Windows, external disk: Why not this way?

[J.Gallardo]

I'm using a 2017 5K iMac, 1Tb internal SSD. I'd like to have a Bootcamp partition, but would not make it in my internal SSD. (I want that thing out and jailed
I've read about some ways to do it, but they imply some fiddling and using additional software.
I'm thinking about a simpler solution:
- cloning my essential system and making an external start-up disk (I mean cloning my internal disk -except big contents folders- and deleting big & unneeded apps afterwards).
- starting my iMac from external disk... AND making a Bootcamp installation when "being there"

After this, I suppose that holding "alt" at start up, I should be able to choose internal disk, OR external disk, OR Windows partition...
OR do I miss something important? Does Mojave reject to make a BootCamp partition if running on external disk? Always, or does it depend on interface used?
I don't mind losing the space needed for Mac OS on the external SSD if I could make Windows work this way.
(The "tricky" way is so very well explained in so many places -this forum included- that I suspect I'm wrong, but couldn't find info about this, and macs are supposed to behave the usual way when running on external disk, so...?). It'll be ok if I have to follow known way at the end, but I had to ask.
Thanks for reading.

 

[casperes1996]

OR do I miss something important? Does Mojave reject to make a BootCamp partition if running on external disk? Always, or does it depend on interface used?

From what I've heard (not experience) it'll reject it when it's external, no matter if you clone the Mac OS system to the extenral or not. It'll realise it's an external interface and say no-go. From what I've gathered it comes down to Microsoft considering external Windows installations unsupported, so Apple decided to follow Microsoft's policy on the matter, even though it's technically possible.
macOS and Linux and basically all Unix systems don't care so much where they're stored

 

[hfg]

I also have a 2017 iMac but with a 2TB SSD and had initially used BootCamp to create a 250GB Windows 10 partition on the SSD. I use it booted natively and as a VM using VmWare Fusion. I also have WinClone which I use to keep a backup image for the Windows installation.

Just a few days ago, I made an external Windows SSD using a Samsung T5 500GB USB SSD. I formatted it as ExFat and used WinClone to load my saved Windows image on on the external T5 SSD. All seemed fine, but it would not boot showing an error: "Inaccessable_Boot_Device". A little research on the TwoCanoes WinClone website revealed several ways to deal with this. What worked for me was creating a new VM from the external Windows SSD (which I wanted anyway), then using RegEdit to patch the boot_device for USB. It now works fine, boots fine, runs as a VM fine ... so it was a success!

It is not quite as fast as the internal SSD Windows, but that is barely noticeable in real use. Now I am pondering which to keep in use since an external drive, even a small T5, kind of ruins the clean look of the all-in-one iMac. But, I have always liked the idea of Windows on a separate drive from OS X, and that would also free up the entire internal SSD for OS X and photos.

Good luck doing yours ....

EDIT: I have done this several times in the past on iMacs, MacPro, Mac Minis using WinClone without any problems at all ... just a simple WinClone image install to the external disk. I don't know why I needed the RegEdit patch this time unless it has something to do with Mojave/WinClone which hasn't been worked out yet.

 

[J.Gallardo]

I also have a 2017 iMac but with a 2TB SSD and had initially used BootCamp to create a 250GB Windows 10 partition on the SSD. I use it booted natively and as a VM using VmWare Fusion. I also have WinClone which I use to keep a backup image for the Windows installation.

Just a few days ago, I made an external Windows SSD using a Samsung T5 500GB USB SSD. I formatted it as ExFat and used WinClone to load my saved Windows image on on the external T5 SSD. All seemed fine, but it would not boot showing an error: "Inaccessable_Boot_Device". A little research on the TwoCanoes WinClone website revealed several ways to deal with this. What worked for me was creating a new VM from the external Windows SSD (which I wanted anyway), then using RegEdit to patch the boot_device for USB. It now works fine, boots fine, runs as a VM fine ... so it was a success!

It is not quite as fast as the internal SSD Windows, but that is barely noticeable in real use. Now I am pondering which to keep in use since an external drive, even a small T5, kind of ruins the clean look of the all-in-one iMac. But, I have always liked the idea of Windows on a separate drive from OS X, and that would also free up the entire internal SSD for OS X and photos.

Good luck doing yours ....

Thank you for sharing your experience. I see going VmWare or/and Terminal seems the way. I've read some after my opening post, and -of course- doing like I thought is impossible, as Bootcamp is designed to work just on internal disk.
Still with the doubt about interfaces (perhaps somebody knows):
Could an external SSD be considered as internal by OS, as it uses PCI lanes when on Thunderbolt?
Everything said about Bootcamp on external SSDs ignores Thunderbolt, or maybe it's just the same. I would like to know.
Thank you.

 

[hfg]

Actually, this is my first attempt at an external USB-connected Windows installation due to the fact that I wanted to use the T5 SSD and it is only available as a USB drive. All of my previous external Windows installations were on Thunderbolt SSDs, with the exception of my cMacPro which is on a PCI bus card SSD. I usually used LaCie "Rugged" Thunderbolt enclosures purchased as refurbished hard drives, and then swapped out the HD for the SSD.

Unfortunately, the Thunderbolt drives are also considered "external" and thus can't be directly installed using the BootCamp utility application. I again installed Windows internally, then used WinClone to make my external bootable Windows SSD, then deleted the internal partition to reclaim the internal disk space.



EDIT-2:

Just for fun, I just spent the past 15 minutes creating a Thunderbolt SSD Windows installation using WinClone and the previously created Windows image file.

I used a spare Crucial M4 500GB SSD on a Seagate "GoFlex Thunderbolt Adapter" and an Apple TB3-->TB2 adapter cable to the 2017 iMac 27". It booted up without any problems and seems to be running fine. All the applications I had installed were there and seemed to run fine.

I have been using WinClone for several years now and am pretty happy with it. Not only can I move Windows to different drives, but I use it routinely to create a back-up image of my Windows installation using OS X so that I can easily replace my running install if something should happen to it.

 

[J.Gallardo]

I again installed Windows internally, then used WinClone to make my external bootable Windows SSD, then deleted the internal partition to reclaim the internal disk space

That seems pretty clean & forward procedure. I understand first time you found problems has been turning to USB... And suppose Thunderbolt has something different that made "just porting with WinClone" enough to make a bootable win ssd...
It seems USB is not so direct. (I think I've read something about this: Microsoft forbids to run Windows from external disks, -it's not Apple to blame- but "thunderbolt gate" is not closed... Or something like that...).
Thank you!!!

 

[SaSaSushi]

Yeah, I can confirm that even Thunderbolt external drives cannot be installed to directly with BootCamp but Windows itself has none of the issues on Thunderbolt that are associated with USB external drives.

I restored a WinClone image to the SSD in my Delock Thunderbolt enclosure a few years ago and it has been running perfectly and error-free since then.

I can also upgrade SSD firmware and use TRIM with no issues.