Solved Why does Windows allocate 100MB to the other disk


FirasKing Air

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Why does Windows allocate 100MB to the other disk even when I intentionally left it unallocated? Will Windows still boot if I lose that 100MB?

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It looks like Windows was installed on Disk #2 previously and when you installed Windows on Disk #1, it used this FAT 32 partition for the boot files.
You can test this theory by unplugging Disk #2 and starting the computer. If it loads Windows on Disk #1, then you can safely delete that Partition on Disk#2.
 

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Windows has been known to stick that EFI system partition on any disk it feels like during installation.
The safe way to install Windows includes removing all other disks before you start.

If that is a Disk management diagram then check the partitions in, say, MiniTool partition wizard.
If, as I think, it is a MiniTool partition wizard diagram {and hence an accurate diagram} then you have a problem to resolve [unless, of course, you have deliberately been removing partitions yourself but then you would not be asking this question].

I think the most straightforward method of removing that partition involves all these steps:-
1 Make a new system image of your Windows disk [disk 1].
2 Disconnect disks 2 & 3.
3 Clean install Windows on disk 1.
4 Restore the C:\ drive of the system image to the C:\ drive of disk 1.
5 Reconnect disks 2 & 3 if you want them connected.
6 Delete that 100MB partition from disk 2.
7 Make a new system image.
It's quite a bit of work.

I'm surprised to see that disk 3 is MBR even though the others are GPT.
I'm also surprised that it is so small. Oh, its icon might mean it's some sort of floppy drive.
Perhaps it would be worth resolving that afterwards.


All the best,
Denis
 

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Windows has been known to stick that EFI system partition on any disk it feels like during installation.
The safe way to install Windows includes removing all other disks before you start.

If that is a Disk management diagram then check the partitions in, say, MiniTool partition wizard.
If, as I think, it is a MiniTool partition wizard diagram {and hence an accurate diagram} then you have a problem to resolve [unless, of course, you have deliberately been removing partitions yourself but then you would not be asking this question].

I think the most straightforward method of removing that partition involves all these steps:-
1 Make a new system image of your Windows disk [disk 1].
2 Disconnect disks 2 & 3.
3 Clean install Windows on disk 1.
4 Restore the C:\ drive of the system image to the C:\ drive of disk 1.
5 Reconnect disks 2 & 3.
6 Delete that 100MB partition from disk 2.
7 Make a new system image.
It's quite a bit of work.


All the best,
Denis
Thank you Sir

and yes it is MiniTool partition wizard diagram
keeping it for now, I wrote down the steps you provided. Although I know removing all disks is the best way, I wanted to see if it would still install on an unallocated disk.
:thumbsup:
 

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My Desktop from April 2022, came with 512GB NVMe drive and added the 2TB HDD later using power and data cables already in the case..

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If you want you can delete the EFI partition on Disk 2 and create a new EFI partition on Disk 1.

In this video, i will show you how to create EFI partition from within Windows Recovery Environment.

 

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I wrote down the steps you provided
And do remember that my solution was what I regarded as straightforward.
Solutions, such as Freebooter's, to delete-create-populate partitions manually are a lot quicker but I found them complicated when I tried them several years ago.
As long as you precede everything with a system image then you can try such solutions.


Denis
 

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Windows 11 Home x64 Version 25H2 Build 26200....
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If you want you can delete the EFI partition on Disk 2 and create a new EFI partition on Disk 1.

In this video, i will show you how to create EFI partition from within Windows Recovery Environment.

I greatly appreciate your help. The information you provided is exactly what I needed. Thank you!
many thanks :thumbsup: ;-);-)
 

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I greatly appreciate your help. The information you provided is exactly what I needed. Thank you!
many thanks :thumbsup: ;-);-)
You are very welcome!
 

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Windows 11AMD Ryzen 7 5700GMicron Technology DDR4-3200 16GBNVIDIA GeForce RTX 3060
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HP Pavilion
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AMD Ryzen 7 5700G
Motherboard
Erica6
Memory
Micron Technology DDR4-3200 16GB
Graphics Card(s)
NVIDIA GeForce RTX 3060
Sound Card
Realtek ALC671
Monitor(s) Displays
Samsung SyncMaster U28E590
Screen Resolution
3840 x 2160
Hard Drives
SAMSUNG MZVLQ1T0HALB-000H1
Windows has been known to stick that EFI system partition on any disk it feels like during installation.
The safe way to install Windows includes removing all other disks before you start.

If that is a Disk management diagram then check the partitions in, say, MiniTool partition wizard.
If, as I think, it is a MiniTool partition wizard diagram {and hence an accurate diagram} then you have a problem to resolve [unless, of course, you have deliberately been removing partitions yourself but then you would not be asking this question].

