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Exploiting Virtual PC

Often a single technical user requires multiple machines with differing OS versions, database configurations, network adapters and so on. Usually, we need to setup these machines as separate physical hardware resources.

Virtual PC allows you to run varied combinations of OS, memory, application software and network configurations on a single physical PC. It is like having multiple machines within a single physical machine and base OS.

VPC is a software layer that emulates a complete set of PC hardware – right from BIOS, RAM, Hard Disk, Peripherals, etc. Therefore, you can have a base OS of say Windows XP running VPC software and then boot into a completely separate instance of Windows XP or any other supported operating system (DOS, Windows 95, Windows 2003, OS/2). Further, you can potentially load other operating systems like Linux, FreeBSD, etc.

Virtual PC is now a Microsoft product. It was earlier owned by a company Connectrix, which was acquired by Microsoft.

Once a VPC is configured, it is saved as files. It is then possible to simply copy these files to another physical machine which is running VPC software and then reload the instance of VPC. No setup or configuration activity needs to be repeated.

The need

Now that you know what VPC offers, think of the scenarios when you would find this useful.

Here are some common scenarios.

1. You are a trainer. The training lab in your institute consists of, say, 18 PCs. Depending upon the training topic, you need to reinstall the OS and other products before every training program. With Virtual PC, you need not reinstall the base (host) OS. You can load VPC software on each of the machines, once.

After this is done, all that you need to do is create a VPC image once, as per the training prerequisites, and copy that image onto each machine. That’s it!

Imagine the hours of work and pain it saves every time there is a training on a new topic. You can pre-configure images for your regular training courses. This will also help you in setting labs at customer sites or other locations quickly and accurately.

2. As an administrator, you often have to create a test setup for a new application. This typically involves having spare hardware of correct configuration. Often this is not available.

Using VPC it is extremely easy to setup the new application on an existing hardware without disturbing the host machine. This way, you can load the VPC and test the application on demand.

3. Compatibility testing is a mandatory if you create packaged products. You need to test your software on various combinations of OS versions, service pack levels, database driver versions, display resolutions and so on. This is a daunting task because you need to have a large number of physical machines to handle the sheer number of configuration combinations. Using VPC you can dramatically simplify this process. All that you need to do is to create a VPC for each configuration combination once. Later you can use a VPC to test your software. Later you can restore the base configuration (for another round of testing) by undoing the application level changes. This is called ‘undo disk’ feature.

4. When you want to show a demo or pilot of a software which has client and server component, you must have two networked machines.

Using VPC you can have the server and client (or multiple server) components in two separate VPC images or you can use host machine to act like server or client. This eliminates the need for having two physical machines and simplifies the pain involved in delivering live presentations for complex products.

I am sure that, based upon these scenarios, you have got enough ideas of when to use VPC.

Availability

This product is available from Microsoft. The evaluation edition can be downloaded from the website. MSDN Universal Subscribers get a VPC edition by default.

Although you can load any x86 operating system on VPC, it still requires the base license for host as well as each VPC OS from the related vendor.

VPC requirements

• Hardware:

VPC stores the entire configuration as simple file system files. Therefore, each file tends to be huge in size (multiple GBs). The exact size will depend upon the OS and the additional applications loaded. Therefore, you need substantial amount of hard disk space. Nowadays, 80 GB HDDs are available below Rs 5000. So it is not a problem at all.

In order to manage multiple instances of operating systems and applications efficiently, the RAM requirements are also high. Each VPC can be configured to use a limited amount of RAM. Still, it is a good idea to have a substantial amount of RAM for effectively using VPC.

As VPC emulates the entire hardware setup for an instance, a fast processor is also a must. Base Hardware prerequisites are given below.

• An x86-based computer with a 400 MHz or faster (1 GHz recommended) processor with L2 cache. Virtual PC supports the use of AMD Athlon/Duron, Intel Celeron, Intel Pentium II, Intel Pentium III, and Intel Pentium 4 processors. Virtual PC also can use AMD Opteron processors, but only with 32-bit host operating systems. You can run Virtual PC on a multi-processor computer, but it utilizes one processor only.
• CD-ROM or DVD drive
• Super VGA (800 × 600) or higher resolution monitor recommended
• Keyboard and Microsoft mouse or compatible pointing device
• 512 MB or more RAM (practically)
• Software:

Although VPC supports many Operating systems right from DOS, the VPC software itself requires Windows XP or Windows 2000 and above.

• RAM and disk space:

Here is an indicative chart of memory and disk space requirements for various OS versions hosted under VPC. Please note that these requirements will increase as you load more application software on top of the VPC OS.

Using VPC

This section assumes that you have loaded the base VPC software.

• VPC Console

The entire lifecycle of creating and managing VPC images is handled from the console.

When you click New… a wizard starts. In this wizard you need to choose the guest operating system. There is an option called “Other” which provides the facility to load any other x86 OS. You need to have the CDs for the guest operating system to continue with further installation.

In the next step, you can decide how much base RAM will be available to the virtual machine. You can increase the default value, if you have enough RAM on the host machine.

After completing all the wizard steps a new VPC will be created. The file name is .VHD.

Now you can choose this instance and click on Start button. As we have just created this base instance, it is like an unformatted machine with no OS on it.

When you start a fresh VPC instance, it boots as though a normal bare PC boots!

Now you need the Operating System CD. You need to proceed and setup the OS as though you were loading it on a new PC. Once you have finished loading the software, you can save the VPC and reuse it later.

Depending upon your requirements you can also load additional software and configuration settings.

Special keys

As VPC behaves like a PC within a PC, you may get confused with keyboard and mouse handling. In particular, the system keystrokes work within the VPC. For example, if you press Alt+Tab, it will shuffle applications within the VPC. Further, once the mouse point enters the VPC screen, it gets bounded by the VPC window. This is called ‘Mouse Capture’.

To move mouse context from a VPC to host PC, you need to use the so called “Host Key”. This key is the Right-Alter key by default. However, it can be configured by you. Pressing and releasing the host key alone, immediately nullifies the mouse capture and gives mouse control back to the host operating system.

In addition, you can press the Host Key along with other keys to perform many other useful tasks.

More usage

This was just the beginning of VPC usage. Next week we will explore more in-depth usage of

VPC.

About the Author:Dr Nitin Paranjape is the Chairman and MD of Maestros (Mediline). He is a consultant with many organisations, covering appropriate technology utilisation, business application of relevant technology, application architecture and audit as well as knowledge transfer. He has authored more than 650 articles on various technology-related subjects. He can be contacted at nitin@mediline.co.in