Q: How to run Boot Camp on External Hard Drive?

Zathrak wrote:

 

On a peripheral note, I'd also not be too keen on running my Windows partition via USB 3.0 even if it were possible simply due to bandwidth. I'd rather use Thunderbolt, again...if it were supported.

USB3 connections are faster than most internal connections, there no performance issues except Windows reluctance to run from an external drive.

Oh come on... even on USB 2 it's worth it !

The only point of installing Windows on a external drive is because you may need windows from times to times, but you don't want to loose some precious disk space over something you barely use...

so installing Windows on an external drive (even if that's a slow USB 2 Hard drive or even USB Key), is a good way to test Windows software when needed. and beyond slowness, that's the only issue you'll encounter, and you know it in advance : your external windows won't be as fast as if it were installed onto the bootcamp partition on your internal SSD drive... deal with it !

And did I mention that you can this way use the same external Hard drive on several Macs ?

you can use the same Windows on an iMac and a MacBook pro for instance, Windows will add needed drivers, maybe you'll have to reinstall the Apple bootcamp drivers when plugged to another computer, but that's it !!

there's not any downside on doing this !

you can buy a SSD thunderbolt powered drive, yes, you can, but that's up to you and your budget !

To @ Fuberman

I made this guide for Windows 8.1, you should try it with the windows 8.1 test drive ISO available on the Windows website.

you can also give me the BSOD error message you got when booting windows.

maybe it's just nothing.

but just to be sure, try installing windows 8.1 please !

@Pierre80

Thanks for trying helping me out on this one.

I would like to try with Windows 8.1 I'm just not sure if it's possible for me to

use Win8.1 though i'm only have a license key for Win7.

But i will try it out the next couple of days, when the time allows me

I have just updated to Yosemite, i do not hope that make any difference...

/Pierre

Try this..

http://twocanoes.com/winclone/support/migrate-windows-8-to-an-external-drive-usi ng-winclone-4.3-and-later

It took me 15min to move bootcamp to USB drive and it boots to an external drive now...Just buy winclone for 29$ and save yourself a headache..instruction is on their site and 3 easy step..

1. Plugin external drive and partition it MS-DOS(Fat32)

2. Select Bootcamp partition in Disk utility and migrate bootcamp to external..

3. Reboot by pressing "option" and select external..

Finally , reclaim your extra space anf make your MacintoshHD a single drive again

Now i've had the time to try Pierre80' user guide again with Win8.1 and i guess i took me around 30 - 45 min and then everything

works smooth, rebooting from external USB3 disk, and no Windows installed to the Mac

And best of all...it's for free

So i can only recommend this guide, just be aware, Windows have to be 8.1.

✌️ I'm glad that my guide worked for you, and you're right, it's free

feel free to mark my guide as a solution or grant me points  

hi am a newbie here ... can i know the total size needed for installation on the USB 3 drive? intend to try pierre80's guide because i do not want to waste precious space on something i will only use rarely. tq

Mac OS Yosemite and Win8.1 on external Thunderbolt/USB 3 drive.

How to:

Remember before you start: Make sure you have updated backups on everything involved, unmount all not necessary drives. during the different stages unmount the drive not working on i.e. if you are doing things on the  external unmount the internal. Take your time and be sure to choose the right drive and partition so you don’t mess everything up.

1. Update all Mac OS updates from Mac App Store.

2. Run Boot Camp on internal (original) drive, including make a USB stick drivers for Win (Can take forever on a slow USB stick, but will get there) Install Windows from DVD or similar (I did from a bought DVD, no OEM allowed)

3. Test-run and configure and add all updates for Windows and installing an Antivirus app is also good to do.

4. Install a new fresh Mac OS on an external USB or Thunderbolt drive (or use CarbonCopyCloner to get a copy of internal Mac OS)

5. Check the new external Mac OS by rebooting to it. if Ok, reboot to internal again.

6. Run WinClone 4 and make an image file from the Boot Camp to an image file to your desktop.

7. Run Disk Utility and select your external drive, Choose the Partition tab, click the + below the main (only partition), select the space between the now two partitions and drag upp or down until lower parts size is at least a tad bigger than the original Boot Camp volume or bigger. Select the new partition and rename it and choose to format it to MS-DOS FAT. Execute.

8. Run WinClone again and choose your new image-file, and target your new FAT-partition on the external drive.

9. Reboot the Mac, and when screen goes black, press and hold the alt-button until the startup drives is shown, select the new Windows disk on your external drive. If all ok your computer will start on Windows on your external drive. When running Windows goto your USB-stick open the Boot Camp folder and run the setup.exe.

When all seems to work ok reboot again and this time to your internal Mac OS.

10. When in your internal Mac OS, run the Boot Camp app again and make sure only the Remove Win8xx is checked, run and the Boot Camp will be removed on your Mac drive.

Check-run everything agan.

Thats how I did it, might be easier way but at least I’m a happy camper now :-)

So now I have the options to run Mac OS on my internal drive, run Mac OS on my external together with Parallels Desktop and Windows 8.1 in a virtual or just run Windows only on the external drive (best for gaming etc in windows)

Hi, I'm trying to run windows off of an external hard drive because I ran out of space on my internal and can't delete stuff (I need it all).

