I’m just now getting into the whole VM thing myself. I recently used an application from VMWare known as “VMWare converter”. You can use the software to convert a live production server into a VM without even having to shut it down. I recently created VMs of all of our servers at work, and have been testing them. So far all of them that I’ve tried run perfectly. I just wish the converter app would convert Linux machines. What’s cool is I was able to do all of this with software that VMware just gives away for free. I’d love to see what their higher end stuff does.
Manage, move, swap, backup, restore, failover and replicate all of the VMs in your enterprise from one console. Truly sweeet!
Got five VMs on a physical server and the server dies? No problem, the system will automatically bring them back up in another server in your pool.
I don't have time to go into it tonight but you can do P2V on Linux machines fairly easily.
The short version:
Build a VM using LSI Logic as the driver type for the disk. Don't install an OS, just build the raw disk to be the size of your source disk
On your Source machine ($SOURCE): Boot off a Linux rescue disk and get to a prompt in single user mode with networking enabled. Do the same with your Target machine($TARGET)
On $TARGET enter
time dd if=/dev/sda | nc $TARGET_IP 9999
On $SOURCE, enter
nc -l 9999 | dd of=/dev/sda
You'll have to edit /etc/modprobe.conf, /etc/fstab, /boot/grub.conf, and do a mkinitrd, once the disk image is copied. Freepmail me if you want more information. I just did some testing with this, and am in the process of writing up some documentation.