Resolved rMBP, Bootcamp off thunderbolt drive - MORE COMPLETE SOLUTION

[Max108]

No, I tried a lot to solve that problem (was ages ago now).

I ended up using the 2x 256Gb ssd's as separate drives in the end.
One for OS X and the another one for games for Windows, I installed Windows 8 with bootcamp on the internal drive.

Thanks Gascogne for your reply. I was reading on a thread that you continued on after this one that you got a bit further than me by connecting an external dvd drive to install from. However, it was later suggested by Superangel Mac that there was another method that meant it didn't matter whether you used a USB or DVD to install.

With your experience then, do you recommend I go to some difficulty and perhaps expense to get an external DVD drive to install from, or do you think that it's not really worth it?

 

[Gascogne]

Thanks Gascogne for your reply. I was reading on a thread that you continued on after this one that you got a bit further than me by connecting an external dvd drive to install from. However, it was later suggested by Superangel Mac that there was another method that meant it didn't matter whether you used a USB or DVD to install.

With your experience then, do you recommend I go to some difficulty and perhaps expense to get an external DVD drive to install from, or do you think that it's not really worth it?

I would say it's not worth getting an external dvd drive, it didn't solve the install problem (at least not for me).

But I think I read recently somewhere that someone had solved the situation with windows on external drive.

*edit*
Found it.
I haven't tried this myself tho.

Windows on external drive

 

[Max108]

I would say it's not worth getting an external dvd drive, it didn't solve the install problem (at least not for me).

But I think I read recently somewhere that someone had solved the situation with windows on external drive.

*edit*
Found it.
I haven't tried this myself tho.

Windows on external drive

Thank you Gascogne for looking this up for me.

I'll look for an installer that has the necessary install.wim file for the procedure described and give it a go.

 

[neosynthesis]

It worked on MacBook Pro Retina 15! but

*edit*
Found it.
I haven't tried this myself tho.

Windows on external drive

Thanks for the link, Gascogne.

On my 2012 MacBook Pro Retina 15, the linked instructions worked perfectly with Windows 8. BUT this method seems to be targeting USB connectivity as opposed to thunderbolt. Following the instructions resulted in a bootable Windows 8 drive when it's in a USB 2.0 enclosure. Connecting same drive to a thunderbolt adapter (Seagate STAE 121, bare drive) boots to a black screen with a single blinking white cursor.

So far the only way I found for me to get the same hard drive to boot via thunderbolt was to create a small unused partition on my internal MBPr SSD following the instructions from the original post of this thread.

Since I only have 256GBs of SSD, I wanted to minimize size of the additional internal partition necessary for bootcamp. The smallest I was able to get away with through numerous trials was 700MB.

I used this terminal command:
diskutil resizevolume /dev/disk0s2 249.4G MS-DOS FAT 0.7G

I'm all ears if anyone else has found a way to make it work without modifying the internal SSDs partition table.

Happy bootcamping everyone! 🙂

 

[Max108]

Thanks for the link, Gascogne.

On my 2012 MacBook Pro Retina 15, the linked instructions worked perfectly with Windows 8. BUT this method seems to be targeting USB connectivity as opposed to thunderbolt. Following the instructions resulted in a bootable Windows 8 drive when it's in a USB 2.0 enclosure. Connecting same drive to a thunderbolt adapter (Seagate STAE 121, bare drive) boots to a black screen with a single blinking white cursor.

So far the only way I found for me to get the same hard drive to boot via thunderbolt was to create a small unused partition on my internal MBPr SSD following the instructions from the original post of this thread.

Since I only have 256GBs of SSD, I wanted to minimize size of the additional internal partition necessary for bootcamp. The smallest I was able to get away with through numerous trials was 700MB.

I used this terminal command:
diskutil resizevolume /dev/disk0s2 249.4G MS-DOS FAT 0.7G

I'm all ears if anyone else has found a way to make it work without modifying the internal SSDs partition table.

Happy bootcamping everyone! 🙂

Hi neosynthesis,

I'm trying to connect and early 2013 MacBook Pro to a 1TB (2x500GB drives) LaCie Little Big Disk. To simplify things, I only plan to use one of the 500GB's for the external Bootcamp but, of course, I want to use the Thunderbolt connection. Windows 8 would be fine and, because I'm on a MacBook Pro, I recognise the need in my case for a tiny internal partition, which I've made.

