Migrate Windows 10 to an External Drive

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The focus of this document is on the process of migrating an existing Windows 10 Boot Camp partition from the internal drive to a bootable external drive using Winclone 7.

Storage and Migration Scenarios for Windows 10 using Winclone 7

  • Migrate Boot Camp from internal to external bootable drive
  • Run multiple bootable Windows 10 partitions on internal Intel Mac drive
  • Run multiple bootable Windows 10 partitions on external drive attached to Intel Mac
  • Migrate Windows 10 from a PC to Intel Mac
  • Migrate Windows 10 from Boot Camp to a PC that supports EFI mode
  • Create Winclone image of a Windows 10 PC drive
  • Restore a Windows 10 Winclone image to a PC drive for use in a PC that supports EFI mode


In order to move your Bootcamp partition from your Mac to an external drive, it must meet the following requirements:

  1. Intel Based Mac with EFI version 2 or greater (see http://support.apple.com/kb/HT1237)
  2. USB or Thunderbolt external drive (USB flash drives not supported)
  3. Bootcamp partition with Windows 10 or later

All procedures outlined have been tested on Windows 10 1803 (October Update).

The following Mac models were tested with the procedure:

  • MacBook Pro (2018)
  • MacBook Air (13-inch, Mid 2011), 10.13.5, MacBook Air 4,2
  • Mac Mini (Mid 2014)
  • iMac (27-inch, Late 2012), 10.14, iMac 13,2
  • Mac Mini (Mid 2011), 10.13.4, Mac Mini 5,1 (legacy)
  • MacBook (12-inch, Early 2015)
  • MacBook Air (13-inch, Mid 2011), 10.13.5 (legacy)
  • iMac (Retina 5k, 27”, Late 2015), 10.13.6, iMac 17,1

The following external USB-C hard drives where used:

Both external SSD were connected via a USB-C to USB-C cable, or USB-C to USB-A depending on ports available on the Mac.

Prepare External Drive in macOS using Disk Utility

Before migrating Windows 10 Boot Camp to a bootable external drive, the drive must be formatted with the GUID partition scheme and partitioned with an ExFAT partition.  Keep in mind that this process will erase all existing data on the external drive, so make sure to back up any critical data elsewhere before proceeding.

Attach the external drive and open Disk Utility in the Utilities folder.

Select the external drive in the left side column.  At the bottom of the Disk Utility window will be information about the disk.  If the Partition Map is already set as “GUID Partition Table” you may skip to the section below “Add Partition.”

Create GUID Partition Table

Under the view menu in Disk Utility, select “Show All Devices”

  1. Make sure the external drive (and not the volume) is selected.
  2. Click the erase button in the toolbar. If you do not see the Scheme option, verify that the disk is selected in the left hand column and not a partition.
  3. Give the volume a name, format as ExFAT (this will be changed during migration to NTFS), and GUID Partition Map for Scheme.


Add Partition

After the disk has a GUID Partition table, you can leave it as a single ExFAT partition or add other partitions. If the external drive has a Mac (HFS+) partition, you can use Disk Utility to create a ExFAT partition from some of the free space from the Mac partition. To do so:

  1. Select the Mac Partition and click “+”
  2. Drag the size handle to make the size you want
  3. Give the partition a name and select ExFAT as the Format.

A Note About File System Formats

The partition on the external drive was created as ExFAT because Disk Utility cannot natively create NTFS formatted partitions. Winclone can select destinations as ExFAT and will overwrite the ExFAT format during the migration and the result will be an NTFS formatted Windows file system.

Prepare the Boot Camp Partition

To successfully migrate the Boot Camp partition from the internal volume to an external volume, it is recommended that you prepare Windows with Sysprep prior to booting to the migrated copy of Windows on the external drive. Since Sysprep can fail and leave the Windows install in an unknown state, it is also recommended that you create a Winclone image of the Windows install on the internal partition prior to running Sysprep. Alternatively, you can run Sysprep after restore from the external volume in a Virtual Machine such as VMware Fusion.

To run Sysprep on the internal volume, see this article.

Migration with Winclone

Once the partition has been created in Disk Utility, quit out of Disk Utility.  Verify that the newly created partition is visible as a mounted volume on the Mac desktop.  Open Winclone and select Volume to Volume Cloning. Select the following options:

  1. Select source volume as the internal Boot Camp partition.
  2. Select the destination as the ExFAT volume you created on the external volume.
  3. Click Clone.

If you get a error message about a block size mismatch, create a Winclone image and then restore the image to the external volume. See the articles below for creating and restoring a Winclone image:

Create Image from Volume

Restore Image

Run Sysprep in a VM

If you did not run Sysprep prior to creating the image, you can run Sysprep in a Virtual Machine such as VMware Fusion. See the article here.

Booting into Windows

Once the migration process is complete, restart while holding Option (⌥). The new external Boot Camp volume will be available for startup.

Tested Hardware

External booting was verified by the following process:

  1. Windows 10 (1809 October Update) was installed via Boot Camp Assistant.
  2. The Mac was booted into Windows 10, and Boot Camp drivers for that model were installed.
  3. After the reboot required after Boot Camp drivers were installed, Sysprep was run and Windows shut down.
  4. The Mac was booted into macOS and Winclone 7 installed and launched.
  5. An ExFAT partition was created on the external drive (GUID partition table).
  6. Boot Camp was migrated to the external partition using the Volume to Volume feature of Winclone 7. If a block size message was shown, a file-based image was created and the image was restored to the external partition.
  7. Using Disk Utility, the Boot Camp partition was deleted from the internal drive.
  8. The Mac was then booted to Windows on the external volume and verified to work.