SUSE Linux Enterprise
www.novell.com10 SP2
October27,2009 Virtualization with Xen
Server
Virtualization with Xen
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Contents
Preface v
1 Introduction to Xen Virtualization 1
1.1 Basic Components . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Understanding Virtualization Modes . . . . . . . . . . . . . . . . . 2
1.3 Xen Virtualization Architecture . . . . . . . . . . . . . . . . . . . . 3
1.4 The Virtual Machine Host . . . . . . . . . . . . . . . . . . . . . . 4
2 Setting 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
3 Setting 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
4 Managing a Virtualization Environment 27
4.1 Virtual Machine Manager . . . . . . . . . . . . . . . . . . . . . 28
4.2 Controlling the Host by Modifying xend Settings . . . . . . . . . . . . 29
4.3 Conguring a Virtual Machine by Modifying its xend Settings . . . . . . 30
4.4
The xm Command . . . . . . . . . . . . . . . . . . . . . . . . 31
5 Virtualization: Conguration Options and Settings 33
5.1 Virtual CD Readers . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2 Remote Access Methods . . . . . . . . . . . . . . . . . . . . . . 38
5.3 VNC Viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 Virtual Keyboards . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.10 Mapping Physical Storage to Virtual Disks . . . . . . . . . . . . . . . 52
5.11 Virtual Disks . . . . . . . . . . . . . . . . . . . . . . . . . . . 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
6 Xen 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
7 Virtual 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 installation 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
conguration, 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 documentation 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-Specic Information
Architecture-specic 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 specied architectures. The arrows mark
the beginning and the end of the text block.
This paragraph is only relevant for the specied 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
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 conguration les that let you manage virtualization. Collectively, the physical computer running 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 between 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:
1
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 management environment. This may be run either in graphical or in command
line mode.
• The xend daemon (xend), which stores conguration information about each
virtual machine and controls how virtual machines are created and managed.
• A modied 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 following 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 conguration information, which can be modied by exporting
a text-based conguration le from xend or through Virtual Machine Manager.
Management Tools, Commands, and Conguration Files
There is a combination of GUI tools, commands, and conguration 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.
2 Virtualization with Xen
• Full virtualization mode lets virtual machines run unmodied 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 congured
to run SUSE Linux Enterprise Virtual Machine Drivers instead of operating-systemspecic drivers. Running virtual machine drivers improves performance dramatically 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 modied
for the virtualization environment. Typically, operating systems running in paravirtual mode enjoy better performance than those requiring full virtualization mode.
Operating systems currently modied 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 additional management tasks compared to all other virtual machines.
Introduction to Xen Virtualization 3
Figure 1.1
On the left, the virtual machine host’s Domain0 is shown running the SUSE Linux operating 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 running an unmodied operating system, such as Windows Server 2003 or Windows XP.
Virtualization Architecture
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.
4 Virtualization with Xen
Figure 1.2
Desktop Showing Virtual Machine Manager and Virtual Machines
Introduction to Xen Virtualization 5
Setting Up a Virtual Machine Host
This section documents how to set up and use SUSE Linux Enterprise 10 SP2 as a virtual 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
nent
Hardware Requirements
Minimum RequirementsSystem Compo-
2
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 conguring 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.
8 Virtualization 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 machines.
• 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 recongure this timeout, run
/etc/init.d/o2cb configure or edit O2CB_HEARTBEAT_THRESHOLD
in the system conguration.
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.
On 64-bit hardware, start the 32-bit SUSE Linux operating system installation
1
program.
Select Installation Settings > Software to include the Xen Virtual Machine
2
Host Server software package selection.
Select Software > Software Selection and System Tasks and click Details to
3
view all packages.
Setting Up a Virtual Machine Host 9
4
In 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.
Complete the SUSE Linux installation program.
5
The installation program copies les, reboots, and prompts you for additional
setup information.
After entering the additional setup information, log in to the computer.
6
Access the SUSE Linux installation source media.
7
The 64-bit Xen hypervisor RPM is included in both 32-bit and 64-bit versions
of the SUSE Linux installation media.
On the SUSE Linux installation source media, nd the x86_64 directory that
8
contains xen.rpm.
Use the following command to install the RPM:
9
rpm -U xen.rpm --ignorearch --force
Edit the GRUB boot loader settings by running YaST > System > Boot Loader
10
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.
Reboot the computer.