The trouble for me is that the Windows 8 installer I've been trying to use recognises the 500GB drive and will even format it but, I think because it's a LaCie, it requests additional drivers when I ask to install to it.

Any suggestions?

 

[neosynthesis]

Hi neosynthesis,
...
The trouble for me is that the Windows 8 installer I've been trying to use recognises the 500GB drive and will even format it but, I think because it's a LaCie, it requests additional drivers when I ask to install to it.

Any suggestions?

Sorry friend. I really would love to help you out but without hardware even remotely similar to your LaCie, I just wouldn't be able to spend the time to experiment with it.

Sounds like you need a way to inject drivers into your Win8 installation image BEFORE the actual installation so as Win8 installs, your LaCie drivers will be installed with it. Am I right?

The closest solution I can find to your scenario would be this:
http://technet.microsoft.com/en-us/library/hh825109.aspx
and see the sub section for adding drivers.

In all honesty, I would probably just invest in a plain, single disk USB3 drive WITHOUT the complexity of RAID needing additional drivers, wasting more of your previous time (use a SSD if you want performance. FYI, my bootcamp on external drive via thunderbolt is a 160GB, 5 year old 5400rpm 2.5HD from my old Macbook. No issues with Win7 64bit and Borderlands 2).

I'm sure your time is worth a lot more than trying to force 2 never-intended-to-work-this-way-in-the-1st-place solutions into a package. I'm already counting my blessings to actually get my bootcamp on an external drive, let alone a RAIDED one.

Many, MANY thanks to all the helpful folks here! 🙂

Best of luck, Max.

 

[Max108]

Sorry friend. I really would love to help you out but without hardware even remotely similar to your LaCie, I just wouldn't be able to spend the time to experiment with it.

Sounds like you need a way to inject drivers into your Win8 installation image BEFORE the actual installation so as Win8 installs, your LaCie drivers will be installed with it. Am I right?

The closest solution I can find to your scenario would be this:
http://technet.microsoft.com/en-us/library/hh825109.aspx
and see the sub section for adding drivers.

In all honesty, I would probably just invest in a plain, single disk USB3 drive WITHOUT the complexity of RAID needing additional drivers, wasting more of your previous time (use a SSD if you want performance. FYI, my bootcamp on external drive via thunderbolt is a 160GB, 5 year old 5400rpm 2.5HD from my old Macbook. No issues with Win7 64bit and Borderlands 2).

I'm sure your time is worth a lot more than trying to force 2 never-intended-to-work-this-way-in-the-1st-place solutions into a package. I'm already counting my blessings to actually get my bootcamp on an external drive, let along a RAIDED one.

Many, MANY thanks to all the helpful folks here! 🙂

Best of luck, Max.

Thank you for your considered and friendly reply. Having already invested in the LaCie (not cheap!) I'll think I'll just persevere with it. There are a few avenues that I've yet to explore so I've not given up hope yet. Wish me luck!

 

[biohead]

I've got a Mybook Duo thunderbolt which works fine for bootcamp. During install it can see both drives inside the enclosure (Drive 0 and 1 - Drive 2 is my internal drive), and works as is - no prompting for drivers.

I did see your problem being mentioned with the LBD when I was looking into what thunderbolt solution to buy. I never saw a solution unfortunately. 🙁 What neosynthesis is saying about injecting the drivers into the install image does seem like a good shot though.

And for general info: with most of these multiple drive thunderbolt enclosures, you'll never get Windows installed to the RAID. Most of the enclosures simply use software raid provided by OS X or Windows - there's no hardware raid feature in the enclosure itself (possibly on the more expensive ones though - pegasus?). I've read that it's possible to get a raid1 setup with the boot disk, but raid0 is not possible.

 

[Max108]

Sounds like you need a way to inject drivers into your Win8 installation image BEFORE the actual installation so as Win8 installs, your LaCie drivers will be installed with it. Am I right?

The closest solution I can find to your scenario would be this:
http://technet.microsoft.com/en-us/library/hh825109.aspx
and see the sub section for adding drivers.

I should have thanked you for this especially - I haven't tried it yet but I'm hopeful. I had just about abandoned a direct install in favour of an implanted image from a provisionally internal bootcamp installation, but this breathes new hope.

I've got a Mybook Duo thunderbolt which works fine for bootcamp. During install it can see both drives inside the enclosure (Drive 0 and 1 - Drive 2 is my internal drive), and works as is - no prompting for drivers.

