Move from single drive to multiple drive multiboot

[calaDan]

I currently have a working dual boot, Mac/Windows system on a single 500GB NVMe SSD. I have purchased an additional 1TB NVMe SDD.
I'm intending to rebuild the Windows install from scratch on the 1TB drive and then keep MacOS on the 500GB (expanding it to the full size of the drive).
What would be the process to achieve this without having to rebuild the mac installation?

 

[pastrychef]

I currently have a working dual boot, Mac/Windows system on a single 500GB NVMe SSD. I have purchased an additional 1TB NVMe SDD.
I'm intending to rebuild the Windows install from scratch on the 1TB drive and then keep MacOS on the 500GB (expanding it to the full size of the drive).
What would be the process to achieve this without having to rebuild the mac installation?

Just delete the Windows partition and expand the macOS partition. Disk Utility can do this.

 

[calaDan]

Thanks,
When I then install the new Windows build on the second drive how does that effect the EFI partition on the 500GB? Do I just format the 1TB drive as GPT and install as normal and let it have it's own EFI (100MB) for window - and would I then have to adjust the existing EFI on the Mac drive?

What I would like is to have the 1TB as the boot volume - containing the shared 200MB EFI partition and Windows.
MacOS on the second drive alone. Would that work?

 

[pastrychef]

Thanks,
When I then install the new Windows build on the second drive how does that effect the EFI partition on the 500GB? Do I just format the 1TB drive as GPT and install as normal and let it have it's own EFI (100MB) for window - and would I then have to adjust the existing EFI on the Mac drive?

What I would like is to have the 1TB as the boot volume - containing the shared 200MB EFI partition and Windows.
MacOS on the second drive alone. Would that work?

In my experience, the Windows 10 installer only messes with the EFI partition of the drive where Windows 10 is being installed. It should not mess with the macOS drive at all. When the installation is done, just go in to BIOS and set which drive you want to be first in the boot order.

Side note: When I've tried installing Linux on a system with macOS and/or Windows, it would try to install its bootloader (Grub) all over the place. So, if/when you ever want to install Linux, I suggest either (1) disconnecting your other system drives first or (2) make backups of the EFI partitions and restore them after the Linux installation.

 

[calaDan]

That is what I was hoping. Windows would be basically standalone. If I made it's drive the boot volume then it would go straight into windows - no sign of another bootloader. If I set the existing Mac drive as the boot volume then I would see Clover etc. I guess my only question there is if I can then boot to the new install of Windows on the other drive without altering the old shared EFI? I'm guessing it will just enumerate the available drives and boot to the OS on the volume I select?

 

[pastrychef]

That is what I was hoping. Windows would be basically standalone. If I made it's drive the boot volume then it would go straight into windows - no sign of another bootloader. If I set the existing Mac drive as the boot volume then I would see Clover etc. I guess my only question there is if I can then boot to the new install of Windows on the other drive without altering the old shared EFI? I'm guessing it will just enumerate the available drives and boot to the OS on the volume I select?

You don't have to make any changes to your existing EFI partition or to Clover.

You should be able to boot from either drive whether it be through BIOS or from the Clover boot menu.

 

[calaDan]

Thanks Mr Pastrychef!

So.. I'm thinking as a safe procedure I could..

1. Remove the existing 500GB drive (just to be extra careful)
2. Install the 1 TB Drive and Install Windows (via UEFI USB Install Media)
3. Reinstall the 500GB drive and set it as the first boot volume
4. Remove the old Windows partition and expand the MacOS partition via Disk Utility

Job done!

 

[pastrychef]

Thanks Mr Pastrychef!

So.. I'm thinking as a safe procedure I could..

1. Remove the existing 500GB drive (just to be extra careful)
2. Install the 1 TB Drive and Install Windows (via UEFI USB Install Media)
3. Reinstall the 500GB drive and set it as the first boot volume
4. Remove the old Windows partition and expand the MacOS partition via Disk Utility

Job done!

That should work fine. If you really want to be extra careful, you can make a full backup of your macOS before beginning all of this.