I think the most straightforward method of removing that partition involves all these steps:-
1 Make a new system image of your Windows disk [disk 1].
2 Disconnect disks 2 & 3.
3 Clean install Windows on disk 1.
4 Restore the C:\ drive of the system image to the C:\ drive of disk 1.
5 Reconnect disks 2 & 3 if you want them connected.
6 Delete that 100MB partition from disk 2.
7 Make a new system image.
It's quite a bit of work.

I'm surprised to see that disk 3 is MBR even though the others are GPT.
I'm also surprised that it is so small. Oh, its icon might mean it's some sort of floppy drive.
Perhaps it would be worth resolving that afterwards.


All the best,
Denis
I once had a problem with a system that I dual booted from two HDDs. When I removed the second drive my computer wouldn't boot. Nothing I tried worked and that included using Macrium to create the boot partition. In the end I fixed the problem by doing steps 1 - 4 of what you posted.
 

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I once had a problem with a system that I dual booted from two HDDs. When I removed the second drive my computer wouldn't boot. Nothing I tried worked and that included using Macrium to create the boot partition. In the end I fixed the problem by doing steps 1 - 4 of what you posted.
Yes, I had to learn by trial and error.
I thought I was clever, so I used Minitool to copy the 100 MB partition.
and it worked, but the PC continued assigning drive letters left and right.

Finally, I did the one thing I should have done two days ago: I removed one of the hard drives and installed Windows.
 

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If I had enough time on my hands to be able to risk making mistakes then rectifying them, I would use this guidance to create a new EFI System partition on the correct disk:-
manually setting up a new drive and its partitions [NavyLCDR #3] - TenForums
I'd make my system image beforehand as normal.
I'd use this guidance just as if the OS was Windows 10 because I am ignorant of any differences.
NavyLCDR said:
The method I like to use is to set the new drive up manually. Assuming UEFI booting: use diskpart to create a 100 mb EFI system partition followed by Microsoft's recommended 16 MB MSR partition. Then use a program such as Macrium Reflect or MiniTool Partition Wizard to clone or copy the existing C: drive partition to the new drive. Then use the bcdboot command to populate the EFI system partition on the new drive with boot files from the newly copied OS partition.

The command sequence looks like this:

Code:
diskpart
list disk
select disk # <-replace # with the actual number for the new drive
clean
convert gpt
select part 1
delete part override
create part EFI size=100
format fs=fat32 quick
assign letter=a
create part MSR size=16
exit
exit

Now copy your existing C: drive OS partition to the new drive. Resize it during the copy if you want to fill the whole drive. Once the partition is copied, make sure to give it a drive letter using whatever software you use for the copying. Let's say you gave it drive letter E:. The last commands would be:

Code:
bcdboot E:\Windows /s A: /f UEFI
mountvol A: /D
exit

Restart your computer, but make sure to go into BIOS settings and set the new HDD as the first boot drive.


All the best,
Denis
 

My Computer My Computer

At a glance

Windows 11 Home x64 Version 25H2 Build 26200....
OS
Windows 11 Home x64 Version 25H2 Build 26200.8037
I once had a problem with a system that I dual booted from two HDDs. When I removed the second drive my computer wouldn't boot. Nothing I tried worked and that included using Macrium to create the boot partition. In the end I fixed the problem by doing steps 1 - 4 of what you posted.
I had that problem once and found the BIOS by default was set for AHCI/RAID and I had 2 drives installed. Ended up removing one drive and reinstalling Win10 then after all was working connected the second drive. RAID 1 is a mirror [copy] of one drive to the second. RAID 0 is striping [data spread across both drives for more storage], remove one drive and everything can be lost. I use RAID 1 with my 2TB NAS [2 x 2TB drives].
 

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    Win11 Pro RTM Version 24H2 Build 26100.4202Intel Core i5 11th Gen. 2.40GHz12GB
    OS
    Win11 Pro RTM Version 24H2 Build 26100.4202
    Computer type
    Laptop
    Manufacturer/Model
    Dell Vostro 3400
    CPU
    Intel Core i5 11th Gen. 2.40GHz
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    12GB
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    256GB SSD NVMe M.2
  • At a glance

    Win11 Pro RTM Version 24H2 Build 26100.4202Intel Core i5 10th Gen. 2.90GHz16GBOnboard, no VGA, using a DisplayPort-to-VGA a...
    Operating System
    Win11 Pro RTM Version 24H2 Build 26100.4202
    Computer type
    PC/Desktop
    Manufacturer/Model
    Dell Vostro 5890
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    Intel Core i5 10th Gen. 2.90GHz
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    16GB
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    Onboard, no VGA, using a DisplayPort-to-VGA adapter
    Monitor(s) Displays
    24" Dell
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    512GB SSD NVMe, 4TB Seagate HDD
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