Help installing dual boot on separate drives

[u/Jack_4316]

I have two NVME drives, one with Windows (UEFI) and one which is completely empty.
I want to use the empty drive for EOS, and I'll need to switch between to the systems pretty often (basically daily).

From searching online, I get that I should use GRUB, and from my understanding the steps I should take are:

• Install the second NVME
• Disable Secure Boot
• Boot from the USB with EOS
• Start the installer and pick GRUB

Afaiu, I shouldn't do anything with the empty drive from Windows, as the EOS installer will deal with it. (So no partitioning or shrinking).

What I'm confused about is what I should do in the drive section, as "Erase Disk" seems to be the most logical option when using a completely different and unused drive, but I see many talking about manually creating an EFI partition or picking "Install alongside", while others just say to pick the right drive and select "Erase Disk" (Focusing on the 2 disk setups).

I can't unplug the Windows drive so I just want to make sure I have everything clear and prepared.

Will I need to also select the drive with Linux as the main boot device once this is done? So that I can always pick between the two OSs, as from what I get, GRUB would be on the second drive only.

Yes this is all very newbie but I like having things clear, have patience ;-;
A step-by-step guide would be useful

Thanks in advance to anyone reading ^^

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[u/moopet]

You don't need to use grub if you don't want to. I have a similar setup on one PC where I installed systemd-boot, making an EFI partition (yes you can have as many as you like) on the empty drive and pointing the system bios at that drive. That means that if I want to, I can remove the linux drive completely and it'll go back to being a Windows machine kind of by magic, and also that Windows won't break the boot loader during an update (which is kind of Windows "thing").

That said, your bullet list seems fine. Make sure that when you erase the disk you're definitely 100% sure you pick the new drive and not the old one!

Whether you'll need to pick the other drive in the bios depends where your efi partition is. I'd say follow the defaults in the installer, and if it doesn't work straight away, pick the other drive and see if it boots then. It'll be one or the other, and it won't damage your PC to try to boot of the wrong one.

[u/Jack_4316 → u/moopet]

Thanks for the response!
Do I need to create the EFI partition from Windows before installing EOS or is it something I can do from the EOS installer?

[u/Paxtian → u/Jack_4316]

The EOS installer (Calamares) will take care of this for you. It should automatically be that the EFI is the default that you BIOS chooses to boot from (so, it'll pick Grub or whatever boot loader you go with), but if not, you might need to configure your BIOS to choose that instead of Windows by default during boot. For me, it's been automatic across several machines.

And yeah, choose "erase disk" during installation, and be sure to select the empty drive rather than the one with Windows on it.

You may want to go with BTRFS and install Timeshift to have backups in case something goes wrong in the future. It's easy enough to do and the peace of mind is worth it.

[u/Jack_4316 → u/Paxtian]

I will then, thanks! Would disabling the Windows drive work the same? To avoid any potential issue

[u/Paxtian → u/Jack_4316]

I'm not sure what you'd do to "disable" the drive. Through BIOS? Short of physically removing it I'm not sure how it would be completely disabled. But in the live environment, you can see in the file system what that drive is called (/dev/nvme...). And when you're installing, you'll be asked which drive to install to, so just pick the other one, not the one with Windows on it.

[u/Jack_4316 → u/Paxtian]

Yeah that's what I meant, it was just something I saw some people suggest on forums. I'll make sure to select the right drive