain 0 on
a 64-Bit Hypervisor
A virtual machine host running on a 64-bit platform can access much more memory
than hosts running on a 32-bit platform. However, there might be circumstances where
you want to run the 32-bit version of the SUSE® Linux operating system (as domain
0) on the 64-bit Xen hypervisor.
1On 64-bit hardware, start the 32-bit SUSE Linux operating system installation
program.
2Select Installation Settings >Software to include the Xen Virtual Machine
Host Server software package selection.
3Select Software >Software Selection and System Tasks and click Details to
view all packages.
Setting Up a Virtual Machine Host 9

4In the Filter drop-down list, select Search, then search for kernel-xen.
Make sure that kernel-xenpaeis selected for installation and that
kernel-xen is not selected.
5Complete the SUSE Linux installation program.
The installation program copies les, reboots, and prompts you for additional
setup information.
6After entering the additional setup information, log in to the computer.
7Access the SUSE Linux installation source media.
The 64-bit Xen hypervisor RPM is included in both 32-bit and 64-bit versions
of the SUSE Linux installation media.
8On the SUSE Linux installation source media, nd the x86_64 directory that
contains xen.rpm.
9Use the following command to install the RPM:
rpm -U xen.rpm --ignorearch --force
10 Edit the GRUB boot loader settings by running YaST >System >Boot Loader
or editing the le at /boot/grub/menu.lst.
11 Change Hypervisor to /boot/xen.gz.
The xen.gz hypervisor is the 64-bit hypervisor.
12 Reboot the computer.
13 During the boot process, select the Xen option from the GRUB boot loader.
14 Verify that the computer is running the 32-bit Domain 0 by entering:
uname -m
It should report a 32-bit machine name, such as i686.
15 Verify that the computer is running the 64-bit hypervisor by entering:
10 Virtualization with Xen

xm info | grep xen_caps
It should report a 64-bit Xen hypervisor, such as xen-3.0-x86_64.
2.3 Managing Domain 0 Memory
When the host is set up, a percentage of system memory is reserved for the hypervisor,
and all remaining memory is automatically allocated to Domain0.
A better solution is to set a minimum and maximum amount of memory for domain 0,
so the memory can be allocated appropriately to the hypervisor. An adequate maximum
amount would be 20 percent of the total system memory up to 2 GB. An appropriate
minimum amount would at least be 512 MB.
2.3.1 Setting a Maximum Amount of
Memory
1Determine the amount of memory to set for domain 0.
2At Domain0, type xm list to view the currently allocated memory.
3Run YaST >Boot Loader.
4Select the Xen section.
5In Additional Xen Hypervisor Parameters, add dom0_mem= mem_amount
where mem_amount is the maximum amount of memory to allocate to Do-
main0. Add K,M, or G, to specify the size, for example, dom0_mem=768M.
6Restart the computer to apply the changes.
Setting Up a Virtual Machine Host 11

2.3.2 Setting a Minimum Amount of Memory
To set a minimum amount of memory for Domain0, edit the dom0-min-mem param-
eter in the /etc/xen/xend-config.sxp le and restart xend. For more informa-
tion, see Section 4.2, “Controlling the Host by Modifying xend Settings” (page 29).
2.4 Networks Card in Fully Virtualized
Guests
In a fully virtualized guest, the default network card is an emulated Realtek network
card. However, it also possible to use the split network driver to run the communication
between Domain0 and a VM Guest. By default, both interfaces are presented to the
VM Guest, because the drivers of some operating systems require both to be present.
When using SUSE Linux Enterprise, both network cards are available for the VM Guest.
The MAC addresses of both cards are identical in this case, which leads to problems
when running the network. The following network options are available:
emulated
To use a “emulated” network interface like an emulated Realtek card, specify
type=ioemu on the vif line. In /etc/xen/vm/<configuration> this
would look like:
vif=[ 'mac=00:16:3e:62:f4:f3,type=ioemu' ]
paravirtualized
Specify the parameter type=netfront to the vif line to use the paravirtualized
network interface. In /etc/xen/vm/<configuration> this would look like:
vif=[ 'mac=00:16:3e:62:f4:f3,type=netfront' ]
emulated and paravirtualized
If the administrator should be offered both options, simply do not specify a type.
In /etc/xen/vm/<configuration> this would look like:
vif=[ 'mac=00:16:3e:62:f4:f3,model=rtl8139' ]
In this case, one of the network interfaces should be disabled.
12 Virtualization with Xen

If you are using the Virtual Machine Manager, you may also recongure the guests by
modifying the respective .sxp conguration. For more about this conguration option,
see also Section 4.3, “Conguring a Virtual Machine by Modifying its xend Settings”
(page 30).
2.5 Starting the Virtual Machine Host
If virtualization software is correctly installed, the computer boots to display the GRUB
boot loader with a Xen option on the menu. Select this option to start the virtual machine
host.
NOTE: Xen and Kdump
In Xen, the hypervisor manages the memory resource. If you need to reserve
system memory for a recovery kernel in Domain0, this memory has to be re-
served by the hypervisor. Thus, it is necessary to add the parameter
crashkernel=size@offset to the kernel line instead of using the line
with the other boot options. For more about Kdump, see also http://www
.novell.com/rc/docrepository/public/37/basedocument
.2007-09-13.2960758124/4622069_f_en.pdf.
If the Xen option is not on the GRUB menu, review the steps for installation and verify
that the GRUB boot loader has been updated. If the installation has been done without
selecting the Xen pattern, run the YaST Software Management, select the lter Patterns
and choose Xen Virtual Machine Host Server for installation.
After booting the hypervisor, the Domain0 virtual machine starts and displays its
graphical desktop environment. If you did not install a graphical desktop, the command
line environment appears.
Before starting to install virtual guests, make sure that the system time is correct. To
do this, congure NTP (Network Time Protocol) on the controlling domain:
1In YaST select Network Services >NTP Conguration.
2Select the option to automatically start the NTP daemon during boot. Provide
the IP address of an existing NTP time server, then click Finish.
Setting Up a Virtual Machine Host 13

NOTE: Time Services on Virtual Guests
Hardware clocks commonly are not very precise. All modern operating systems
try to correct the system time compared to the hardware time by means of an
additional time source. To get the correct time on all VM Guest systems, also
activate the network time services on each respective guest or make sure that
the guest uses the system time of the host. For more about Independent
Wallclocks in SUSE Linux Enterprise Server see Section 6.3.4, “Virtual Machine
Clock Settings” (page 67).
For more information about managing virtual machines, see Chapter 4, Managing a
Virtualization Environment (page 27).
14 Virtualization with Xen