Cloning an external Boot Camp SSD

I have migrated my Boot Camp partition onto an external SSD.
It works well.
As a safety I would like to clone this external SSD onto a second external bootable disk.
What is the procedure to follow ?

The easiest way would be to create a Winclone image of the SSD and then restore it on the 2nd SSD.

BTW, what make/model was the external SSD?


This is what I did.
But when I tried to restore the Winclone image to the 2nd SSD (formatted NFTS, same size) I got a Winclone alert : "Invalid Partition Type. The partition type is not GPT. Winclone requires a GPT partition type."
How can I create a GPT partition on my 2nd SSD ?

I forgot to say :slight_smile:slight_smile:

  • I created the Winclone image on a external 1GB SATA disk
  • The 2nd disk is a 1GB USB 3.0 disk


When you partition the disk in Disk Utility, you select the drive (not a volume) and click Erase. You then have an option to select GPT as the disk partition type.


I erased the 1GB USB 3.0 disk with Disk Utility.
We have several choices : I chose Format = ExFAT and Scheme = GUID Partition Map
Is this correct ?
Then I disabled the Mac SIP with Terminal and restarted.
This time we went a step further with Winclone.
But I got the error :
ERROR : Copying BCD failed. See the system log for more information
I dont see a way of attaching the system log.

I tried again and again. There is no way to select GPT as the disk partition type in Disk Utility.
Could you please explain step by step:

  • how I should format my disk and with what software,
  • if I should disable the Mac SIP before,
  • if I have to use the Winclone menu Tools > Make EFI Bootable

you did it correctly. GUID Partition Map is GPT. I think you are hitting another issue, which is a difference in block size between the two drives:

To work around this, you create the image in WIM mode (you can set this in Preferences). Then you should be able to restore that image to the new volume.


Thanks : it works now beautifully (I can directly boot from the image)

I wrote that for myself :
28-07-17 : Use of Winclone to create a bootable Win10 SSD Backup disk
After multiple exchanges with :

  • With Disk Utility : Format the receiver disk : Format = ExFAT, Scheme = GUID Partition Map
  • With Terminal : Restart on Mac from the Recovery partition and Disable Mac SIP : csrutil disable
  • With Winclone : 1/ in Preferences > Ask to update boot configuration data (BCD), 2/ in dialog click on Replace BCD File, 3/ Restore to Volume
  • With Terminal : Restart on Mac from the Recovery partition and Enable Mac SIP : csrutil enable

The history behind BCD is that Apple changed the disk format starting in 2015 and my two Macs are late 2014 and mid 2014
See Winclone Image Compatibility with 512 and 4K Block Size on 2015 MacBooks : “Winclone images created on pre-2015 Mac hardware will boot on other pre-2015 Mac hardware.”

Thanks for posting the result!


jc2249: Thank you so much for this. It is very useful. tperfitt, could you tell me if this same procedure will work with a W7 partition as below?

I have a High Sierra SSD with a 300GB W7 bootcamp partition that I am currently using as an external drive because I upgraded my computer. I have now purchased a new 1TB external SSD that I would like to use as a bootable windows external disk. I want to transfer the W7 partition on the High Sierra SSD to the new SSD.


If you mean W7==Windows 7, then it probably will not. Windows 7 has issues booting EFI on Macs.


OK. I have decided to upgrade the source disk to Windows 10.

Good luck and let me know how it turns out!