Resolved rMBP, Bootcamp off thunderbolt drive - MORE COMPLETE SOLUTION

[yjchua95]

So I finally got around to trying this method but couldn't get it to work. I get to the stage where I need to boot from the EFI partition on the thunderbolt drive, but my computer just hangs when I select the EFI drive on the option+boot screen. For what it's worth, I accessed cmd through bootcamp using the Windows 10 technical preview (Virtualbox wouldn't see the thunderbolt drive).

Here's the partition layout as seen by disk utility in OS X:

Follow my instructions (it's in the post right above yours).

 

[El Jengibre]

I did, but unfortunately something isn't working.

On my MBP, the computer freezes when I select the EFI drive from the boot screen (holding option down while restarting).

My retina iMac shipped last night. When I try to boot the thunderbolt drive from there, the screen just goes black.

Both computers are able to see the EFI partition, but can't actually boot into it.

 

[yjchua95]

I did, but unfortunately something isn't working.

On my MBP, the computer freezes when I select the EFI drive from the boot screen (holding option down while restarting).

My retina iMac shipped last night. When I try to boot the thunderbolt drive from there, the screen just goes black.

Both computers are able to see the EFI partition, but can't actually boot into it.

For Thunderbolt drives, you can actually just start up from a USB Windows installer and install it to the TB drive directly, because Windows sees the TB drive as an internal PCIe connection. No need to mess around with the command line, with the exception of turning it into GPT first.

 

[bergui45]

I have tried what yjchua95 recommends:
I have Booted from Bootcamp internal drive: everything went flawlessly but
unfortunately:
Type dism /apply-image /imagefile:C:\WIN2GO\install.wim /index:1 /applydir:E:\ (this process will take quite a while)

this is not blessed!
Option apply-image/imagefile is unknown?

Let me know how to have success with this Cmd.line (run as admin)

 

[Cloudane]

I use a different technique now, but the bad news is it requires the purchase of some $40 software. My notes say thus:

It is now simple (but must still be a hybrid on the target drive)
Have more than 20GB free on the system drive, and use Boot Camp to install internally as normal. Install the Boot Camp drivers etc.

Now use WinClone to shift it to the external drive (make sure it's GPT, partition as desired, use MSDOS format, then use WinClone to move the Bootcamp across)

That's it! Re-run Bootcamp to delete the internal partition.

If it doesn't boot and ends with a sad face, which seems to happen with Windows 8, after a few tries it'll offer safe mode. Try that. Or try winclone's “make MBR bootable” and try again including the safe mode.

There doesn't seem to be anything we can do about it needing to be hybrid and booting from the emulated BIOS. I have spent days trying. Newer Macs might, but mine will get stuck on the boot screen if a purely GPT/EFI based Thunderbolt is even plugged in. At least we no longer need an internal partition.

 

[bergui45]

Hello Cloudane,

do you have a mid 2012 MBPro 15" like mine?
i finally get success thanx to yjchua95's recipe without using a VM but the internal Bootcamp Windows10.
I skipped the last cmd lines: "dism/apply-image... and EFI_Booted from my USB stick after disconnecting all my internal disk. The Windows installer blessed the hard disk inside the Thunderbolt bay!
But i 'm not sure it's rock stable since i suffer a lot of restarts (windows update?...)
So i'm waiting a couple of more days before scavenging the internal Bootcamp partition...

 

[Cloudane]

Mine's a 2011 Macbook Air 11". All I can say is the way I settled on has it working flawlessly

 

[vhp3]

I did exactly as the above instructions, and held option and was able to boot into windows 10. When I reboot this morning into OS X and try to select the startup disk with no avail. I get the bless tool error.

I have done this with win 8 on my mac pro so I am not new at this. Still trying to work it out. it seems to be a lot of
trial and error.

 

[vhp3]

I did exactly as the above instructions, and held option and was able to boot into windows 10. When I reboot this morning into OS X and try to select the startup disk with no avail. I get the bless tool error.

I have done this with win 8 on my mac pro so I am not new at this. Still trying to work it out. it seems to be a lot of
trial and error.

I thought i had it working but as soon as I boot in OS X i have the same trouble:

You can't change the startup disk to the selected disk. The bless tool was unable to set the current boot disk.

All along i was able to option boot while installing to select the windows disk.

 

[bergui45]

yjchua95 reported:

For Thunderbolt drives, just boot from the Windows USB installer and install directly onto the TB drive. Windows sees TB drives as an internal PCIe connection. However, you must format the TB drive as GPT first.


CAUTION: Windows can only be installed in UEFI flawlessly on Haswell Macs and later. Ivy Bridge and earlier Macs can only run Windows in BIOS-CSM flawlessly.
Attempts to boot a UEFI installation of Windows on an Ivy Bridge or earlier Mac will result in driver issues.


UEFI-compatible Macs:

MacBook Air (mid-2013 and later)

iMac (late-2013 and later)

Retina MacBook Pro (late-2013 and later)

Mac Pro (trashcan shape)

Mac Mini (late-2014 and later)


Non-retina MBPs are not UEFI compatible.

Before installing MBR on the TB SSD drive i disconnected both internal disks of my mid 12 MBPro 15" so the windows installer can only see the SSD external TB and will not overwrite your MacOS internal drive!