12
During the boot process, select the Xen option from the GRUB boot loader.
13
Verify that the computer is running the 32-bit Domain 0 by entering:
14
uname -m
It should report a 32-bit machine name, such as i686.
10 Virtualization with Xen
Verify that the computer is running the 64-bit hypervisor by entering:
15
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
Determine the amount of memory to set for domain 0.
1
2
At Domain0, type xm list to view the currently allocated memory.
Run YaST > Boot Loader.
3
Select the Xen section.
4
5
In Additional Xen Hypervisor Parameters, add dom0_mem= mem_amount
where mem_amount is the maximum amount of memory to allocate to Domain0. Add K, M, or G, to specify the size, for example, dom0_mem=768M.
Restart the computer to apply the changes.
6
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 parameter 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 recongure the guests by
modifying the respective .sxp conguration. For more about this conguration option,
see also Section 4.3, “Conguring 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 reserved 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, congure NTP (Network Time Protocol) on the controlling domain:
In YaST select Network Services > NTP Conguration.
1
Select the option to automatically start the NTP daemon during boot. Provide
2
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
Setting Up Virtual Machines
A virtual machine is comprised of data and operating system les that dene the virtual
environment. Virtual machines are hosted and controlled by the virtual machine host.
This section provides generalized instructions for installing virtual machines.
Virtual machines have few if any requirements above those required to run the operating
system. If the operating system has not been optimized for the virtual machine host
environment, the unmodied OS can run only on hardware-assisted virtualization
computer hardware, in full virtualization mode, and requires specic device drivers to
be loaded.
You should be aware of any licensing issues related to running a single licensed copy
of an operating system on multiple virtual machines. Consult the operating system license
agreement for more information.
NOTE: Virtual Machine Architectures
The virtual machine host runs only on x86, AMD64 and Intel 64 hardware. It
does not run on other system architectures such as Itanium, or POWER. A 64bit virtual machine host can also run a 32-bit operating system, while a 32-bit
host cannot run a 64-bit client. This holds true for both, the controlling domain
and all further guests.
3
3.1 Creating a Virtual Machine
Before creating a virtual machine, you need the following:
Setting Up Virtual Machines 15
•
Install a host server as described in Chapter 2, Setting Up a Virtual Machine Host
(page 7).
• If you want to use an automated installation le (AutoYaST, NetWare® Response
File, or RedHat Kickstart), you should create and download it to a directory on the
host machine server or make it available on the network.
• For NetWare and OES Linux virtual machines, you need a static IP address for
each virtual machine you create.
• If you are installing Open Enterprise Server (OES) 2 Linux, you need a network
installation source for OES 2 Linux software including the SUSE Linux Enterprise
Server 10 SP2 media and the OES 2 Linux add-on CD. For procedures to create
the installation sources, see "Setting Up the Server Holding the Installation Sources"
in the SUSE Linux Enterprise Server 10 Installation and Administration Guide
[http://www.novell.com/documentation/sles10/sles_admin/
data/sec_deployment_remoteinst_instserver.html]
For further prerequisites, consult the manuals of the respective operating system to install.
The Create Virtual Machine Wizard helps you through the steps required to create a
virtual machine and install its operating system. The information that follows is generalized for installing any operating system. In addition to these instructions, you should
consult Chapter 6, Xen Guest Systems (page 61) for information specic to the operating
system you are installing.
The actual conguration les for the Xen guests are stored at /etc/xen/vm/. The
default location for image les is /var/lib/xen/images.
Launch the Create Virtual Machine Wizard by using one of the following methods:
•
From the virtualization host server desktop, click YaST > Virtualization > Create
Virtual Machine
•
From within Virtual Machine Manager, click New.
•
At the command line, enter vm-install.
16 Virtualization with Xen
If the wizard does not appear or the vm-install command does not work, review
the process of installing and starting the virtualization host server. The virtualization
software might not be installed properly.
3.2 Installing an Operating System
You can choose to run an installation program or choose a disk or disk image that already
has an installed and bootable operating system.
Figure 3.1
If you choose to run an installation program, you are presented with a list of operating
systems. Select the one you want to install.
The Summary page shows you a summary of the virtual machine you are creating. You
can click on any of the headings to edit the information. As you edit the information in
the Summary, consult Chapter 6, Xen Guest Systems (page 61) for instructions specic
to the operating system you are installing.
