As an avid proponent of virtual machines (e.g. Microsoft Virtual PC, VMWare, Virtual Server, etc), they play an integral part in my role as a software developer.  While I haven't yet made the switch over to have my primary development environment (which I may do at some point), I find them to be extremely useful especially for testing software or hosting services that I would not otherwise want to install locally.

A virtual machine does tend to get quite large.  I have several virtual machines where the VHD (virtual hard drive) file exceeds 10 GB.  Zipping a 10 GB file takes quite a while.  If I want to burn it to DVD, for example, I have to spend a while zipping it and copying it.  Extracting seems to take even longer and it's a lot of time that I don't really have.

Several months ago I had evaluated a product by Invirtus called the Invirtus VM Optimizer.  While I don't like their evaluation scheme (which only allows for one usage per VPC - and it's easy to do it wrong if you're evaluating the software, rendering it virtually useless), there are many raving reviews online about the product.  We recently purchased the Corporate Edition v2.5 and I took the time today (being that it's a weekend) to 'optimize' my set of clean images.

To expedite the process of building a new VPC I've assembled a collection of 'clean' images.  A clean image in this case has no additional software installed on it except the base OS and hotfixes.  I will periodically dip into the archive, open each VPC and update it to the latest of all hotfixes and patches and then rearchive it with the appropriate date stamp.  I optimized 5 VPCs today and achived an average size reduction on the VHD files of 58.7% (not bad at all).  :)

Now I can put all five back onto a single DL DVD without the need of zipping/rarring them up which makes the whole proposition even more exciting.  Here are my results:

Windows XP SP2:

5,113,091 KB before
1,362,287 KB after
73.36 % savings

Windows 2000 Professional:

2,757,316 KB before
1,163,583 KB after
57.80 % savings

Windows 2000 Server:

2,757,316 KB before
1,268,056 KB after
54.01 % savings

Windows Server 2003:

3,199,792 KB before
1,352,045 KB after
57.75 % savings

Windows Server 2003 + CRM 3.0/SQL Server/etc:

4,248,624 KB before
2,329,179 KB after
45.18 % savings

Total:

18,076,139 KB before
7,475,150 KB after
58.65 % savings