I followed your directions using a boot camp created install USB stick as my iso source. Everything worked, except that I had to type 'create partition primary' at step 8 instead of 'create partition 1'. After I finished all of the setup, I went to boot up my MacBook Pro from the external hard drive, but I got the "boot files are missing or corrupted" error message (not exact quote; for obvious reasons I don't have a screen shot). When this happens to "actual" windows users, they load in the install source and boot from that, then click repair. I did that, but it only gave me the option to install windows on my various partitions; as far as Setup was concerned, there was no windows install to fix. I then plugged the hard drive back into the windows machine and did the boot files transfer again, but I got the same results. Your directions expected windows to simply reboot after the first time, but it never tried that. What is going on?

Hardware: 2014 MacBook Pro Retina, i7 chip

WD Elements 1 TB 7200 RPM external HD (USB 3.0)

This is not helpful nor does it actually answer the OP's question, as this assumes you already have Windows installed. The point of this thread is to install Windows on an external drive through Boot Camp, not copy an existing Boot Camp partition (which is fairly simple to do). The answer is already further up the thread: installing to an external drive is only possible over Thunderbolt. This makes sense because TB is simply an extension of the PCIe interface.

Forget it, didn't see who you answered at först.

✌️ I'm glad that my guide worked for some of you. If it didn't, it's because you surely didn't follow it thoroughly.

@GGooeytoe

Maybe you should use the .iso instead of the USB drive made from the .iso. That does not change anything, you're right, but you never know, maybe it does. Anyway, maybe you should try to start over.

@AirGoggles

You can't install windows 8.1 to a USB drive, whether there is a Mac involved OR EVEN A REAL PC. You just can't! The Windows 8 installer prevents this kind of installation (not sure about previous Windows, but I'm pretty sure that's the same).

You're sure that Windows 8.1 installer considers a Thunderbolt drive as an Internal drive like a SATA drive ?

I don't own a Thunderbolt drive. nor does 95 % of the regular Mac users.

Nowhere did I say anything about Windows 8 so why are you asking me? From the experience that others here have pointed out, it works.

The issue with the Thunderbolt drive isn't a Windows issue; it's a Boot Camp issue. Boot Camp simply doesn't give you the option to install Windows on an external drive. Thunderbolt drives seem to be the exception, likely because they are an external extension of the PCIe interface (an internal connection). I've installed Windows XP on a USB hard drive through Boot Camp before, so this is a change within the last couple years.

I haven't tried that and it might make the difference, but I found an "easier" way:

Use a free tool called Win2Go. I think it probably does exactly what you described, but it does it for you. Guide follows.

What you need: a .iso or .img of windows 8.1 (should work with other versions, but this guide won't be quite right)

a windows install usb stick you created with boot camp (make sure you had the second option, "Download drivers," checked. The drivers are what we care about.)

A windows machine with administrator privileges and (preferably) USB 3.0 ports

a Macintosh computer (duh! :D)

1. Get a .iso of Windows 8.1 (it can also do earlier versions, but this is the one I know). If you have a .img like I did, simply rename it as a .iso. DO NOT have your bootcamp usb stick plugged in during this entire process. It gets very confused and tries to install windows to your internal drive around step 10 if you do.
2. Partition the drive you intend to install windows on. I did this using MacOS's Disk Utility because I knew how. Anyway, make at least one partition on the drive named "WINDOWS" with at least 20 GB of space (could use less, but if you want to be able to do anything later, more is better.) The format of the partition is unimportant at this point.
3. Get access to a windows device as an administrator. I used a bootcamped macmini running windows 7.
4. Put the windows .iso from step 1 somewhere the windows account from step 3 can see it (i.e. on a flashdrive).
5. Download Win2USB from http://www.easyuefi.com/wintousb/ and install it. You can do steps 6 and 7 while this is occurring, but it should be pretty fast.
6. Plug the drive into your windows device, preferably via a USB 3.0 port.
7. Right click on the "WINDOWS" volume that should appear in windows explorer. Choose "format" and format the partition to MS-DOS.
8. Start up Win2USB and work through the wizard:
   1. Choose the .iso from steps 1 and 4 as your source.
   2. Make the WINDOWS partition both the system and boot partition (you could get fancy and make two, but I didn't bother).
   3. Let it run. This will take some time; try not to do anything on the computer while it is installing. I maxed out my internal drive's read/write speed during this process.
9. Once it is done, EJECT the harddrive (windows may refuse to do this; if so, simply turn the computer off before removing it).
10. Plug the drive into your mac and hold down OPTION while it starts up. You should see a screen with all of your partitions shown, plus one (or possibly two) orange things named windows. Use the arrow keys to pick either of the windows choices (they are actually the same thing as far as I can tell) and hit enter.
11. It should boot into windows and take a LOONG time, then shut down. Do step 10 again and it should boot fully, as well as asking for your product key.
12. Make sure it takes your product key and boots fully. Things may look weird and you probably won't have internet access; the next steps fix this.
13. Boot your new windows partition and then insert the bootcamp flashdrive (NOT the other way round).
14. Navigate to the folder on the flashdrive called BootCamp and run setup.exe. It will install the drivers you need to make your apple wifi chips, graphics stuff, keyboards, etc work properly. The screen will probably do strange things during this process and especially as it is finishing. Don't panic.
15. Reboot, possibly more than once. Basically, you just keep rebooting until it stops doing weird stuff. It took me two cycles.
16. Everything should work at this point. If not, I forgot something.