Installing an Operating System
Setting Up Virtual Machines 17
Figure 3.2
Information about the following operating systems is included:
• OES NetWare Virtual Machines, see Section 6.1, “NetWare Virtual Machines”
(page 61).
• OES Linux Virtual Machines, see Section 6.2, “OES Linux Virtual Machines”
(page 61).
Summary
• SUSE Linux Virtual Machines, see Section 6.3, “SUSE Linux Virtual Machines”
(page 61).
• Windows Virtual Machines, see Section 6.4, “Windows Virtual Machines”
(page 70).
When running through the creation of a VM Guest, the following steps have to be accomplished:
Select if the VM Guest should run as full or paravirtualized guest.
1
If your computer supports hardware-assisted virtualization, you can create a virtual machine that runs in fully virtual mode. If you are installing an operating
system that is modied for virtualization, you can create a virtual machine that
runs in paravirtual mode. For more information about virtualization modes, see
Section 1.2, “Understanding Virtualization Modes” (page 2).
18 Virtualization with Xen
Each virtual machine must have a unique name. The name entered on this page
2
is used to create and name the virtual machine’s conguration le. The conguration le contains parameters that dene the virtual machine and is saved to the
/etc/xen/vm/ directory.
The Hardware page allows you to specify the amount of memory and number of
3
virtual processors for your virtual machine.
Initial Memory
The amount of memory initially allocated to the virtual machine (specied
in megabytes).
Maximum Memory
The largest amount of memory the virtual machine will ever need.
Virtual Processors
If desired, you can specify that the virtual machine has more virtual CPUs
than the number of physical CPUs. You can specify up to 32 virtual CPUs:
however, for best performance, the number of virtual processors should be
less than or equal to the number of physical processors.
Select the graphics mode to use:
4
No Graphics Support
The virtual machine operates like a server without a monitor. You can access
the operating system through operating system supported services, such as
SSH or VNC.
Paravirtualized Graphics Adapter
Requires that an appropriate graphics driver is installed in the operating
system.
A virtual machine must have at least one virtual disk. Virtual disks can be:
5
• File backed, which means that the virtual disk is a single image le on a
larger physical disk.
• A sparse image le, which means that the virtual disk is a single image le,
but the space is not preallocated.
• Congured from a block device, such as an entire disk, partition, or volume.
Setting Up Virtual Machines 19
For best performance, create each virtual disk from an entire disk or a partition.
For the next best performance, create an image le but do not create it as a sparse
image le. A virtual disk based on a sparse image le delivers the most diskspace exibility but slows installation and disk access speeds.
By default, a single, le-backed virtual disk is created as a sparse image le in
/var/lib/xen/images/vm_name where vm_name is the name of the
virtual machine. You can change this conguration to meet your specic requirements.
If you want to install from DVD or CD-Rom, add the drive to the list of available
6
hard disks. To learn about device names of the available optical drives, run
hwinfo --cdrom and search for the line starting with Device File:. Add
this device le to the available hard disks of the VM Guest.
By default, a single virtual network card is created for the virtual machine. It has
7
a randomly generated MAC address that you can change to t your desired conguration. The virtual network card will be attached to a default bridge congured
in the host. You can also create additional virtual network cards in the Network
Adapters page of vm-install.
NOTE: Using Arbitrary Bridge Names
If installing a fully virtualized guest and you are using a bridge name that
is different than the default names, explicitly specify the bridge by selecting the bridge name from the Source menu on the Virtual Network
Adapter page. Paravirtual guests by denition are aware they are running
on a virtualization platform and therefore, do not need to have the bridge
explicitly specied, thus leaving Source as Default will sufce.
The operating system can be installed from a CD/DVD device or an ISO image
8
le. In addition, if you are installing a SUSE Linux operating system, you can
install the operating system from a network installation source.
If you are installing a paravirtual machine's operating system from CD, you
should remove the virtual CD reader from the virtual machine after completing
the installation, because the virtual machine assumes that the original CD is still
in the CD reader, even if it is ejected. If it is ejected, the virtual machine cannot
access the CD (or any other newly inserted CD) and receives I/O errors.
20 Virtualization with Xen
WARNING: Changing CD-Roms
On paravirtual guests, it is currently not possible to go on with the installation of a system after changing the CD-Rom. Instead, you should use a
DVD or a network based installation. For a workaround to this problem,
see Section 5.1.1, “Virtual CD Readers on Paravirtual Machines” (page 34).