I did see your problem being mentioned with the LBD when I was looking into what thunderbolt solution to buy. I never saw a solution unfortunately. 🙁 What neosynthesis is saying about injecting the drivers into the install image does seem like a good shot though.

And for general info: with most of these multiple drive thunderbolt enclosures, you'll never get Windows installed to the RAID. Most of the enclosures simply use software raid provided by OS X or Windows - there's no hardware raid feature in the enclosure itself (possibly on the more expensive ones though - pegasus?). I've read that it's possible to get a raid1 setup with the boot disk, but raid0 is not possible.

Thank you for the information. The learning curve of trying to achieve an external install on my set up had led me to abandon a RAID setup very quickly for the reasons you explain. I'm aiming now to install on just one of the 2 SSDs contained in the enclosure and using the other for editing movies and perhaps a time-machine backup.

----

If I have any success with installing the drivers I'll let you know.

 

[neosynthesis]

I should have thanked you for this especially - I haven't tried it yet but I'm hopeful. I had just about abandoned a direct install in favour of an implanted image from a provisionally internal bootcamp installation, but this breathes new hope.



Thank you for the information. The learning curve of trying to achieve an external install on my set up had led me to abandon a RAID setup very quickly for the reasons you explain. I'm aiming now to install on just one of the 2 SSDs contained in the enclosure and using the other for editing movies and perhaps a time-machine backup.

----

If I have any success with installing the drivers I'll let you know.

Don't mention it, Max. I personally benefited so much from all the people who donated their time to this thread that I feel disappointed not being able to help you out more.

Best of luck and I trust your findings will serve others here, too!

 

[Kevtg]

Ghost or full install?

First of all, I am so glad that everyone has contributed so much to this thread. I have a 2012 retina MacBook Pro. I am using a Seagate go flex. I am having a lot of trouble getting the laptop to boot into windows when my thunderbolt Drive is attached. The same problem is reproducible, whether I installed boot camp as a partition on my internal drive, or use the windows installer to target an NTFS partition on the external drive. The windows installer will recognize the thunderbolt Drive, but booting into windows causes a hang on boot. There is a black screen with a blinking cursor.

I have seen that other people all around the Internet have experienced a blinking cursor when booting into windows with a thunderbolt attached. I have not seen a clear description of a resolution to this problem. 😎 😱 I would assume this is GoFlex issue, if not for others claiming they successfully use the GoFlex for Win7 boot or external Windows TBolt storage

So that we can all get started on the same foot, of those who have gotten a functioning bootable thunderbolt windows Drive, did you use the windows install method or did you install windows to an internal partition, then migrate to the external drive?

The reason I have quoted Mikewh is that he (you, Makewh!) has said that he has done this successfully, but after reading subsequent posts in this thread, I cannot ascertain which technique successfully boots MacOS internal + Windows external.

At this point, I would like to summarize the (THREE) methods that seem to circulate here and elsewhere:

1) create tiny FAT32 partition on internal drive, then boot Win install and install to external drive. In this version, windows automatically places the boot sectors in the internal drive.
2) Create Bootcamp (or manual) internal partition large enough for Windows. Install Windows to internal drive. Drivers. Clone to external drive. Delete internal partition. Boot to external
3) create tiny FAT32 partition + primary Windows partitions on EXTERNAL drive. Manually image (using imagex.exe or other) the boot sectors and windows install files to their respective partitions.

I have tried each version, but have gotten stopped up at similar stages in each.
In 1, the install nearly completes, but once it is time to boot from the Thunderbolt drive, the boot hangs at the blinking cursor.
In 2, the install completes and I boot into Win7, but Windows does not recognize my Thunderbolt drive. It doesn't matter the format. Bootcamp could see HFS+ even IF it were formatted that way, which it is not. If I insert the GoFlex before boot, Windows hangs on blinking cursor.
In 3, I could not get Imagex.exe to work correctly (seemed to work, but only in x86 and after 7 hours, indicated 20% progress during image creation). I tried simply booting from USB install, using the boot and primary Thunderbolt partitions I created using cmd in Parallels. I get a blinking cursor on boot after install completes.

I have invested a lot of time trying to get this to work. I have definitely spent an equal amount of time scouring forums, so I appreciate any help offered.

Here's what I've done.

