4 Replies Latest reply: Feb 3, 2014 6:00 PM by Kevtg
mikewh2 Level 1 Level 1 (0 points)

I finally figured out how to install and run Win 7 off of my thunderbolt drive (seagate). 


the rMBP requires a FAT partition to be created on the interal SSD.  If you use bootcamp utility it creates a huge 20GB partition.  I was able to create a small FAT partition on the internal SSD and then proceed to install and run win 7 off of the external thunderbolt drive. 




1.  run diskutil command:




diskutil list

you will need to know if your internal SSD is disk0 or disk1 (in this guide it was disk0


2.  Create the small partition:

***my ssd is a 512 GB drive, you can break down the partition here ***




diskutil resizevolume /dev/disk0s2 494G MS-DOS FAT 5G

3.  Within Mac, create a single msdos partition on the external thunderbolt drive.  (GUID or MBR)


4.  for the rMBP, use the Bootcamp assistant utility to create your USB windows 7 installer from an iso and also with the bootcamp drivers.


5.  Reboot and press the option key at the chime.


6.  Choose the windows installer


7.  at the drive screen of the installer you will see your 2 drives. drive0 maybe the external.  Format the external drive ntfs and then install to the drive.


8.  On reboot and eventually install bootcamp drivers.


Trial and error:

I tried install without internal partition and received 0x8030024 error which in some of apple forums can be overcome by removing the main drive.  I did this but installer would freeze.


Good luck.  If you need any help let me know.


see forum for complete disscussion



MacBook Pro with Retina display, OS X Mountain Lion, 2.7ghz 512 gb SSd, 16gb ram
  • luai e Level 1 Level 1 (10 points)

    I just followed your steps and everything went fine. Thank you for your post. It was very helpful.


    I have a question and a comment.



    The same steps worked out fine with me while using disk utility not the terminal. So if anyone does not like the shell command s/he can partition the SSD using the disk utility app.



    after following your steps, now I have the 20 GB (small partition). Can delete it or it is going to miss up everything?


    again thank you again.

  • luai e Level 1 Level 1 (10 points)

    I tried deleting the small FAT partition after installing windows and I screwed everything. So my recomendation for all of you to make the partition as small as u can (I did 10GB)

  • battlegiraffe Level 1 Level 1 (0 points)

    I have a related question. I have a 2012 top-of-the-line iMac with Thunderbolt, and I already have the internal SSD partitioned into both Mac and Bootcamp running Windows 7 64 bit. The internal hard drive is also partitioned into both mac and PC hard drives  I just added a 4 TB external Thunderbolt drive (Seagate Backup Plus using the external Seagate Thunderbolt adapter/dock), and I do NOT want to install Windows bootcamp on the external drive - I just want to partition it so that the Mac has access to 2 TB and Bootcamp has access to the other 2 TB. Using Mac Disk Utility, I can easily partition it, although I can't format the PC side into NTSF. However, when I startup using Windows, it doesn't seem to recognize either of the external hard drive partitions that the Mac side already recognizes. The Mac side even assigned little icons (automatically) to both partitions showing the Seagate harddrive docked in its little Thunderbolt adapter/dock. The PC side didn't assign icons, and didn't recognize either partition UNTIL I WENT INTO PC DISK MANAGEMENT AND FORMATTED THE PC PARTITION AGAIN, as NTSB.  Now the PC side recognizes the Windows Partitions, but still doesn't recognize the Mac partition - it says that partition hasn't been formatted yet. Oddly, the Mac side still recognizes both partitions even after I changed the PC version. So what's going on here? Does Windows require some sort of Thunderbolt driver in order to correctly recognize an external hard drive that Mac Disk Utility has formatted? I didn't have this problem on the internal hard drive that come in my iMac - it's recognized easily by both PC and Mac.


    I am using only the Windows NTSF partition on the external hard drive at the moment. I transferred all my Steam games to it as an experiment (about 350 GB). The games are running just fine, but it seems that the frame rates and speeds are slower than they were on the original internal hard drive. I bought the external Thunderbolt drive because it was supposed to be faster.


    Anyone have any suggestions?


    Any help on this matter would be appreciated. Thanks!

  • Kevtg Level 1 Level 1 (0 points)

    Mikewh, did you see my reply to you OP on macrumors?



    I am having an issue with the Windows boot hanging with a blinking cursor. It seems like you have done this quite a bit. I'd sincerely appreciate your assistance