OS X on external Drive and Boot Camp

Nunyabinez · Dec 17, 2014

I was hoping someone would help me with a question. I have been trying to figure out a way to get Windows onto an external drive and have not succeeded.

Apparently, it is possible with a thunderbolt drive because it is seen a an extension of the internal bus, but I have UBS 3.0 drives and don't want to spend what it costs for a thunderbolt drive.

Here is my question: Does anyone know if I could install OS X on an external USB 3.0 drive and then use the boot camp assistant to install windows on that drive? That way I could use all of my internal SSD for my Mac and then boot into OS X on the external drive and use the startup drive tool to boot into Windows. I know that's a cludgy way to do it, but I wanted to know if anyone has successfully done this successfully before I move data around and reformat drives, etc. Any ideas? Thanks guys.

sonicrobby · Dec 17, 2014

I'm not sure you'd even need to install OS X onto that external, you should be able to install windows directly onto that drive. I've never actually done it directly from a Mac, but I have done it on windows.

Worst case scenario, use boot camp to put windows on your ssd, then though windows, try installing windows on the external. Make sure the external is formatted for windows tho. In the past I haven't had issues with this. When windows install prompts for the drive, simply select the external and it should go through the motions.

Nunyabinez · Dec 17, 2014

sonicrobby said:
I'm not sure you'd even need to install OS X onto that external, you should be able to install windows directly onto that drive. I've never actually done it directly from a Mac, but I have done it on windows.

Worst case scenario, use boot camp to put windows on your ssd, then though windows, try installing windows on the external. Make sure the external is formatted for windows tho. In the past I haven't had issues with this. When windows install prompts for the drive, simply select the external and it should go through the motions.

Unfortunately, Windows does not support installing to external disks. Even if you create a USB thumb drive installer, it can tell what is internal and what is external. I tried using Macrium Reflect which creates bootable clones of Windows disks, but the Mac won't recognize the disk when I use the option key at boot up.

sonicrobby · Dec 17, 2014

Nunyabinez said:
Unfortunately, Windows does not support installing to external disks. Even if you create a USB thumb drive installer, it can tell what is internal and what is external. I tried using Macrium Reflect which creates bootable clones of Windows disks, but the Mac won't recognize the disk when I use the option key at boot up.

Well that's a shame. Actually now that you mention it, I do recall putting the external hxD inside my tower computer, installing windows onto it, and then putting it back into its external case. Any friends of yours have a tower of you can use to attempt that?

Nunyabinez · Dec 17, 2014

sonicrobby said:
Well that's a shame. Actually now that you mention it, I do recall putting the external hxD inside my tower computer, installing windows onto it, and then putting it back into its external case. Any friends of yours have a tower of you can use to attempt that?

Unfortunately not. I do have a toshiba external drive formatted with NTFS that is recognized in the option boot. I may try cloning my boot camp to that and seeing if it will launch. If not, I'll try my original idea of putting OS X on an external drive and seeing if the boot camp assistant will recognize it as internal.

hfg · Dec 17, 2014

Search around here and you will find several methods for putting Windows on an external disk ... including "Windows To Go" methods.

However, I find the easiest for me is to use BootCamp to install a local internal Windows and get it stable. Then, use "WinClone" to take that image and put it on a external drive (I usually use either LaCie "Rugged" Thunderbolt or Seagate Thunderbolt adapters) ...then use BootCamp to remove the internal install and return the space to OS X. You can then use WinClone to maintain periodic backups of your Windows installation.

I have done it many times and "WinClone" by TwoCanoes Software has never let me down.

yjchua95 · Dec 17, 2014

Nunyabinez said:
I was hoping someone would help me with a question. I have been trying to figure out a way to get Windows onto an external drive and have not succeeded.

Apparently, it is possible with a thunderbolt drive because it is seen a an extension of the internal bus, but I have UBS 3.0 drives and don't want to spend what it costs for a thunderbolt drive.

Here is my question: Does anyone know if I could install OS X on an external USB 3.0 drive and then use the boot camp assistant to install windows on that drive? That way I could use all of my internal SSD for my Mac and then boot into OS X on the external drive and use the startup drive tool to boot into Windows. I know that's a cludgy way to do it, but I wanted to know if anyone has successfully done this successfully before I move data around and reformat drives, etc. Any ideas? Thanks guys.

This method works for both USB and Thunderbolt, booting in UEFI:

Connect external drive to Windows VM. You must have a Windows VM in VMware/Parallels.

What you need:
install.wim file (obtain this from your Windows ISO)

Open elevated cmd.exe

Note: All commands aren't case sensitive, including pathway to files.

Type diskpart
Type list disk
Take note of the disk you want to select
Type select disk 1 (if your disk is Disk 1)
Type clean
Type convert gpt
Type create partition EFI size=100
Type format quick fs=fat32 label=EFI
Type assign letter=S
Type create partition primary
Type format fs=ntfs quick label=W2G (or any other name you wish for label)
Type assign letter=E
Type exit

Open up File Explorer. In your C drive, create a new folder named WIN2GO.
Put the install.wim file in this folder

Back in cmd.exe:
Type dism /apply-image /imagefile:C:\WIN2GO\install.wim /index:1 /applydir:E:\ (this process will take quite a while)
Type E:\Windows\System32\bcdboot E:\Windows /s S: /f UEFI

Restart your entire Mac. After the chime, hold down Option and when prompted to select your boot drive, select EFI Boot.