1. Created Bootcamp partition on internal ssd with utility and installed windows
2. After install of bootcamp drivers rebooted
3. Plugged in thunderbolt cable with Seagate adapter and 480gb SSD and booted into "native" bootcamp
4. Deleted all partitions of 480gb SSD and made unallocated
5. Rebooted
6. Used Norton Ghost version 15 to copy bootcamp partition to 480gb ssd with transfer of MBR and unassigned drive letter.
7. After successful transfer, stopped and removed thunderbolt drive
8. Rebooted in to mac and removed bootcamp partition with utility
9. Rebooted and tried to load bootcamp from thunderbolt and came to black screen with cursor.

I've done everything from the different forum but still no success. I think possibly the rMBP may not allow the booting of bootcamp via thunderbolt or there may be a driver issue.

any guidance or thoughts.

 

[Kevtg]

from just above

absolutely. using my method of a small internal partition and then install to the thunderbolt. see beginning of thread for method.

This method (which I describe as Method 1, above) causes my system to hang on boot, after Win7 installs to the external drive.

 

[Kevtg]

perhaps..

AND MAKE IT BOOTABLE/ ACTIVE. That is the key part. I don't know how to make a partition active in OS X but just used a bootable Ubuntu stick and ran gparted, then set the boot flag.

While in gparted, I created a new ms-dos (MBR) partition table on the thunderbolt SSD and made 1 partition. Booted into the Windows 8 installer, formatted the new SSD partition to NTFS and finally it installed!

I guess it is possible that the FAT32 partition I made on my internal drive was not ACTIVE, but I did confirm that Win7 unpacked the boot files there, as I could see them (if I unhide the hiddens) in MacOS...

Any thoughts here before I go again are greatly appreciated...🙄

 

[Kevtg]

I guess it is possible that the FAT32 partition I made on my internal drive was not ACTIVE, but I did confirm that Win7 unpacked the boot files there, as I could see them (if I unhide the hiddens) in MacOS...

Any thoughts here before I go again are greatly appreciated...🙄

Well, I tried again, this time using command-line before win7 setup to make Active the internal FAT partition. I used the command-line feature built into the repair utility in win7 install.

boot hangs after install with blinking cursor 🙁

 

[Mikewh]

Well, I tried again, this time using command-line before win7 setup to make Active the internal FAT partition. I used the command-line feature built into the repair utility in win7 install.

boot hangs after install with blinking cursor 🙁

I haven't played around with this for some time. I will look back at my notes and get back to your post. It may take me through the weekend. I've been very busy this week.

Mikewh

 

[Cloudane]

For things like making a partition active I use a Linux live CD/USB with "gparted" on it. It's usually listed as "Partition Editor" or something like that in the menus.

Don't know if they're of any help, but here are my notes from last time, when I did Windows 8.1 on it from start to finish with a freshly installed OS X. There are probably more reboots etc than necessary, but they're the steps that worked for me. I use half the disk for Windows and half for storage.

Installing Windows to external

Prepare Ubuntu and Windows 8.1 pendrives.

Install RefIt, reboot, check it's working.
OS X disk utility, add a minimum size (1.07GB) partition, formatted as MS-DOS, labelled BOOTCAMP
Reboot, at RefIt menu choose disk partitioner and sync GPT+MBR tables
Boot Ubuntu (Hold Alt key on start and choose the EFI Boot option for the pendrive). Use “Try without installing” mode.
Run GParted
Go to the partition flags and enable the BOOT flag on the BOOTCAMP partition.
Plug in the Thunderbolt drive and reboot.
At the RefIt menu choose disk partitioner and sync GPT+MBR tables again
Boot Ubuntu again (Alt key and choose the EFI Boot option for the pendrive). Use “Try without installing” mode.
Run GParted
On the external drive, create a new partition table and make sure the parition table type it's set to “ms-dos” (MBR) as default.
Create a new partition for half the disk (or whatever you wish) as NTFS, labelled Windows.
Reboot, at RefIt menu swap the Ubuntu stick for the Windows stick and choose the reboot option, this time with
Alt held down.
For the Windows boot, be sure to pick the standard Windows option on the USB device (NOT the EFI Boot one,
this doesn't work… the Mac seems to make even a GPT drive appear as an MBR one, causing Windows to throw an error)

When Windows setup is asking which drive to install on, format the Windows partition and it should allow
installation to it.
If it doesn't:
1) Is there a 300MB+ FAT32 partition on the internal drive
2) Is the 300MB+ FAT32 partition marked with the BOOT (Active) flag?
3) Did you choose the standard Windows boot from the USB stick, NOT the EFI one?
4) Is the target Windows partition formatted?
5) The external SSD is definitely partitioned as MBR, not GPT?

