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Windows and Mac on external bootable drive

4660 Views 8 Replies Latest reply: Aug 15, 2012 8:21 AM by gentux RSS
appleiser Level 1 Level 1 (0 points)
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Apr 25, 2012 5:19 PM


I am looking for a way to have two partitions on an external drive, one being a bootable Mac partition, the other a bootable windows 7 partition. The two partitions will be used on two separate computers (I have a Mac that I will use the Mac partition with and I have a pc that I will use the windows partition with). I do not need to be able to access the windows partition from the Mac, or the Mac partition from the windows machine.


Is this setup possible? I have looked on the Internet but am getting conflicting theories. Will it work if I format the first partition is hfs+ and install Mac on that, then format the second as ntfs and install windows 7 on that? What partition scheme would I have to use?



  • BobTheFisherman Level 6 Level 6 (10,580 points)
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    Apr 26, 2012 7:26 AM (in response to appleiser)

    I believe Windows will not boot from an external drive.

  • Allan Eckert Level 8 Level 8 (39,485 points)
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    Apr 26, 2012 7:34 AM (in response to appleiser)

    My suggestion is to avoid all the complications of configuring a single disk for both and just get a disk for each platform. With the cost of disks where they are currently, it is not worth the hassle of of putting both on one disk.



  • ezollars Level 2 Level 2 (255 points)
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    Apr 26, 2012 4:17 PM (in response to appleiser)

    As I recall booting Windows from an external drive is not supported and Bootcamp is not going to offer up externals.  As well, while some individuals have reported getting a setup where they could boot Windows from an external drive, the methods for getting there were more than a bit involved.  I don't recall anyone mentioning also putting an OSX partition on the same external drive, though I would suspect that wouldn't be a problem since OSX can be booted from an external.


    I'd personally suggest going virtualization for Windows unless you really need Bootcamp to run native Windows directly on the hardware.  That's usually needed only for gaming, and certainly all of the virtualization solutions will let you put Windows on an external drive, including one you are booting OSX from.

  • mlise Calculating status...
    Currently Being Moderated
    May 26, 2012 9:33 AM (in response to appleiser)

    You can do it, it's easy and works really well. Use a Thunderbolt external drive and the USB install stick that Bootcamp makes. During the install, at each reboot, you need to hold the option key to select the new installation to boot from. If you've ever installed windows before on your mac, you'll be presented with the Windows Boot Manager to select which installation to boot from.

  • GeekBoy.from.Illinois Level 4 Level 4 (2,735 points)
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    May 26, 2012 7:09 PM (in response to appleiser)

    Let me see if I read things right...


    You have an external dirve with a MacOS partition and a Windows 7 Partition (most likely a drive that used to be in a Mac and had BootCamp on it).  You want to copy the Mac Partition onto a Mac, and copy the Windows Partition onto a PC and use the two separately.  Is this right?


    If so, the Mac side is fairly easy,  assuming that the version of MacOS installed on that external drive is as new as (or newer) that the version shipped with the Mac you are trying to copy it to.  I personally prefer SuperDuper for cloning my Mac volumes, but a number of other people use Carbon Copy Cloner (CCC).  Both tools work great for cloning one MacOS partition to another.  I use this to keep a regular backup of my MacOS volume, in case of a disaster.


    The Windows side isn't quite as easy, but it is generally possible.  If you try to use the Windows Backup utility to make a partition backup of your Windows instance on the external drive, it will work, but it will also try to do a sector copy of the MacOS partition as well, but it doesn't do that so well.  For Windows systems, I tend to use a third party tool for my backup images.  It's called Acronis True Image.  If you connect the external drive to your PC, and run Acronis True Image, it will let you create a backup clone image of the Windows 7 partition on the external drive.  Since the drive will be GPT (for MacOS) and not MBR, you may need to spring for the Plus Pack for True Image to be able to backup the volume on the external drive.  I would suggest the Plus Pack anyway, because I believe it also has the support to restore the backup image to different hardware.


    When you install Windows, it stires information about the hardware in your system, and the drivers it need to load to properly boot.  If you significantly change the hardware, Windows won't boot, and will crash loading drivers leavign you unable to boot the Windows instance.  I know that Windows XP had an installation option which was called a "repair install" which would boot from the install CD and wipe the hardware section of the registry clean, and then re-run the hardware detection phase of the install, but it would not touch the user installed software (unless it hooked into the hardware layers).  I'm sure that similar exists in Windows 7, but I haven't had to use it myself, so I'm not sure how you would use it.  I had mentioned the Plus Pack for Acronis True Image, because it assists you with this component.


    In the end, you can do what I think you are trying to do, but the Windows side isn't near as easy to do as the MacOS side. I would suggest that you consider starting the PC with a clean install of Windows 7, and user the migration tools, or just install the apps and copy the data manually...

  • mlise Level 1 Level 1 (0 points)
    Currently Being Moderated
    May 26, 2012 10:35 PM (in response to appleiser)


        You're trying way too hard in the wrong way. To Windows (including the Windows install OS) the Thunderbolt external drive appears to be an internal drive.

  • mlise Level 1 Level 1 (0 points)
    Currently Being Moderated
    May 26, 2012 10:41 PM (in response to mlise)

    Just to be really clear,







    i.e. Throw money at the problem. About $250, but it really works great. I never got an external USB drive to work, although I believe it's possible. The Thunderbolt adapter is as fast as an internal drive, so it's awesome for CAD or games or whatever.



  • gentux Calculating status...
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    Aug 15, 2012 8:21 AM (in response to appleiser)

    Windows 8 Enterprise supports Booting from USB drive. In the "old" Control Panel there will be "Windows To Go" and there you can make an external drive bootable. It will delete everything on it, but I don't see a problem opening Disk Management afterwards to shrink that partition and adding a HFS Partition there.


    Note that no earlier version of Windows supports booting from USB. And the Release Preview of Windows 8 will no longer boot after you install the Boot Camp drivers, though that's fixed in final.


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