I want to copy my W7 Bootcamp partition to an external HDD, and be bootable of course. It is currently functioning fine alongside Yosemite on a different HDD.

DiskUtility Restore works... I marked the partition as active... But the new Bootcamp partition is still not recognized on start-up.

Please help!


  1. Currently using (and working from) Yosemite OSX10.10.2 on an internal SSD.
  2. Source: HDD1 (external-USB) works fine and can boot as W7 or Yosemite. This is the original Bootcamp partition I want to clone or copy.
  3. Destination: HDD2 (external-USB) is blank and much larger than the HDD1 Bootcamp partition. This is the drive I'd like to copy my Bootcamp partition to and have it bootable.
  4. The HDD1 Bootcamp partition was origninally made with OSX10.6.8.

I have tried:

  1. Formatting HDD2 as GUID-FAT32; using DiskUtility to 'restore' the HDD1 bootcamp partition to; using sudo fdisk to mark as active; everything seemed to go great but it doesnt get recognized upon boot-up.
  2. Same as above but formatting HDD2 as MBR-FAT32.
  3. Running disk repair after step 1, looks good.

My fdisk commands: sudo fdisk -e /dev/disk1; p; setpid 1; 07; flag 1; p; write; y ...seems to work. See attached image.

What am I missing???

Thanks in advance. fdisk commands

  • You have no code in the MBR on disk1. You can confirm this by entering the command sudo dd if=/dev/disk1 count=1 bs=446 | xxd. A result of all zeros would indicate a problem. What is the Model/Year of your Mac? I also assume you disconnected the original external disk before trying to boot to the new external disk. Finally, I am surprised you have been able to boot Windows on an external disk. I thought that was not possible. Commented Apr 12, 2015 at 4:31

2 Answers 2


Windows 7 will not run from an external USB hard drive. This is a limitation of Windows, not your Mac. Windows can ONLY run from an internal, non-removable hard drive. That limitation applies even on a real PC.


Thank you both for your replies, they helped my investigation. (David Anderson and Wes Sayweed)

There are many reports of both W7 and W8 running bootable from an external drive. I hoped that with the proper disk setup, activation, and EFI settings I could accomplish this, but I have discovered the barrier: you need a usb3 or thunderbolt connection, it cannot be done with usb2 by a limitation of windows itself.

BTW, W8.1 officially includes support for booting from an external drive. Running W7 that way appears to require a couple extra steps.

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