 

[Kevtg]

The Thunderbolt-PC for rMBP guide

Link to complete guide on Tumblr

Thanks for the reply Cloudane! I appreciate your detailed help. I was definitely considering a boot manager like rEFIt. I may still use your instructions, later, to install a Linux copy (triboot) on another external drive. My Windows version works!

I did nothing new except download a fresh copy of Windows 7 Enterprise. I don't recall how I came upon my original Windows USB stick. It is one I have used to install Windows 7 on a variety of internal drives and has always worked perfectly. Luckily, University of Michigan runs a KMS authorization service for Windows 7 Enterprise. I will say that though this installation appears to work and perform very smoothly (Thunderbolt to SATA SSD has basically just a SATA bottleneck), my subsequent install of ArcGIS 10.1 is currently VERY slow and buggy. I guess we have to take this bird-by-bird.

Anyway, I will go ahead and include, below, the steps I used to get Windows running off an external Thunderbolt drive on a 2012 rMBP. This is an homage to all who have tried and succeeded before me 🙄😀

In order for my solution to work, we use #1, summarized above: create tiny FAT32 partition on internal drive

THE GUIDE

1) Create the FAT32 partition:

• you can use Disk Utility or Terminal to resize your MBP internal drive

A to use Disk Utility​

• Open it from Applications>>Utilities
• select the Drive from the top of the hierarchy
• click the "Partition" tab
• in the "size" box on the left hand side of the pane, subtract 1.0GB from the current size of your internal drive. For example, my drive read 250.14. In this box, I typed 249.0 You can actually shrink it by as little as 400MB, but I left a little buffer. This is going to allow you to create a new FAT parition into which Windows will automatically place boot files
• click "Apply"
• now, click the new blank area below the main partition. Format it to MS-DOS FAT 32

B. to use Terminal (faster, but less visual)​

• open terminal: Apps>>Utilities
• Type: diskutil list <enter> You need 2 pieces of information from the resulting table: 1) the size of your main partition and 2) the name of your internal partition (e.g. disk0s2 or whatever) Don't F this up. But if you're typing in terminal you already know that you should be precise anyway
• now, execute the resize volume command: diskutil resizeVolume disk0s2 249G MS-DOS FAT 1.1G
• now you have an internal FAT32 "sliver." Confirm this with diskutil list <Enter>

Now, there is a SECOND step NOT to be missed: tagging this tiny internal partition as "Active" for the Windows install. As far as I can tell, OSX does not have this function. Others have used Ubuntu and gparted (thanks Cloudane), but as I find Windows command-line pretty friendly AND your Windows install USB/DVD comes with the utility, I use that function. My method is detailed in step 4, below.

2) Create (if you haven't already) your USB Windows install disk. Go ahead and use Bootcamp utility for this.

• Just make sure, in the first window, you deselect the last option for "create Bootcamp partition and install Windows."
• so, select "Create Windows 7 or later ... " and "download the latest Windows support..."
• deselect the last option
• this will take a while.
• Sometimes, the utility has trouble getting the support software from Apple. This is fine. You have already created the boot disk. BUT, this means you have to download the Bootcamp drivers manually. Google it! Then copy the Bootcamp_version-whatever onto your USB stick

3) Boot to Windows install. Restart your computer, holding the Opt key at the perfect moment! Select to boot from the USB "windows" drive

4) Mark internal "sliver" as active. Now, after it boots, click to select your language BUT then we need to enter the "Repair utility" to set the small FAT sliver inside the computer to "active"

1. After you hit "Repair," go ahead and skip all the automatic options, so that you can use command-line.
2. In order now...
3. diskpart <enter>
4. list disk <enter>
5. select disk # <enter> --in place of "#," your internal disk listed
6. list partition <enter>
7. select partition # <enter> --in place of "#," the small FAT partition we created
8. active <enter>
9. assign letter=a (or whatever) <enter>
10. exit <enter>

5) Restart computer, hold option at the perfect moment. Select the USB Windows disk again. Enter Windows setup

6) Obviously, select a "Custom install," when presented with the option, so you can select your external disk to install. Do not install on your internal sliver or any other ridiculous thing.

• before it will let you install, it will obviously make you format the external disk as NTFS. Go ahead and format the whole drive, if you don't already have it partitioned. The format preserves exisitng partitions, BUT if you want to create others (perhaps to share with you Mac side) later, you can resize your primary NTFS partition within Windows later

7) Finish the Windows install. Each time it reboots, you will need to hold down the option key to choose to boot to: the new Windows volume you have created during the install. Don't boot to your USB stick anymore.

