Windows 10/11 on different drives - dual booting

Question

Hello, I plan to format my system and rebuild everything from scratch. I want to have dual boot, Windows 11 on one ssd, Windows 10 pro on another ssd. 1. Is it possible that each system has its own efi partition and still be able to dualboot? 2. Do I need to disconnect the other ssd in order for Windows to create it's own Efi? 3.Do I need another license for Windows 11 if the instalation is on the same machine registered to windows 10 pro?I got already the message for free upgrade, but I don't know if for 2 installations on same machine a single licence ( bios type one) will suffice.

Answer 1

If you have multiple SSDs in your system, you may want to disconnect or disable (in BIOS/UEFI settings) the drives that don't contain the OS you're currently installing. This helps avoid accidental data loss during installation.

1. Install Windows 10:
   • Insert the Windows 10 installation USB drive and boot from it.
     • During the installation process, select the appropriate partition for Windows 10 but do not format the EFI partition. Let Windows 10 create its system partitions, including its own EFI partition, alongside the existing one.
       • Complete the Windows 10 installation.
2. Install Windows 11:
   • Insert the Windows 11 installation USB drive and boot from it.
     • During the installation process, select the appropriate partition for Windows 11 but do not format the EFI partition. Allow Windows 11 to create its system partitions, including its own EFI partition, alongside the existing ones.
       • Complete the Windows 11 installation.
3. After both Windows 10 and Windows 11 are installed, you need to configure the boot manager. This can be done using the bcdedit command within Windows 11.

a. Press Win + X and select "Windows Terminal (Admin)" or "Command Prompt (Admin)."

b. Use the following commands to add a boot entry for Windows 10:

bcdedit /create /d "Windows 10" /application osloader

Set the device and path for the Windows 10 EFI partition:

bcdedit /set {GUID} device partition=C:

bcdedit /set {GUID} path \Windows\system32\winload.efi

Replace {GUID} with the actual GUID you obtained in step b.

d. Add an entry to the boot menu:

bcdedit /displayorder {GUID} /addlast

Reboot