I'm looking to do away with my Boot Camp partition. Now I've bought a 2 TB external drive, and I was wondering if it's possible to either install a Boot Camp partition onto the external drive, or failing that, how much of a performance drop I'll see if I install a VM via Parallels Desktop onto the external drive.
It's a USB 3 external drive.
My Mac is a MacBook Pro late '13, 2.4 GHz Intel i5, 8 GB of DDR3 RAM
Best Answer
It seems to be possible to install Windows 7/8 to an external drive but a lot of work is necessary to overcome Boot Camp/Windows 7/8 restrictions.
The following guide is shamelessly stolen at bleeptobleep.blogspot.de. All credits go to the the respective persons/groups of persons.
To keep the formatting and improve readability i didn't choose the quote tags.
Mac: Install Windows 7 or 8 on an external USB3 or Thunderbolt drive without using bootcamp
Introduction
After I received my new iMac with a 3 TB Fusion Drive, I was disappointed when I realized that Bootcamp was not running on this model and prevented me from installing Windows on it. I wanted to take advantage of the powerful iMac hardware to play games but I couldn't.
There are a few ways of working around this limitation, but I found most of them quite complex and most of the time they required formatting the internal hard drive or repartitioning it and go for a brand new installation of Mac OS X. I was not comfortable with that.
But there is another way, and that is to install Windows on an external hard drive, using either USB or Thunderbolt. Personally I used a Lacie Rugged 1 TB drive that has both USB3 and Thunderbolt connectors. Both work very well.
This guide may interest you if:
What this guide will make you do:
What this will not make you do:
What you'll need
IMPORTANT: If your Mac has a 64 bits processor, your Windows Virtual Machine on OSX, your Windows installation on your PC and your Windows DVD/ISO must also be in 64 bits!
Step by Step guide
Step 1: Get the install.wim file
If you have a Windows ISO file:
Mount the ISO
Open the mounted drive, then go to the "sources" folder and locate the "install.wim" file. Save this file to C:\wim\ on your Windows installation or virtual machine.
If you have a Windows DVD: open the "sources" folder on the DVD and locate the "install.wim" file. Save this file to C:\wim\ on your Windows installation or virtual machine.
IMPORTANT: If instead of a "install.wim" file, you have "install.esd", you can not continue this step by step guide. And an ESD file can not be converted into a WIM file. So you must get a version of the Windows installation DVD/ISO that has an install.wim file.
Step 2: Clean, partition and format your external hard drive
diskpart
list disk
This will display a list of disks mounted on your computer or virtual machine. Make sure your drive is listed here before you continue.
select disk #
clean
convert mbr
create partition primary size=350
This will create a 350MB partition on your external driveformat fs=fat32 quick
active
assign letter=b
Windows will detect a new drive and probably display a pop-up. Ignore that.create partition primary
format fs=ntfs quick
assign letter=o
Windows will detect a new drive and probably display a pop-up. Ignore that.
exit
Step 3: Deploy the Windows installation image
imagex.exe /info C:\wim\install.wim
imagex.exe /apply C:\wim\install.wim 1 o:
This will take some time. The Windows installation image is being deployed to your external driveo:\windows\system32\bcdboot o:\windows /f ALL /s b:
Step 4: Boot from your external drive and install Windows
Plug in your external drive:
Reboot your Mac and once the bootup sound is over, immediately press the ALT (option) key and release it only when the boot drives selection screen appears. If you did not get the boot drives selection screen, reboot and try again. The timing to press the ALT (option) key is quite short. It must not be too early or too late.
Step 5: Install bootcamp drivers
Credits, sources and big thank you to:
tweaks.com where I got the info on how to install Windows to go on a USB external drive
Chris F Caroll where I finally found where to download the bootcamp drivers without running bootcamp
Macrumors forums for the very helpful forum members
To answer your second question about performance drop:
I don't have a Boot Camp partition so i can't compare Windows Boot Camp to a Windows VM.
But i may give you a Mac <-> Mac VM comparison and single Windows 7/8 VM benchmarks:
Geekbench 3 Benchmark:
Windows Experience Index:
Windows 7 Parallels VM, 2 (virtual) cores, 4 GB (WEI: 1.0-7.9):
Windows 8.1 Parallels VM, 2 (virtual) cores, 8 GB (WEI: 1.0-9.9):