Proceed installation normally.

After installation, install Boot Camp drivers.

No need to pay for WinClone or create an internal Boot Camp partition. A VM will do (can be VirtualBox or a trial of Parallels or VMware).

This method basically takes advantage of the dism.exe utility to create an unofficial Windows to Go drive.

Please PM me if you run into any difficulties, I'll be happy to help.

Nunyabinez · Dec 17, 2014

yjchua95 said:
This method works for both USB and Thunderbolt, booting in UEFI:

Connect external drive to Windows VM. You must have a Windows VM in VMware/Parallels.

What you need:
install.wim file (obtain this from your Windows ISO)

Open elevated cmd.exe

Note: All commands aren't case sensitive, including pathway to files.

Type diskpart
Type list disk
Take note of the disk you want to select
Type select disk 1 (if your disk is Disk 1)
Type clean
Type convert gpt
Type create partition EFI size=100
Type format quick fs=fat32 label=EFI
Type assign letter=S
Type create partition primary
Type format fs=ntfs quick label=W2G (or any other name you wish for label)
Type assign letter=E
Type exit

Open up File Explorer. In your C drive, create a new folder named WIN2GO.
Put the install.wim file in this folder

Back in cmd.exe:
Type dism /apply-image /imagefile:C:\WIN2GO\install.wim /index:1 /applydir:E:\ (this process will take quite a while)
Type E:\Windows\System32\bcdboot E:\Windows /s S: /f UEFI

Restart your entire Mac. After the chime, hold down Option and when prompted to select your boot drive, select EFI Boot.

Proceed installation normally.

After installation, install Boot Camp drivers.

No need to pay for WinClone or create an internal Boot Camp partition. A VM will do (can be VirtualBox or a trial of Parallels or VMware).

This method basically takes advantage of the dism.exe utility to create an unofficial Windows to Go drive.

Please PM me if you run into any difficulties, I'll be happy to help.

Thanks for the guide. I will give it a shot and let you know how it goes. I already have windows 10 TP in parallels.

SaSaSushi · Dec 17, 2014

hfg said:
I have done it many times and "WinClone" by TwoCanoes Software has never let me down.

Absolutely excellent advice. WinClone is the easiest, most intuitive and fastest method of moving, backing up and/or replicating BootCamp.

No kludges, no convoluted hacks and no nonsense. It's well worth its price.

steve62388 · Dec 17, 2014

SaSaSushi said:
Absolutely excellent advice. WinClone is the easiest, most intuitive and fastest method of moving, backing up and/or replicating BootCamp.

No kludges, no convoluted hacks and no nonsense. It's well worth its price.

Except it doesn't always work.

OP, also see my post here https://forums.macrumors.com/threads/1818859/

SaSaSushi · Dec 17, 2014

steve23094 said:
Except it doesn't always work.

OP, also see my post here https://forums.macrumors.com/threads/1818859/

And, as pointed out to you in that thread, this was most likely not due to any limitation whatsoever on the part of WinClone but rather an issue with the enclosure you were using.

espnfanco · Dec 18, 2014

A couple nights ago, I was able to install Windows 8 on a Lacie TB external SSD drive just using bootcamp. I have read there might be compatibility issues with USB 3.0.

steve62388 · Dec 18, 2014

SaSaSushi said:
And, as pointed out to you in that thread, this was most likely not due to any limitation whatsoever on the part of WinClone but rather an issue with the enclosure you were using.

And just like the makers of Winclone you neglect to mention that it doesn't always work. Are you employed by them?

SaSaSushi · Dec 18, 2014

steve23094 said:
And just like the makers of Winclone you neglect to mention that it doesn't always work. Are you employed by them?

I have no connection to TwoCanoes Software other than being a very satisfied customer.

Yes, Windows does not work on all external devices. Sorry to hear about your issues, really, but the developers of WinClone can not be held responsible for hardware incompatibilities, no matter how much want to blame them for it.

Nunyabinez · Dec 18, 2014

So, using yjchua95's method I was able to get everything working. One issue I had was that several of my drives would just not appear in the option menu no matter what I tried. I have a fairly new toshiba canvio drive and since it would consistently show in the option menu I put windows on that.

I will likely experiment more as I have an SSD that I would rather use, but I may need a different case for it to work, or I may just be stuck with the toshiba, which is OK.

So, thanks yjchua95.

yjchua95 · Dec 18, 2014

Nunyabinez said:
So, using yjchua95's method I was able to get everything working. One issue I had was that several of my drives would just not appear in the option menu no matter what I tried. I have a fairly new toshiba canvio drive and since it would consistently show in the option menu I put windows on that.

I will likely experiment more as I have an SSD that I would rather use, but I may need a different case for it to work, or I may just be stuck with the toshiba, which is OK.

So, thanks yjchua95.

Glad it helped.

For the record, you need to purchase enclosures that support UASP.

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