Xen Virtualization Last Update Copyright 2011 Kenneth M. Chipps Ph.D.

Objectives of This Section Learn –About the Xen approach to virtualization 2 Copyright 2011 Kenneth M. Chipps Ph.D.

Xen Virtualization This will be a basic discussion of Xen virtualization mostly because it is based on Linux Despite using Linux off and on since 1995 I really do not like it It is just a pain to install and use compared to Windows as we will see another example of here Copyright 2011 Kenneth M. Chipps Ph.D. 3

Xen Virtualization I realize the ability to script actions is useful in large environments such as one would see in virtualization, but I still find Linux to be irritating every time I use it So to really find out about Xen I suggest consulting this book Copyright 2011 Kenneth M. Chipps Ph.D. 4

Xen Virtualization The Book of Xen by Takemura and Crawford It has a few years on it now, but it is still very useful as the move from version 3 to 4 does not appear to have fundamentally altered how Xen works Copyright 2011 Kenneth M. Chipps Ph.D. 5

Xen Virtualization There is Xen and there is Xen Here we are talking about the free version from There is another set of programs both free and paid available from Citrix who purchased Xen back in 2007 Copyright 2011 Kenneth M. Chipps Ph.D. 6

Xen Virtualization They left the open source product we are covering here The also offer a free version called XenServer Copyright 2011 Kenneth M. Chipps Ph.D. 7

Xen Architecture Xen is a bare metal virtualization method It has three main layers –Xen Hypervisor –Domain 0 or dom0 –Domain U or domU Copyright 2011 Kenneth M. Chipps Ph.D. 8

Xen Architecture The Xen hypervisor takes control of the physical hardware This is a paravirtualized hypervisor The dom0 partition is used to manage the guest operating systems stored in the various domU partitions A modified Linux kernel is used by dom0 itself Copyright 2011 Kenneth M. Chipps Ph.D. 9

Xen Architecture A modified or unmodified operating system may be used in domU When modified these are called PV guests as they are paravirtualized They have no direct access to the hardware Linux and the various versions of Unix fit in this category Copyright 2011 Kenneth M. Chipps Ph.D. 10

Xen Architecture Windows can be run unmodified This is a HVM guest as they are fully virtualized Copyright 2011 Kenneth M. Chipps Ph.D. 11

Xen Architecture Xen calls their hypervisor a thin hypervisor as it does not use device drivers It uses dom0 for this In contrast VMware does use device drivers Microsoft follows the Xen model Here are the diagrams they show illustrating this Copyright 2011 Kenneth M. Chipps Ph.D. 12

Xen Architecture Copyright 2011 Kenneth M. Chipps Ph.D. 13

VMware Architecture Copyright 2011 Kenneth M. Chipps Ph.D. 14

Microsoft Architecture Copyright 2011 Kenneth M. Chipps Ph.D. 15

Xen Installation Let’s install Xen now This example uses CentOS 5.5 installed with the server defaults CentOS provides built-in Xen support Copyright 2011 Kenneth M. Chipps Ph.D. 16

CentOS Installation To install CentOS –Boot from disk with the CentOS IOS on it –Install it as you prefer –The book and I used Default partitioning –Which creates a small /boot partition and devotes the rest of the drive to an LVM group, with a logical volume for swap and a volume for root Default configuration for the GRUB boot loader Default network configuration Copyright 2011 Kenneth M. Chipps Ph.D. 17

CentOS Installation Next select the time zone Enter a password Select the packages to load –Required »Virtualization server package group –Not required but as I am a GUI sort of person »GNOME desktop »Server-gui –Select Next –After the reboot the normal Linux load occurs Copyright 2011 Kenneth M. Chipps Ph.D. 18

CentOS Installation After the ISO boots Press Enter to use the graphical installation process The load begins showing the usually Linux stuff ending in a character based GUI of sorts Bypass the media test by selecting Skip A real GUI appears Copyright 2011 Kenneth M. Chipps Ph.D. 19

CentOS Installation Select Next Select the language Select the keyboard language Setup the desired partitions in this case the default is used The partition layout is shown Select Next Copyright 2011 Kenneth M. Chipps Ph.D. 20

CentOS Installation The GRUB setup screen is shown Select Next The network setup screen is shown Select Next The timezone screen is show Select the timezone then Next Enter a password Select Next Copyright 2011 Kenneth M. Chipps Ph.D. 21

Xen Installation Select the packages to load –In this case I selected Desktop – GNOME Server – GUI Virtualization Select Next The installation is ready to begin Select Next The installation commences Copyright 2011 Kenneth M. Chipps Ph.D. 22

CentOS Installation At its conclusion Click Reboot Remove the media from the drive Go through the setup steps for CentOS In this case it asks you to setup –A firewall –Security Enhanced Linux –Kdump –The date and time Copyright 2011 Kenneth M. Chipps Ph.D. 23

CentOS Installation –Create a regular user account –Setup the sound card –Load anything else Click Finish My setup required a reboot Login Copyright 2011 Kenneth M. Chipps Ph.D. 24

Xen Installation And we have a bare metal hypervisor with in this case a GUI interface as I am a GUI person Select from the Applications menu System Tools Virtual Machine Manager –This is virt-manager We see the dom0 guest operating system shown as Domain-0 Wasn’t that easy, even for Linux Copyright 2011 Kenneth M. Chipps Ph.D. 25

Creating a Virtual Machine Now let’s create a virtual machine Select localhost Click New This starts the virtual machine wizard One of the little Linux oddities pops up here, which serves to remind me why I hate Linux Copyright 2011 Kenneth M. Chipps Ph.D. 26

Creating a Virtual Machine You cannot load a paravirtualized guest operating system from a disc in a drive or from an IOS file on the physical hard drive Only a fully virtualized operating system such as Windows can be Copyright 2011 Kenneth M. Chipps Ph.D. 27

Creating a Virtual Machine Linux just drives me crazy So instead of just loading the same CentOS that was just used to create the hypervisor we will load Windows XP Pro instead Place it in the drive Back to the wizard Copyright 2011 Kenneth M. Chipps Ph.D. 28

Creating a Virtual Machine Enter a name for the domU Select Fully virtualized Select Local install media Tell it the OS Type Tell it the OS Variant Browse to the ISO file location Tell it where to store the virtual machine Tell it how to setup the virtual network Copyright 2011 Kenneth M. Chipps Ph.D. 29

Creating a Virtual Machine Adjust the memory and CPU allocations if desired Click Finish The virtual machine is created The operating system is installed in it Part way through the Windows installation the virtual machine window will appear where you must click Run to let it finish the installation Copyright 2011 Kenneth M. Chipps Ph.D. 30

Creating a Virtual Machine Now wasn’t that easy as well despite the obstacles Linux placed in our way Copyright 2011 Kenneth M. Chipps Ph.D. 31