Virtual PC - Beyond the Basics

Published 27 April 05 07:24 PM | russnem

With the help of the Virtual PC Master Brian Randell and my good pal Ken Getz I have learned about the beauty of what are called "Differencing Drives". Differencing Drives allow you to create a VPC with an operating system (in my case Windows Server 2003, activated, with the Virtual Machine Additions) and then use that as a starting point to branch out and install various other things without having to touch the core operating system installation.

I was able to create a great heirarchy of installations that will help me over the next several months. I created a differencing drive for a SQL Server 2000 installation that was based on the OS main virtual hard drive. I also created a differencing drive for SQL Server 2005 based on the same core OS hard drive. In addition, I created a differencing drive based on the SQL Server 2000 differencing drive to install Whidbey Beta 2.

The beauty of this set up is that I can still base other differencing drives on the same SQL Server 2000 differencing drive (which is, in turn, based off that original Windows Server 2003 hard drive) and save all the space that would normally be needed for the operating system and SQL Server, such as an installation of later Whidbey bits, Visual Studio 2003, or any other software that might be required. No matter what, I have a fresh, clean Windows Server 2003 installation that is activated and a fresh and clean SQL Server installation with SP3a applied.

When you depend on Virtual PC as much as we do for demos and talks at the various conferences we speak at or to play with beta software, it is important that you have the ability to burn these things to DVDs in case of emergency. That way, if your laptop dies or gets stolen you can simply copy the VPCs to a friend's laptop and you're up and running and you can do your sessions as if nothing ever happened.

Thanks to Brian and Ken for the guidance!


# bob said on April 28, 2005 12:10 PM:

Just remember, once you base a new drive off an existing one, you can never again boot into or change the existing one.

So, base W2K3, installed and activated.

SQL2K, based off of W2K3.

Now another new one based off of SQL2K to do demos with, or one to add whidbey bits, or whatever.

You can only ever boot up the last one in the chain. If you boot any of the ones that are "depended" on, you lose any of the ones later in the chain.

This stuff does have uses, great uses, just be sure to not boot up the wrong one.

A great way to be sure is to make the base drives be the transactional type, so if you boot one accidentally, you can abandon all changes at shutdown.