Virtual Server 2005 includes a type of virtual hard drive (VHD) called a Differencing Disk. A Differencing Disk is a disk that holds changes made to the base, or parent disk, without affecting the parent disk. You can use one parent disk for multiple servers that have differencing disks. When combined with Sysprep you can have a new virtual machine up and running, with all the service packs, hotfixes and tools, in minutes rather than hours.
In
Virtual Server and Differencing Disks Pt.1 - Sysprep we created the Sysprep image. Now we can create a new virtual machine using a Differencing VHD. Create a new VM choosing to Attach a virtual hard disk later.
Now with the virtual machine created, we need to create a the differencing disk and add it to the newly created virtual machine. Under the Virtual Disk header on the administration webpage, select Create and then choose Differencing Virtual Hard Disk.
Choose the new VM from the drop-down list then name the VHD. Next select the parent disk from the drop-down list and select create.
Now all that is left is to add the Differencing VHD to the new VM and we are set. Go back to the configuration page for the new VM and click on the Hard Disk link. Next click the Add button. Select the Known Virtual Hard Disk from the drop down, verify the path is correct and click OK.
Start the new VM, complete the mini-setup and you are ready to go.