If the installation program is capable of recognizing an installation prole, response le, or script, you can automate the installation settings by specifying the
location of the prole, response le, or script you want to use. For example,
SUSE Linux uses an AutoYaST prole, NetWare uses a NetWare Response File,
and Red Hat uses a Kickstart le to move through the installation screens with
no interaction.
You can also pass instructions to the kernel at install time by entering parameters
for the Additional Arguments eld. These arguments may either be kernel options,
or options for linuxrc. More information about linuxrc can be found at
http://www.novell.com/documentation/sles10/sles_admin/
data/sec_deployment_remoteinst_bootinst.html
If all the information on the Summary screen is correct, click OK to create the virtual
machine. A TightVNC screen appears and at this point you begin the installation of
your OS. From this point on, follow the regular installation instructions for installing
your OS. More information for any instructions that might be different for installing
your OS in a virtualized environment may be found in Chapter 6, Xen Guest Systems
(page 61).
3.3 Including Add-On Products in the Installation
In order to include an Add-On product in the installation process of a VM Guest, it is
necessary to provide the installation system with both, the standard installation images
and the image for the Add-On product.
First, add the system disk, the SUSE Linux Enterprise Server 10 SP2 installation image
and the physical CD-Rom or Add-On image as disks to the VM Guest. For example,
you may have:
Setting Up Virtual Machines 21
xvda
Main system disk.
xvdb
ISO image of the installation medium.
xvdc
ISO image of the Add-On product.
During the installation, add the Add-On product to the installation by entering the device
path. Commonly, this path looks like hd:///?device=/dev/xvd<letter>. In
the special example with “xvdc” as Add-On product, this would look like:
hd:///?device=/dev/xvdc
3.4 Using the Command Line to Create Virtual Machines
From the command line, you can enter vm-install to run a text version of the Create
Virtual Machine Wizard. The text version of the wizard is helpful in environments
without a graphical user interface. This command defaults to using a graphical user
interface if available and if no options were given on the command line.
For information on scripting a virtual machine installation, see the man pages of
vm-install and vm-install-jobs.
22 Virtualization with Xen
Figure 3.3
Command Line Interface
3.5 Deleting Virtual Machines
When you use Virtual Machine Manager or the xm command to delete a virtual machine,
it no longer appears as a virtual machine, but its initial startup le and virtual disks are
not automatically deleted.
To delete all components of a virtual machine congured with a le-backed virtual
disk, you must manually delete its virtual disk image le (/var/lib/xen/images/)
and its initial startup le (/etc/xen/vm).
3.6 Using an Existing SUSE Linux Enterprise Server Virtual Machine
In SUSE Linux Enterprise Server 10, the device naming is different than the device
naming of SUSE Linux Enterprise Server 9. Therefore, a SUSE Linux Enterprise
Setting Up Virtual Machines 23
Server 9 VM Guest will not be able to nd its root le system when running on a SUSE
Linux Enterprise Server 10 VM Host Server.
To be able to still boot the system, you must know which device is used for the root
partition of your virtual system. For example, hdaxx will be changed to xvdaxx
where xx is the partition number.
When booting the system, you have to append an extra root option to the kernel command line, that tells the system about its root le system. If your VM Guest used to
live on /dev/hda2, append the string root=/dev/xvda2 to the kernel command
line. This option should enable you to boot the system, although additional lesystems
still will not be available to the system.
To make all the needed le systems available to the VM Guest, do the following:
In order to have a valid initial ramdisk that knows about the new location of the root
lesystem, run the command mkinitrd.
1
Start the VM Guest with the extra root= command line as explained above.
2
Log into the system as user root.
3
Edit the le /etc/fstab and correct all device entries.
4
Edit the virtual machine’s /boot/grub/menu.lst le. At the kernel line,
x the root= and the resume= parameters according the new naming schema.
Reboot the virtual machine.
5
3.7 Troubleshooting
In some circumstances, problems may occur during the installation of the VM Guest.
This section describes some known problems and their solutions.
During boot, the system hangs
The software I/O translation buffer allocates a large chunk of low memory early
in the bootstrap process. If the requests for memory exceed the size of the buffer
it usually results in a hung boot process. To check if this is the case, switch to
console 10 and check the output there for a message similar to
24 Virtualization with Xen
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