Windows 11 install next to Windows 10 on a different SSD

iammike · 1 Week Ago

Hi Guys,

I want to install Windows 11 on another SSD to Dual Boot between 11 and 10.

My current windows (10) is installed on Drive1\Partition3 (C:\)

The problem I think lays in the fact that the EFI directory is located on Drive0\Partition2 which is the SSD where I want install Win 11.

So when the install of Windows 11 starts will it format that EFI part or not?

The SSD where I want to install Windows 11 on is now in use to store Data, but can be formatted

Thanks for any tips you can give me.

Ps: I would like to install Windows 11 via WinNTSetup 5.3.4.

TiA

Edit:
1- Image of my Windows install already done.
2- I made a backup of the BCD with Bcedit /export

Edit 2:

I just noticed something. The Recovery partition on Drive0 is on the beginning of the Drive and only 499 MB, the EFI (Fat32 part) is the 2nd one, this will cause future problems with another Recovery Partion update

Pentagon · 1 Week Ago

OK Rightclick on Start

and select "Diskmanagement"
Make sure that te colums 1 + 5 of the upper part are readable.

And, of course I forgot to mention: Post a screenshot of the Diskmanagement

iammike · 1 Week Ago

Windows 11 install next to Windows 10 on a different SSD-dmg.jpg

Windows11Pro is the drive where I want to install Windows 11 (that drive is currently empty) (so it's just a label)

Pentagon · 1 Week Ago

It's easy. How big do you want your future WIN11 C-Partition?
I believe that 150 GB for a C-Partition is big enough.

- - - Updated - - -

Copy the attached file to your D-Drive and run the command
cmd
C:\Windows\System32>

DiskPart /s D:\disk0.txt

and check Diskmanagement. It can be changed any time.

The EFI-Conversion on Disk 0 will be done later!

iammike · 1 Week Ago

Re: Disk Size, whole of the 500 GiB (minus the size of the recovery part (2GiB?) is good for me, even the Disk for Windows 10 is as you can see is 230 GiB with 1 GiB for the Recovery Drive.

I will wait and come back to you soon (I think tmrw) as I will be away from the PC. So will also then start installing Windows 11.

Thx appreciated

Pentagon · 1 Week Ago

I have a 2 GB Recovery as well, because my Macrium Emergency is there also.

Windows 11 install next to Windows 10 on a different SSD-screenshot-2024-04-20-133300.png

In your case you just have to transfer the EFI from Disk 1 to the prepared partition 1 on disk 0 and you are ready.

If you want, you just have to change the size in the script to 2048
rem === 4. Recovery partition ======================
create partition primary size=1024

nothing else

The attached script creates the same layout as above with only (1) bigger data partition.
Play with the sizes in the script. As long as you don't install your OS, it's safe.

NavyLCDR · 1 Week Ago

This is what I would do.
1. On the running Windows 10 system, run "reagentc /disable". This will move the recovery environment files to their storage location under C:\Windows\System32\Recovery.
2. Delete the recovery partitions on both disk 0 and disk 1.
3. Expand the C: and E: partitions to fill the rest of the disk.
4. Do a standard Windows 11 clean install to the partition currently containing E: . This will automatically set up dual booting.
5. You can decide if you want to populate the EFI partition on the opposite SSD using the BCDBOOT command if you want both SSDs to be bootable.
6. On the old Windows 10, run "reagentc /enable" which will enable the Windows 10 recovery environment but it will not be in a seperate partition, it will be under C:\Recovery.

iammike · 1 Week Ago

Thx Guys, really appreciated.

NavyLCDR said:

This is what I would do.
6. On the old Windows 10, run "reagentc /enable" which will enable the Windows 10 recovery environment but it will not be in a seperate partition, it will be under C:\Recovery.

That is a great idea, so I can also back this up to my NAS.
Would you need to do this for BOTH OSs (so Win10 and Win11)? I guess so.

NavyLCDR said:

This is what I would do.
5. You can decide if you want to populate the EFI partition on the opposite SSD using the BCDBOOT command if you want both SSDs to be bootable..

What is the disadvantage of having either of the SSDs non bootable? I think if I dislike Win 11 and decide to format (the current) E:\ and that is the only bootable one then the current C:\ (Win10) won't boot? Correct?

Thx again, appreciated

Edit: Would need the BCDBOOT cmdline parameters please

Pentagon · 1 Week Ago

@iammike

Great ideas when you ignore the unallocated space of 500 MB?
Great idea when you get a new Recovery Partition whenever you run an inplacement?

When you have a certain knowhow level you can play with configs, if not follow the Microsoft Guideline!

Megahertz · 1 Week Ago

If drive 0 has no data, do a win 11 clean install, deleting all partitions on the drive and then proceed.
You must detach (power or SATA cable) drive 1 (win 10) or you will end with Win 11 on drive 0 and the boot manager (on EFI partition) on drive 1.

- Boot from Win 10 and on a CMD window as administrator type:
reagentc / disable

-Shutdown and detach (power or SATA cable) drive 1 (win 10)

Windows can be installed in two ways: Legacy-MBR or UEFI-GPT
To install as Legacy-MBR you must boot the installation drive as Legacy
To install as UEFI-GPT you must boot the installation drive as UEFI.

As you have a UEFI BIOS, you should install as UEFI-GPT
Detach any other drives (SATA or Power cable) from the MB.

During POST, press F8(?) to launch the boot menu. You will see two options for the USB drive. USB UEFI (Name) and USB (Name). Select USB UEFI (Name) to install as UEFI-GPT.
Don't enable updates or connect to the internet during installation.
Go to install and delete ALL partitions on the main drive till you have one and only one unallocated space and then proceed.
If you want to use a local account What is "oobe\bypassnro" | Windows 11 Forum
After Win 11 installation, shutdown and attach drive 1 (the power or SATA cable).
Boot from Win 11 and post a Disk manager image.
Next step is to verify if Win 10 can boot. If the boot manager was on drive 0 you need to create a boot manager on Win 10 EFI partition (easy task).

Doing this way win 10 and win 11 will be completely independent, each one with its own boot manager and recovery environment.
And win 11 will have all the partitions and on the right order.