Adlibitum

Installing Windows SBS 2008 as a Xen Fully Virtualized guest using the XEN hypervisor on CentOS 5 is fairly straight forward.

Prerequisites

Starting off we need a CentOS 5 server with at least 4GB of free RAM and enough hard disk space to support SBS. The processors must support x86 Virtualization either Intel VT or AMD V. Virtualization must also be enabled in the system BIOS. If you server supports Hyper-threading you may want to turn it off, as this might improve performance with a Windows 2008 VM. The Xen hypervisor presents the individual hyper-threaded cores as physical cores to the guest. So if you keep hyper-threading enabled you won't be able to access any of the threads anyway due to the physical 4 core limit in Windows 2008 SBS.

Install Xen

First off we install the Xen software and management GUI.

sudo yum install kernel-xen xen virt-manager xauth

Next we remove our default, non Xen kernel. This will ensure that we don't accidentally boot the wrong one.

sudo yum remove kernel

Reboot to load up the new Xen kernel

sudo reboot

Connect to Xen Server

From your workstation SSH to the Xen server. Make sure that X11 forwarding is enabled. Start up virt-manager this is the Xen Red Hat Xen management GUI.

andrew@workstation:~$ ssh -X adlibre@192.168.3.9
Last login: Mon Jan 11 14:56:59 2010 from 192.168.3.8
[adlibre@xenhost01 ~]$ virt-manager 
You are attempting to run "virt-manager" which may benefit from administrative
privileges, but more information is needed in order to do so.
Password for root: 
[adlibre@xenhost01 ~]$

Create the SBS Xen VM

You should now see the GUI startup from the previous step. Connect to Localhost and click new.

Enter the name for the server. This should correspond to the intended hostname.

Choose Fully Virtualized.

Choose Local Install Media. Select the operating system type, which in this case is Windows 2008 SBS

Choose the installation media. If you have install media on ISO choose that, otherwise CD/DVD will work fine (although slower).

Select the block device that you created earlier. In this case we've created a LVM logical volume lv_sbs_c for the SBS server's C: drive.

sudo lvcreate -L 64G -n xen_sbs_c vg_vm

Choose the Shared physical device. This will bridge the SBS Server to the local primary eth0 interface of the Xen Server.

Select the amount of RAM and the number of CPU cores to dedicate to the virtual machine. Windows SBS 2008 requires at least 4GB of RAM. In this case we've selected 5500MB which is more than enough for SBS.

Almost ready to install. Confirm that everything is ok. Then press Finish to continue onto the operating system installation.

Installing Windows SBS 2008 in a Xen VM

If you succeeded in the previous steps then the VM should automatically reboot and Windows 2008 SBS should start installing immediately.

Installing Windows 2008 within a Xen fully virtualised VM is really no different from installing on physical hardware. The following screen captures will step you through a basic install.

Select your local language.

Enter your product key.

Read and accept the license terms.

Select Custom install.

Select the virtual disk to install to.

Create a partition on the virtual disk.

Windows 2008 SBS first phase of installation begins.

System will reboot, and begin to load desktop.

Phase two of installation setup begins.

Verify the timezone and clock settings. These should be correct so long as your Xen host is set to the same timezone.

Best to click Go online and get the most recent installation updates.

Enter all your company information here. These are used for configuring and customizing SBS with your company's details.

Enter server name and domain name. NB. These cannot be changed after installation, so choose wisely. Something short and succinct.

Add a domain administrator account.

We don't care for forefront, so we do not install this. You may of course elect to install this.

Final confirmation. Double check all the details before continuing.

Sit back and relax. This is going to take a while.

Some time later we have our desktop. Installation is complete.

Note about Xen VM Hardware

Windows Server 2008 seems to work best when the disks provided to the VM are plain old IDE disks. This unfortunately means that your VM will be limited to four virtual disks, one is reserved for use by the CDROM.

— Andrew