[SOLVED] Confusing situation with HDDs and Windows 10

[aetran]

Hey guys, I've gotten myself into an extremely confusing situation and I hope someone can help me unravel this.

A year or so ago I bought a new HDD and migrated my windows 10 installation to it. It's split into C (for windows and general use) and G (mostly for games and other large files I don't usually need to directly access).

I wiped my old disk clean and have been using it as tertiary storage (E), expecting it to eventually die on me.
Recently my computer has been giving me the store exception BSOD, but to my suprise my main disk is completely fine, it's only E that's dying, as expected. Taking it out prevents my computer from booting too, so I doubled checked which was my boot drive and according to disk management partition C is for boot and E is for system files; however all of my system files are on C, where I had installed windows, if I look for them myself. E has none hidden or visible besides windows crash dumps.
I'm extremely confused as to how this even happened, let alone how to fix it. An easy solution would be a clean install, but without an external HDD and with too many scattered files and saves and stuff, as well as several terabytes of stuff I'd prefer to not have to reinstall a second time, I'm wondering if there's any other way to solve this problem and possibly direct windows to my preexisting installation.

 

[Darkbreeze]

Your hidden boot partition is likely still on the E: drive, and removing that drive removes the boot partition that the UEFI BIOS looks for when attempting to boot the machine. You are not going to see it through normal programs and in disk management it likely shows as a system or hidden partition. To be clear, these are not "Windows" files, they are the Windows boot manager, which is never contained in the same partition as the rest of Windows in Windows 10 or other UEFI installations.

Please take a screenshot of your disk management window showing all attached drives and their partitions and post it here.

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[aetran]

Here's all of my partitions

 

[SkyNetRising]

You have a bootloader on partition E: .
To make 3TB drive bootable, you have to fix bootloader on it.
Execute from elevated command prompt, regular command will give error on last step:
(https://www.bleepingcomputer.com/tutorials/how-to-open-a-windows-10-elevated-command-prompt/)

diskpart​

list disk​

select disk 0​

list partition​

select partition 1​

(select 100MB System Reserved partition)​

active​

assign letter=H​

exit​

bcdboot c:\windows /s H:​

Now boot into BIOS and change boot priority, so 3TB drive is first in boot order. Should be able to boot into windows. System Reserved partition should be listed as "System, Active, Primary Partition" now.

 

[SkyNetRising]

After this is done, you can deactivate bootloader on E:
(do this only, if you have successfully booted from 3TB drive and have verified, that System reserved partition reads as "System, Active, Primary Partition" or else you'll make your pc unbootable)

diskpart​

list disk​

select disk 1​

list partition​

select partition 1​

(select 465GB partition)​

inactive​

 

[aetran]

When trying to set partition 1 as active, it tells me that the disk isn't a fixed MBR disk. From what I understand, this would require formatting the disk, no?

 

[SkyNetRising]

When trying to set partition 1 as active, it tells me that the disk isn't a fixed MBR disk.

Can you show a screenshot?
It's possible partition 1 already is active (can't see that in your previous screenshot).

 

[aetran]

According to disk manager it's not active, just a primary partition.
Here's the CMD

 

[SkyNetRising]

Oh right. Your 3TB disk is GPT partitioned.
Your system must support UEFI boot to be able to boot from GPT partitioned drive.
What's the motherboard model name?

If your system supports UEFI, then you can make 3TB drive bootable this way:
(execute from elevated command prompt)

diskpart​

list disk​

select disk 0​

list partition​

select partition 1​

(select 100MB partition)​

delete partition override​

create partition efi​

format fs=fat32 quick​

assign letter=H​

exit​

bcdboot c:\windows /s H:​

​

In BIOS enable UEFI boot and set first boot device to Windows Boot Manager.

 

[aetran]

That worked, kinda. Now I'm just met with a shell. I'd assume this is because my OS is in legacy.

 

[SkyNetRising]

Did you set windows boot manager as first boot device?

It's possible boot configuration was not set properly for UEFI.
Boot from 500GB drive and try this from elevated command prompt:

bcdboot c:\windows /s H: /f UEFI​

 

[aetran]

Oh yeah, I forgot to give you my model. It's an MSI H81M-P33
I don't have an option to set that as a boot device. In UEFI it's just a bunch of generic, possible UEFI boot devices like hard disks, USB, and network.

 

[aetran]

Hmm, when I try using the command above I get "failure when initializing library system volume"

 

[SkyNetRising]

Can you show current screenshot from Disk Management?

 

[aetran]

Here you go
I set the letter of disk 0 partition 1 to H:, but it doesn't seem to reflect that on Disk Management.

 

[SkyNetRising]

Doesn't seem like letter H: is set up properly.

 

[aetran]

Not entirely sure what went wrong the first time as everything went through, but I repeated the process again, and this time it said H was taken so I chose I, and it seems like it worked! Thanks a ton man, you saved me a lot of potential hassle and tought me a bunch too.

 

[chiefkiks]

I know it's years later but I just need to say thank you to you both for this thread. I'd been struggling with this issue for hours going round in circles, but finally managed to solve a similar issue I was having by creating the UEFI partition with the technique that you guys discussed