8) Install bootcamp drivers automatically by double-clicking the setup or autorun or whatever inside the USB stick folder you (or OSX) created


As a sort-of check if you are still having trouble, in OSX, run: diskutil list from the Terminal. If your table does not look like mine, ask yourself, "Why self?"

For things like making a partition active I use a Linux live CD/USB with "gparted" on it. It's usually listed as "Partition Editor" or something like that in the menus.

Don't know if they're of any help, but here are my notes from last time, when I did Windows 8.1 on it from start to finish with a freshly installed OS X. There are probably more reboots etc than necessary, but they're the steps that worked for me. I use half the disk for Windows and half for storage.

Installing Windows to external

Prepare Ubuntu and Windows 8.1 pendrives.

Install RefIt, reboot, check it's working.
OS X disk utility, add a minimum size (1.07GB) partition, formatted as MS-DOS, labelled BOOTCAMP
Reboot, at RefIt menu choose disk partitioner and sync GPT+MBR tables
Boot Ubuntu (Hold Alt key on start and choose the EFI Boot option for the pendrive). Use “Try without installing” mode.
Run GParted
Go to the partition flags and enable the BOOT flag on the BOOTCAMP partition.
Plug in the Thunderbolt drive and reboot.
At the RefIt menu choose disk partitioner and sync GPT+MBR tables again
Boot Ubuntu again (Alt key and choose the EFI Boot option for the pendrive). Use “Try without installing” mode.
Run GParted
On the external drive, create a new partition table and make sure the parition table type it's set to “ms-dos” (MBR) as default.
Create a new partition for half the disk (or whatever you wish) as NTFS, labelled Windows.
Reboot, at RefIt menu swap the Ubuntu stick for the Windows stick and choose the reboot option, this time with
Alt held down.
For the Windows boot, be sure to pick the standard Windows option on the USB device (NOT the EFI Boot one,
this doesn't work… the Mac seems to make even a GPT drive appear as an MBR one, causing Windows to throw an error)

When Windows setup is asking which drive to install on, format the Windows partition and it should allow
installation to it.
If it doesn't:
1) Is there a 300MB+ FAT32 partition on the internal drive
2) Is the 300MB+ FAT32 partition marked with the BOOT (Active) flag?
3) Did you choose the standard Windows boot from the USB stick, NOT the EFI one?
4) Is the target Windows partition formatted?
5) The external SSD is definitely partitioned as MBR, not GPT?

 

[Kevtg]

When asking: "why self? why is this process not working?" Cloudane's troubleshooting questions below are the ONLY ones to be asking. If you have satisfied all these criteria, there i something wrong with your Windows install disk ISO source

For things like making a partition active I use a Linux live CD/USB with "gparted" on it. It's usually listed as "Partition Editor" or something like that in the menus.

Don't know if they're of any help, but here are my notes from last time, when I did Windows 8.1 on it from start to finish with a freshly installed OS X. There are probably more reboots etc than necessary, but they're the steps that worked for me. I use half the disk for Windows and half for storage.

Installing Windows to external

Prepare Ubuntu and Windows 8.1 pendrives.

Install RefIt, reboot, check it's working.
OS X disk utility, add a minimum size (1.07GB) partition, formatted as MS-DOS, labelled BOOTCAMP
Reboot, at RefIt menu choose disk partitioner and sync GPT+MBR tables
Boot Ubuntu (Hold Alt key on start and choose the EFI Boot option for the pendrive). Use “Try without installing” mode.
Run GParted
Go to the partition flags and enable the BOOT flag on the BOOTCAMP partition.
Plug in the Thunderbolt drive and reboot.
At the RefIt menu choose disk partitioner and sync GPT+MBR tables again
Boot Ubuntu again (Alt key and choose the EFI Boot option for the pendrive). Use “Try without installing” mode.
Run GParted
On the external drive, create a new partition table and make sure the parition table type it's set to “ms-dos” (MBR) as default.
Create a new partition for half the disk (or whatever you wish) as NTFS, labelled Windows.
Reboot, at RefIt menu swap the Ubuntu stick for the Windows stick and choose the reboot option, this time with
Alt held down.
For the Windows boot, be sure to pick the standard Windows option on the USB device (NOT the EFI Boot one,
this doesn't work… the Mac seems to make even a GPT drive appear as an MBR one, causing Windows to throw an error)

When Windows setup is asking which drive to install on, format the Windows partition and it should allow
installation to it.
If it doesn't:
1) Is there a 300MB+ FAT32 partition on the internal drive
2) Is the 300MB+ FAT32 partition marked with the BOOT (Active) flag?
3) Did you choose the standard Windows boot from the USB stick, NOT the EFI one?
4) Is the target Windows partition formatted?
5) The external SSD is definitely partitioned as MBR, not GPT?

