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
Thanks, this was what I needed to get our W2K8 office server up and running on our xen host.
Hi thanks, its very interesting... doubt about how to access virtual os from any remote host machine?
Thanks for info. It was very helpful. We set up our Win2k3 server SATA drives as IDE drives and seemed have problems copying large files onto them. Basically, the drives are very slow and the network connection cuts out when larges files are copied from Win2k3 clients to the server. We noticed the vcpus (2 out of 8) are running pretty high and we notice a performance degradation on our Exchange server even though they are on different physical drives. Did you find setting up the storage as SCSI drives problematic? Instability or performance issues? I thought we try setting up the drives as SCSI since we are having problems with IDE set up. Thanks.
HS
@HS
I'm not sure why you experienced performance issues. Generally with virtualised systems, the disk I/O subsystem is a bottleneck. Exchange generally needs a LOT of I/O, unless there are only a few users. So this means provisioning the server with lots of fast disk.
@prabu
You can access the machine via Remote desktop, or connect to the VM console using the console manager, or even VNC, if Xen is configured to support VNC consoles.