Invirus sent me a note about a product they have to opimize virtual machine images. Finally got around to trying out the product and it’s pretty slick. It basically rips through your VMs and shrink them down without affecting the OS inside of them. VM Optimizer 2.0 will work with files from both VMWare and Virtual PC/Virtual Server vhd files (although in my test I tried shrinking an identical file of both types and for whatever reason, the Virtual PC file showed better compression).
What was useful for me was that I had a large (7GB) VM that I wanted to move to another external drive that was FAT16 formatted (most USB drives are so they’re compatible with Macs and Windoze). The external drive in this format doesn’t support individual files larger than 4GB so this was a problem. Not anymore. I ran the optimizer and it shrunk it down to 3.3GB and was able to transfer it. The reduced size also decreased the load time of the VM by a bit, so there’s some savings there if you’re starting and stopping these things all the time.
There’s a 30 day trial available which is a full version so you can try out all the features and see if it works for you. Check it out as it’s a cool product and doesn’t seem to have any adverse effects on VMs, other than making them smaller. And remember, size matters.