 

[nameaneh]

rMBP different than MBP?

I have a mid-2011 MBP and successfully installed Windows 7 on a Thunderbolt drive. Admittedly I didn't take the time to read thru all of the previous comments, but if the Retina is the same as my MBP, I could maybe explain how I was able to do it?

 

[Cloudane]

I've been using Linux more and more and decided I could justify having Linux on my internal drive (alongside OS X) while leaving Windows on the external one. Naturally this meant rebuilding, and rethinking my strategy.

In the process I've found a few more thoughts, theories and observations.

As I understand it....

Items in the Mac boot menu (holding alt) are
a) Partitions on GPT-partitioned drives of partition type EF00 (EFI system). These are FAT32 or HFS+ formatted.
b) Partitions on MBR-partitioned and hybrid GPT+MBR drives that are marked 'active' (bootable)

Booting from a) is in EFI mode. Booting from b) sets BIOS emulation mode.
Windows on a Mac, despite supporting standard UEFI, doesn't appear to support Apple EFI, so only works in BIOS emulation mode.

Windows 8 has two modes:
When booted from EFI, it must be installed to a GPT partitioned disk.
When booted from BIOS emulation, it must be installed to an MBR partitioned disk.

When you set up Windows on a Mac, it has to be in BIOS mode, so it has to see BOTH the internal and external drives as valid MBR drives.

The internal drive is GPT partitioned (as required by OS X), and the way to get around this is called a "Hybrid GPT/MBR" drive. This means the drive is partitioned to the newer GPT system, but also has an MBR for backward compatiblity. If you want to access a GPT defined partition via MBR, the MBR has to have the exact same start and end sectors and a compatible filesystem type. Basically, it's like two indexes to the same book.
Naturally, this is dangerous, and Linux tools will warn you as such. If the MBR gets out of sync and an OS sees what it thinks is "free space" and uses it, or sees what it thinks is unformatted and wipes it, it can wipe out your data.

By default, your internal drive on a Mac gets a GPT table and a hybrid MBR with just one partition, type EE, covering the full drive. This is just so that MBR based operating systems don't see your drive as empty and write data to it, instead they see it as type unknown and ignore it. It's more commonly known as a "protective MBR".

The Refit/Refind package removes the protective MBR and instead maps the MBR to the same layout as the GPT as best it can. Make sense? (Clear as mud, I know).

When it does so, it translates type EF00 (EFI) partitions on the GPT to Active partitions on the MBR. Interestingly, remember when I talked about going into gparted and marking the 300MB+ "bootcamp" partition with the "Boot" attribute? What this ACTUALLY does is change the partition type in the GPT from 0700 (Windows data) to EF00 (EFI). Both are still Fat32 format! And GPT doesn't really have a concept of an 'active/boot' flag, rather, that's what EFI partitions are for. It's just the partition type changes.

=== WHEW ===

The kicker was when I threw an internal Linux partition into the equation, BUT I forgot that you can only have 4 Primary partitions on an MBR disk, and so when you do the sync from refit (or gptsync which you can get from refit in Linux) it only translates the first 4 partitions.

Here was my GPT layout:
1: EFI partition for OS X, type EF00
2: OS X System, type AF00
3: OS X Recovery, type AB00
4: Linux, type 8300
5: Linux EFI Boot, type EF00
6: BOOTCAMP (Windows boot), size 400MB, type EF00

gptsync bombed out because it doesn't recognise type 8300 (which seems silly, must be a bug) so I had to temporarily change the Linux partition to type 8301 in any case (Linux Reserved). But then even when it did work, it only translated the first 4 partitions. Oops! The MBR can't see partition 6!

