Question How do I safely remove Dual Boot from my system setup ?

[Chedster]

Hi everyone 😊

My PC motherboard has 2 x M.2 slots. Slot M.2_1 has Windows 11 Pro on it (1TB drive). Slot M.2_2 also has Windows 11 Pro on it (500GB drive). They work perfectly in a dual boot configuration, where I can select which drive I want to boot at startup.

As I only occasionally use the second Windows installation (once a week), I want the second M.2 drive in an external USB enclosure, still being able to boot to that Windows installation when I plug it in. I have put a 4TB drive in the M.2_2 slot instead as storage.

Here is how the drives are now configured in Storage Manager in Windows (note I have typed on the right-hand side which drive is which).

This is what happens when I boot the PC now:

• When the external USB enclosure is CONNECTED, the dual boot selector appears fine on my PC. I can boot to my default Windows 11 installation just fine. But when I try to boot to the Windows installed on the M.2 drive, I see a BSOD with the following stop code: INACCESSIBLE BOOT DEVICE (photo below)
  
  
• When the external USB enclosure is DISCONNECTED, I get the “Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key” message. I cannot boot the regular Windows installation at all when the NVME enclosure is disconnected from the USB. It seems my regular Windows 11 is reliant on the other drive for booting.

I would like my PC to work like this:

• Remove the dual boot completely. Whilst the USB enclosure is disconnected, I want my regular Windows installation on the 1TB drive to just seamlessly load up.
• When I *do* want my secondary Windows to load on the USB enclosure, I'd like to be able to connect that to the USB port and have that boot first instead of the regular Windows installation within the PC.

Can anyone advise on how I can do this? I'm assuming I need to reinstall Master Boot Records or something but I am unsure and don't want to cock anything up! Any advice would be massively appreciated 🙂

Speccy Snapshot: http://speccy.piriform.com/results/XhLG61LFGVLkRCcWjujZbmY

 

[lvt]

The best way is to do a fresh Windows installation on the M2_1.

Why did your computer have the same Windows on different drives is beyond me.

 

[Chedster]

The best way is to do a fresh Windows installation on the M2_1.

Why did your computer have the same Windows on different drives is beyond me.

Thanks for your reply 👍 Wow OK, so this can only be fixed with a full reinstall? Not just a BCD Edit fix or anything?

When I was setting up my PC, I had a 'work' drive which I needed to keep completely separate from my default drive. My kids use my PC and I didn't want them installing loads of crap on my work installation, potentially downloading malware, etc. So when I work, I dual booted my work drive

 

[Math Geek]

Windows is not meant to run from a USB drive.

There is a thing called "windows to go" that can do it but that's different entirely.

Afaik you can't do what you are asking as it is now.

 

[Chedster]

Windows is not meant to run from a USB drive.

There is a thing called "windows to go" that can do it but that's different entirely.

Afaik you can't do what you are asking as it is now.

Thanks 😊 There are a few tutorials on YouTube explaining how to run Windows from external SSD or NVME drives, like this one:

View: https://youtu.be/O-R7BUTYCfU
. But that's for a fresh install. If possible, I just wanted to fix the boot records on each drive so that they can boot independently.

 

[Math Geek]

i also saw a youtube video saying the moon landing is fake, a 13900k only uses 25w of power and another one saying i can make 1 billion dollars in just 2 weeks with this one simple trick!!!

running windows from an external drive is painfully slow with a windows to go install. can't imagine a full install somehow jerry rigged onto an external. one way i have done it is to create a VM and run that from an external source. it is still painfully slow but at least it worked easy enough. was mostly a proof of concept and not something i'd ever do for real.

 

[Chedster]

Thanks for this. OK I think I'll need to rethink my plan then!

Would it be possible for me to maybe partition the new 4TB NVME drive into two separate 500GB and 3.5TB partitions (each with a drive letter) and then clone my existing 500GB drive with the secondary Windows installation onto the new 500GB partition? And then the dual boot can continue to function as it does currently, but I have the additional 3.5TB-ish for storage?

 

[SkyNetRising]

I would like my PC to work like this:

• Remove the dual boot completely. Whilst the USB enclosure is disconnected, I want my regular Windows installation on the 1TB drive to just seamlessly load up.
• When I *do* want my secondary Windows to load on the USB enclosure, I'd like to be able to connect that to the USB port and have that boot first instead of the regular Windows installation within the PC.

Can anyone advise on how I can do this?

1. Booting in windows from USB connected drive is a problem (as mentioned above). Reconsider this.

2. Only 500GB drive is bootable. It contains bootloader (100MB EFI system partition).
1TB drive is not bootable.
To make it bootable, you have to create bootloader on it.
Execute following from elevated command prompt. Regular command prompt will give error on last step.
If you get any errors, then stop immediately! And show screenshot.

diskpart​

list disk​

select disk 1​

(select 1TB disk)​

list partition​

select partition x​

(select 636MB recovery partition, x=2 or x=3. We're going to delete it next, so be careful.)​

delete partition override​

create partition efi​

format fs=fat32 quick​

assign letter=H​

exit​

bcdboot C:\windows /s H: /f:uefi​

​

Last message should be "Boot files created successfully".

Note - do not worry about recovery partition getting deleted.
After next major windows update it will be recreated.

 

[Chedster]

Many thanks for that excellent and detailed response, @SkyNetRising ! 🤗

I have found a solution which worked now, which stemmed from 'Windows To Go' being a non-starter... plus all the headaches of reconfiguring boot records, etc.

So instead, I decided instead to partition the new 4TB drive into a 500GB partition and a 3.5TB(ish) partition. I then used MiniTool Partition Wizard to clone the secondary Windows installation from the external NVME drive to the new 500GB partition.

Now the dual boot works perfectly again, as it did before, and I have a 3.5TB storage partition as well. And now I have the 500GB drive I can format and use for external NVME storage.

Thanks once again for your input guys!

 

[Math Geek]

glad you found a solution. and as always thanks for jumping in skynetrising and giving a nice detailed response