I made the mistake of purchasing a MBP w/ only 128 GB of storage. When I ran out of space on the internal drive, I purchased a 512 GB external SSD, transferred all the data over to the SSD, and now run El Capitan on the external drive and use it as my main startup drive (in fact, the internal drive is completely formatted).

How do I partition the external SSD into two drives, one that runs OS X and the other with Windows 10? The reason I don't want to set up windows on the internal drive is because I want 256 GB dedicated to windows, leaving the other 256 GB on the external drive for OS X.

Boot Camp Assistant seems to only detect the internal drive, so I don't know how to properly partition the drive and install windows 10 on it. I've tried partitioning with Disk Utility as well, but when running Boot Camp again, it only allows me to partition the internal drive. Maybe there is a way to install Windows on the internal drive, and then transfer it over to a 256 GB partition on the external drive?

I'm very new to/unfamiliar with this kind of stuff, so I'm sorry if this is a poor question.

Thanks for your help


3 Answers 3


As Apple states here: https://support.apple.com/en-us/HT201456

Can I install Windows on an external drive?

No, Boot Camp requires that Windows be installed on your internal hard disk.

There's a workaround, which doesn't use Bootcamp. Personally, I haven't tried it. http://bleeptobleep.blogspot.gr/2013/02/mac-install-windows-7-or-8-on-external.html


Don't stress yourself out over this. Use a VM platform like VirtualBox (free) or Parallels (not free) and you can run a VM from any drive.

Here is a screenshot of my iMac with OS X El Capitan running both a Window 7 and Windows 10 VM and what you are not seeing is the headless FreeBSD 10.2 Development server also running but can be seeing running in the VBox Console. It's super easy and since going this way, I have never needed to resort to Boot Camp (disclaimer: I don't game)

enter image description here

Links to the VM Software websites:




Try parallels, it lets you run multiple OS

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