Here is the correct GPT layout:
1: EFI partition for OS X, type EF00
2: OS X System, type AF00
3: OS X Recovery, type AB00
4: BOOTCAMP (Windows boot), size 400MB, type EF00
5: Linux EFI Boot, type EF00
6: Linux, type 8300

Now BOOTCAMP is on partition 4, type EF00, so it's translated to FAT32/Active on the MBR, and Windows installs. I now finally (after figuring out how to get Arch Linux to boot directly from an EFI boot partition instead of going via BIOS emulation, so it appears in the Mac's ALT menu) have a triple boot going. Windows external, OS X and Linux internal.

Refit was only really necessary for gptsync, which is available in Arch Linux's AUR, so I'm also managing without Refit - everything is bootable from the ALT key menu.


I think I'm *starting* to understand how it works 😛

 

[maratus]

Thanks to everyone in this thread for very helpful info. I've managed to install Windows 8.1 in EFI mode on my external Thunderbolt SSD without affecting bootloader on the internal SSD (rMBP, early-2013 with 650M)

Just to summarise my experience:

1. Create a small temporary FAT32 partition on the internal SSD in OS X Disk Utility. I assume that removing the internal SSD (or wiping it entirely) will have the same effect.

2. Boot from the USB installation drive

3. Clean the Thunderbolt SSD and manually create a 200MB EFI partition in DISKPART. Make sure to format it in FAT32 and not NTFS.

4. Install Windows 8.1 directly onto the "unallocated" space. Let the installer do its job, there's no need to manually create any other partition except the EFI partition from step 3.

5. After Windows installation, you can delete FAT32 partition from the internal SSD in OS X Disk Utility

6. Enjoy Windows 8.1 in EFI mode on the external SSD.

7. If you want to use a part of your Thunderbolt SSD for storage (I use exFAT supported natively by both OS X and Windows 8) I recommend to partition it in Windows.

 

[Max108]

@maratus, Thank you for taking the time to write this summary. It answers all my remaining questions after reading this thread.

Best wishes to you.

 

[El Jengibre]

@maratus, I'm trying to install the Windows 10 technical preview onto an external SSD connected by thunderbolt (though the GoFlex adapter) using your method, but so far it hasn't worked for me:

I accomplished step three in diskpart in the command prompt on the bootcamp-created usb stick by...
1. selecting the external drive and running CLEAN
3. running CONVERT GPT
4. running CREATE PARTITION EFI SIZE =200

All of that worked fine, but then when I tried to install Windows into the unallocated space, it gave me an error stating "windows cannot be installed on this disk. The selected disk is of the GPT partition style." The only way I could fix this was to run CLEAN and CONVERT GPT on the external drive without creating the EFI partition. Without the EFI partition, I can install and boot into Windows, but as soon as I delete the internal FAT32 partition in OS X, I can no longer boot into Windows.

My purpose for running Windows on an external drive is so that I can use it from either my macbook or an iMac I'm going to buy soon. As a result, I really don't want to allocate internal drive space on two machines to FAT32 partitions if I can help it.

Thanks

 

[yjchua95]

@maratus, I'm trying to install the Windows 10 technical preview onto an external SSD connected by thunderbolt (though the GoFlex adapter) using your method, but so far it hasn't worked for me:

I accomplished step three in diskpart in the command prompt on the bootcamp-created usb stick by...
1. selecting the external drive and running CLEAN
3. running CONVERT GPT
4. running CREATE PARTITION EFI SIZE =200

All of that worked fine, but then when I tried to install Windows into the unallocated space, it gave me an error stating "windows cannot be installed on this disk. The selected disk is of the GPT partition style." The only way I could fix this was to run CLEAN and CONVERT GPT on the external drive without creating the EFI partition. Without the EFI partition, I can install and boot into Windows, but as soon as I delete the internal FAT32 partition in OS X, I can no longer boot into Windows.

My purpose for running Windows on an external drive is so that I can use it from either my macbook or an iMac I'm going to buy soon. As a result, I really don't want to allocate internal drive space on two machines to FAT32 partitions if I can help it.

Thanks

Here's an alternative (works for both TB and USB drives, but a VM may not be able to connect to a drive over TB):

Connect external drive to Windows VM. You must have a Windows VM in VMware/Parallels/VBox, or a Windows PC. Any existing Windows environment will do.

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

Open elevated cmd.exe (run as admin)

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. Feel free to trash the VM once you're done too.

For best results, use USB 3/Thunderbolt. If you don't have USB 3, use Thunderbolt. If you have neither, stick back to the internal drive 🙂

Note: This method involves reformatting the entire external drive.

 

[El Jengibre]

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: