Thinking of running Windows on a Mac? You can choose Boot Camp or a virtual machine, but are hidden costs in performance for both options. You might be surprised to find which one is faster.
I’ve been using a late 2013 Retina Macbook Pro as my primary computer for almost two years. It meets all my needs in my day job and is light enough to carry everywhere even while flying around for work.
While I love the time flying affords to switch offline and catch up on some well deserved gaming, mobile gaming can be bit bland and Mac OS X doesn’t run my favourite games like Skyrim without some fairly unreliable and poorly performing hacks via Wine.
But what about Bootcamp? I was in a very limited place, the 256GB SSD quickly fills up and I couldn’t spare the space to partition and install Bootcamp Apple’s way.
Enter the Samsung Portable SSD T1, this speedy little drive is small enough to hang off the side of my Macbook without getting in the way and a bump or two won’t damage it.
Unfortunately Windows refuses to install to any USB based storage which has historically been far too slow to run a fully fledged operating system.
But that’s no issue for the T1 which by Samsung’s own estimates can reach up to 450MB/s. It’s more than fast enough to run Windows as if it were running directly on the internal drive.
Luckily with the power of virtualisation it’s easy to bypass these pesky limitations and get Bootcamp running entirely off the external USB SSD drive without making any changes to the internal SSD.
Read on to find out how!
What you’ll need:
You’ll need a few things to complete this guide:
- A Mac which supports booting from a USB Device (see Apple Support: Mac computers that support Windows 10)
- A USB 3.0 SSD similar to the Samsung T1 (a flash storage device will not be fast enough)
- A spare USB drive with a minimum of 2GB of storage to copy the Bootcamp Drivers over to Windows.
- Basic understanding of VirtualBox and installing Windows.
Download Windows 10 Installation
Windows 10 is available to download from Microsoft and allows a grace period to license the installation. Windows 10 can be purchased from the Microsoft Store.
Follow the prompts to download Windows 10 installation disk.
The download is 3.7GB so it may take some time, the next steps will prepare your system to install Windows 10 to the USB SSD.
Download Bootcamp Software for Windows 10
Apple offer a prepackaged driver installation for Bootcamp.
Thanks to Reddit user sadalhayat for identifying this link.
Once this has downloaded copy it to a spare USB drive separate from SSD you will be using to install Bootcamp. Save this for later.
![Mac Mac](/uploads/1/2/5/8/125837731/850501932.jpg)
Mac OS X cannot write to the Windows drive out of the box. For this reason you will need to use a separate drive to copy the Bootcamp Software into the new Bootcamp Installation.
Install VirtualBox
Are you wondering why VirtualBox is the next step? Don’t worry, we’re taking advantage of the virtualisation technology to kick start the installation of Windows 10.
We will be using VirtualBox to mount the USB drive as a virtual hard disk inside the Virtual Machine. This bypasses the limitations imposed by the Microsoft Installer preventing us from installing Bootcamp the Apple way.
Download and Install VirtualBox
If you don’t already have VirtualBox, it can be downloaded from their website. Once you have downloaded the package, use the installation package to get up and running with VirtualBox.
Identify your USB Drive’s device location
Open up the Terminal and type:
This command will list all the connected drives on your computer. Browse through the list until you find your storage device.
The text highlighted red “/dev/disk2” is the information we need. This information will tell VirtualBox exactly which storage device it needs to access.
Please note this information may be different on your machine. Read the list carefully to match the address of your USB SSD.
Disconnecting Mac OS X from the USB SSD.
Before we connect VirtualBox to our USB SSD you will need to completely unmount the SSD from Mac OS X to allow VirtualBox full access to the USB SSD.
This can be done by searching for Disk Utility in Spotlight then
- Choosing the External USB Device
- Choosing Eject in the top Menu
Create a Virtual Disk mapping to the USB Drive
This is where the magic starts. We will be using VirtualBox to mount the USB SSD as a normal hard disk in order to trick the Windows 10 installer into thinking it is using a normal hard drive.
First we need to create a Virtual Disk File for VirtualBox so it knows what storage device we are accessing.
Below is the command we will be modifying to create the Virtual Disk file
You can copy the entire command with the exception of the last part “/dev/diskX” which will need to be changed to the drive number you identified in the previous step.
In my case it is “/dev/disk2”.
Installing Windows 10 to the USB SSD via VirtualBox
Now that we have everything organised we can start the installation of Windows 10 via VirtualBox.
We will need to give VirtualBox elevated permissions to access our handy bootcamp.vmdk file.
In your terminal type:
![Run Run](/uploads/1/2/5/8/125837731/293682282.jpg)
This will force VirtualBox to run as the root user and have permission to access the USB SSD.
Creating Virtual Machine
In VirtualBox choose “New” and type “Windows 10 Bootcamp” and click Continue.
Change Memory to “512” MB and click Continue.
On the Hard Disk screen choose “Use an existing virtual hard disk file” browse to your home directory and select the newly created “bootstrap.vmdk”.
Installing Bootcamp, from a Virtual Machine
Now that we have scaffolded the Virtual Machine, connected the hard drive and downloaded Windows 10, it is time to install Windows 10 onto our shiny new USB SSD.
Back in VirtualBox we will need to mount the Windows 10 Installation ISO into the virtual DVD drive.
- Open the Virtual Machine’s Settings Panel.
- Select the Storage tab on the top of the Settings Panel.
- Select the Empty DVD Icon.
- Select the CD Icon next to the Optical Drive, Choose Virtual Optical Disk File and select the Windows 10 ISO file.
- Select OK to save the new settings.
Run the Normal Windows 10 Installation
Follow through the standard screens to begin the Windows 10 installation.
Clicking next and agreeing to the terms and conditions is all you really need to do here except for the following points:
When you meet the installation type screen, select “Custom”.
When you are asked where to install Windows, just delete any existing partitions and select “Next”.
Don’t worry, Windows can only see the USB SSD drive you assigned by VirtualBox, your Mac’s existing partitions are not accessible here.
Important! Don’t let windows restart!
This is the most crucial step to successfully installing Bootcamp on an external USB 3.0 SSD
When Windows 10 is restarting, make sure you prevent Windows restarting inside the Virtual Machine and completing the installation.
- When you see the VirtualBox BIOS screen select the Red Close Button
- Choose “Power off the machine”.
- Choose OK to power off the Virtual Machine.
That’s enough Virtualisation!
Now that we’ve completed the first phase of the Windows 10 installation, we don’t need to use VirtualBox anymore.
This completes all the steps required on the Mac OS X side of the installation.
Reboot your Mac into Windows
It’s now time to restart your Mac and boot into Windows 10. Power off your Mac and hold the Option key until disk icons appear onscreen.
Let Windows 10 install
If everything went well Windows 10 should start booting and begin the initial installation.
Just follow through the screens and fill in your details as required.
Windows 10 may reboot during the installation. If this occurs, make sure you press the Option Key and select the Boot Camp Drive to continue the installation.
Install Bootcamp Software
Plug in the spare USB Drive we copied the Bootcamp Software to earlier and run “AppleBCUpdate.exe”.
This will start the Bootcamp installation software to install drivers for the Apple Keyboard and Mouse, Wireless, Graphics and other devices in your system.
That’s it!
If everything went according to plan you should now be able to boot directly into Windows 10 whenever the USB SSD is connected to your computer!
My experience has been rock solid, and I can enjoy all the benefits of running Bootcamp on my Mac to run Windows Applications and Games without sacrificing the valuable storage space of the internal SSD.
Did you find this article helpful? Let me know in the comments section below!
Keep in mind Microsoft and Apple never intended for you to run Bootcamp this way. Make sure you never disconnect the USB SSD from your system while Windows is running!
What you need to install Windows 10 on Mac
- MacBook introduced in 2015 or later
- MacBook Air introduced in 2012 or later
- MacBook Pro introduced in 2012 or later
- Mac mini introduced in 2012 or later
- iMac introduced in 2012 or later1
- iMac Pro (all models)
- Mac Pro introduced in 2013
The latest macOS updates, which can include updates to Boot Camp Assistant. You will use Boot Camp Assistant to install Windows 10.
64GB or more free storage space on your Mac startup disk:
- You can have as little as 64GB of free storage space, but at least 128GB of free storage space provides the best experience. Automatic Windows updates require that much space or more.
- If your Mac has 128GB of memory (RAM) or more, the Windows installer needs at least as much free storage space as your Mac has memory. For example, if your Mac has 256GB of memory, your startup disk must have at least 256GB of free storage space for Windows.
An external USB flash drive with a storage capacity of 16GB or more, unless you're using a Mac that doesn't need a flash drive to install Windows.
A 64-bit version of Windows 10 Home or Windows 10 Pro on a disk image (ISO) or other installation media:
- If installing Windows on your Mac for the first time, use a full version of Windows, not an upgrade.
- If your copy of Windows came on a USB flash drive, or you have a Windows product key and no installation disc, download a Windows 10 disk image from Microsoft.
- If your copy of Windows came on a DVD, you might need to create a disk image of that DVD.
How to install Windows 10 on Mac
To install Windows, use Boot Camp Assistant. It's in the Utilities folder of your Applications folder.
1. Use Boot Camp Assistant to create a Windows partition
Open Boot Camp Assistant and follow the onscreen instructions:
- If you're asked to insert a USB drive, plug your USB flash drive into your Mac. Boot Camp Assistant will use it to create a bootable USB drive for Windows installation.
- When Boot Camp Assistant asks you to set the size of the Windows partition, remember the minimum storage-space requirements in the previous section. Set a partition size that meets your needs, because you can't change its size later.
2. Format the Windows (BOOTCAMP) partition
When Boot Camp Assistant finishes, your Mac restarts to the Windows installer. If the installer asks where to install Windows, select the BOOTCAMP partition and click Format. In most cases, the installer selects and formats the BOOTCAMP partition automatically.
3. Install Windows
Unplug any external devices, such as additional displays and drives, that aren't necessary during installation. Then click Next and follow the onscreen instructions to begin installing Windows.
4. Use the Boot Camp installer in Windows
After Windows installation completes, your Mac starts up in Windows and opens a ”Welcome to the Boot Camp installer” window. Follow the onscreen instructions to install Boot Camp, including Windows support software (drivers). You will be asked to restart when done.
If the Boot Camp installer doesn't open automatically, your final step should be to open the Boot Camp installer manually and use it to complete installation.
How to switch between Windows and macOS
Restart, then press and hold the Option (or Alt) ⌥ key during startup to switch between Windows and macOS.
Learn more
If you have one of these Mac models using OS X El Capitan 10.11 or later, you don't need a USB flash drive to install Windows:
- MacBook introduced in 2015 or later
- MacBook Air introduced in 2015 or later2
- MacBook Pro introduced in 2015 or later2
- iMac introduced in 2015 or later
- iMac Pro (all models)
- Mac Pro introduced in late 2013
For more information about using Windows on your Mac, open Boot Camp Assistant and click the Open Boot Camp Help button.
1. If you're installing Windows and macOS Mojave on an iMac (27-inch, Late 2012), iMac (27-inch, Late 2013), or iMac (Retina 5K, 27-inch, Late 2014) and your Mac is configured with a 3TB hard drive, learn about an alert you might see during installation.
2. These Mac models were offered with 128GB hard drives as an option. Apple recommends 256GB or larger hard drives so that you can create a Boot Camp partition of at least 128GB.