If you carefully follow the recommended preliminary health check and update steps, the likelihood of a smooth migration is significantly improved. Nonetheless, any migration involves a degree of risk as Windows SBS migration makes permanent changes to your Windows SBS Source server – for example, moving e-mail accounts. Therefore, all migrations should begin with a backup of the pre-migration Source server. This backup should be sufficiently complete and fully tested.

 This article discusses using virtualization as a simple and low-risk backup method for migrating Windows SBS. A virtualized migration can be done in four stages.

  Stage 1: Virtualize Windows SBS


  1. Arrange your servers. There are three servers for this process: the Source server (SBS2003 physical), the Destination server (SBS2008 physical), and a host virtual server (SBS2003 virtual). The host virtual server should have sufficient memory and disk space to handle the SBS2003 virtual machine. If resources are tight, consider using Virtual PC 2007 for virtual machine management (http://www.microsoft.com/downloads/details.aspx?FamilyId=04D26402-3199-48A3-AFA2-2DC0B40A73B6&displaylang=en).
  2. Create a virtual image of the SBS2003 server. On the SBS2003 server, run a tool like Disk2vhd (http://technet.microsoft.com/en-us/sysinternals/ee656415.aspx) to create a physical-to- virtual image (P2V) of your SBS2003 Source server.
  3. Back up the virtual image. There are a couple reasons to do this.  First, if for some reason you want to restart your migration, this image is ready to go. Second, in Stage 3, you repurpose your existing physical SBS2003 server and reformat the drive. Should you need to go back to a pre-migration instance of your SBS2003 server, this backup provides the image to do that.
  4. Copy the SBS2003 virtual image to your virtual host server.
  5. Disconnect the SBS2003 physical server from your network.
  6. Connect the virtualized SBS2003 server to your network and check to see if it’s reachable from clients.
At this point, the virtualized SBS2003 server is now the Source server and migration will be run against this virtual server. The SBS2003 physical server remains untouched and ready to resume normal operations should you need to back out of the migration. Restoration is as simple as swapping network connections. The physical SBS2003 server is your complete and tested backup.

Stage 2: Migrate SBS2003 to SBS2008

In Stage 2, you go through the normal migration process migrating the virtualized SBS and leaving the physical SBS untouched.

 Stage 3: Install LOB applications


 In Stage 3, after reaching the point where your SBS2003 is nearly complete, you can repurpose your physical SBS2003 server for line of business (LOB) applications or for other purposes. Repurposing the physical SBS2003 server involves reformatting the system partition on the physical server. Because you created a backup of the pre-migrated SBS2003 in Stage 1, you will be able to load this image as a virtual machine any time you need to access the pre-migration SBS2003 server.

 Stage 4: Complete the Migration


 In Stage 4, you complete the migration. SBS2008 is running on a new server, LOB applications are running on the old server, and the virtual host server is freed up and ready for a new assignment.