Virtual machines on USB external disk

Question

I'm thinking about installing (using Sun Virtual Box) Ubuntu 10.04 and Windows 7 on an external disk connected to the USB port of my new MacBook.

Do you think perfomances will be terrific? Have you tried something similar?

Answer 1

You definitely either want to have the VM image on the internal disk or on a very fast external connection such as eSATA or FW800. USB2 is just going to be painfully slow.

Answer 2

The performance will definitely suffer. I tried this recently and it crawled for me.
First off your HD is the slowest bottleneck in most systems which are heavily disk intensive.
Second you are using USB 2.0 which is slower than a normal HD connection which has a direct route.
Lastly if your external drive loses it's connection your VM could have significant damage.