Alex @ Net

This article will help you install Microsoft Virtual PC and create an image of the Windows Vista operation system.

Microsoft Virtual PC is a very interesting application. It creates a virtual computer on your PC and this computer can host another operation system. In some situations it is very useful. For example, if you like to try new interesting programs you may notice that some of them may damage file associations, leave files and registry entries after uninstallation, create working folders in documents folder and so on. The solution may be to install and run the software in the sandbox and then rollback the changes – all of this is possible with Virtual PC.

Virtual PC also helps you investigate new operation systems or test the software under different versions of the same operation system. For example, if you need to test the software with Windows 2000/XP/XP SP1/XP SP2/XP SP3/Vista/Vista SP1 it may be quite exhausting to install one system and run test, install another and run test again and so on. Instead you can create images for each operation system and reuse them.

There are only two problems that you should take care of and their names are disk performance and memory sharing.

File system operations are slower, because they are passed through two file system drivers. When the guest operation system writes data to its hard disk, they are saved by Virtual PC somewhere in the big file, which is associated with the guest operation system and called Virtual Disk File. For that Virtual PC uses functions of the host operation system and this causes a performance drawback.

Guest operating system also requires a fixed amount of memory for running. If the processes that you run on the guest operating system require more memory than available, the system starts using swap file and hits file system performance drawback.

So here are a few recommendations for increasing performance of the guest operating system:

• Allocate as much memory as possible for the guest operating system. If you do not start memory consuming applications, you may try to turn off paging file on guest system.
• Prevent fragmentation of the virtual hard disks. Move them to separate partition and defragment it. Ideally, move them to another fast hard disk or RAID.
• Turn off all visual effects and delete all unnecessary files on the guest system hard disk.
• On guest system turn off system restore if you plan to use "Undo disks" option of Virtual PC.

Let’s see how this recommendation can be applied for the virtual machine with Windows Vista Business.

Microsoft Windows Vista requires 512Mb of system memory to be available and 1Gb is recommended for its Business Edition. It means that at least 512Mb of memory should be allocated for the virtual machine and the host machine should have at least 700Mb (~300Mb are required for host operating system). Of course, if you can allocate 3Gb of your 4Gb system memory it is just perfect.

Defragment the volume on which the virtual hard disk resides and create a virtual machine in Virtual PC.

Install Windows Vista and apply the latest service pack. Removing service pack backup files will save about 800Mb on the virtual hard disk. For example, Service Pack 1 backup files can be removed by executing VSP1CLN.EXE command.

Turning off the system restore can save another 1.5Gb on the hard disk.

Turning off visual effects and disabling the Themes service increase user interface performance.

Create another virtual hard disk and move the paging file on this new disk. Configure the system to delete the paging file on shutdown. For this run GPEDIT.MSC, in group policy window navigate to the Computer Configuration/Windows settings/Security settings/Local Policies/Security Options node and enable the Shutdowns; Clear virtual memory page file option.

Install Virtual Machine Additions from "c:\Program Files\Microsoft Virtual PC\Virtual Machine Additions\VMAdditions.iso" (path on host system).

Then defragment the disk of your guest operating system, start the precompactor from "c:\Program Files\Microsoft Virtual PC\Virtual Machine Additions\Virtual Disk Precompactor.iso" (path on host system), turn off the guest system and compact the virtual hard disk image using Virtual PC "Hard Disk Wizard".

Then turn on "Undo disks" and backup the virtual hard disk image.

Now you can test applications, reconfigure the system, experiment and then rollback all the changes without affecting your main working system.