Install different operating systems on separate SSDs

Welcome to the Dell Community @valv384 

When you installed Linux, did you change any BIOS settings???

Did you then install W10/11 using the same BIOS settings???

Best regards,

U2

I've installed both Windows and Linux (usually Fedora or Ubuntu) on my Dell laptops for some time. I've never considered switching the boot OS by changing BIOS settings.

To dedicate a drive to each OS I suggest the following.

• Install Windows on one of the drives.
• In the BIOS change the boot sequence so that the future Linux drive is first and the Windows drive second.
• Install Linux.
• During the install allow GRUB to see the Windows drive and include Windows as a boot option.
• In the BIOS leave both drives enabled and the Linux drive first in BIOS boot sequence.
• Choose which OS to boot from the GRUB menu.

You end up with a drive that is 100% Windows and a boot drive that is 100% Linux except that GRUB knows about and can start the Windows bootloader. Windows cannot access the native Linux file systems, and by default the Linux OS cannot access the Windows file systems. Linux will have access to the Windows data only if the NTFS drivers (ntfs-3g) are installed and someone mounts the Windows file systems.

The only risk remaining in this setup that's eliminated by disabling the other drive in the BIOS is accessing the partition tables using Windows Disk Manager or, in Linux, an app such as parted or GParted.

-Bob

Welcome to the Dell Community @rwzeitgeist 

If the Hard Drive mode is set to RAID or UEFI in the BIOS, will you be able to install Linux???

Best regards,

U2

You meant RAID or AHCI. Those are two different mass storage interfaces. Linux wants to use AHCI while Windows will use either one.

UEFI (Unified Extensible Firmware Interface) is the firmware interface specification that, among other things, enables verification of the cryptographic signatures of the critical components that run during the boot sequence. You want to leave UEFI turned on in the BIOS. You need to install a Linux that works in a UEFI environment. Ubuntu, Fedora, openSUSE, Red Hat Enterprise Linux, and probably some others include the necessary support.

I switched to AHCI mode and verified that Windows booted correctly before installing Linux. Running in AHCI mode is the Linux default unless you locate and install an appropriate RAID driver during installation. IMNHO the hassle isn't worth it unless you really intend to set up a RAID array. Here's a discussion of how to switch from RAID to AHCI without reinstalling Windows: How to Switch from IDE to AHCI on SSD Without Reinstall.

My Precision 7560 dual boots Windows 10 and Ubuntu 20.04 LTS with the BIOS set to AHCI and secure boot turned on.

-Bob

@valv384 

So all you needed to do was to go into the BIOS and set "Boot Mode" to AHCI.

Install Linux on one drive and then load Windows on the other drive.

At power-on press "F12" to boot to either OS.

"GRUB"???

Best regards,

U2

---

@U2CAMEB4ME wrote:

"GRUB"???

GRUB = "GRand Unified Bootloader"

During system startup the system ROM code loads the first bit of GRUB from the first sector of the drive, then that code loads the rest of GRUB. GRUB then presents the user with a menu of options, including the operating systems GRUB has been configured to boot. The user selects an option and GRUB then starts the appropriate system-specific boot loader.

On a Windows-only system the code on the drive's first sector loads the Windows bootloader.

Most Unix distributions include GRUB. During GRUB installation when the installer finds a bootable drive, the installer will set up GRUB to load that drive's boot code. GRUB on my 7560 offers to boot into the BIOS, Ubuntu, or Windows.

-Bob

I had my Precision 7750 working with Windows on one SSD and Ubuntu 21.10 on the other. For a while, I could choose between the two in the Grub menu with no problem. But now Windows won't start and all I get is an error when i try to start Windows. Any idea why this can happen??

Welcome to the Dell Community @rwzeitgeist 

Sorry but the question was not what "GRUB" was, but the unnecessary need to use it.

Best regards,

U2

Actually I didn't need to change the boot mode to AHCI/NVMe like I thought. I left it on Raid. I then disabled one drive and then installed Windows. I then disabled the windows drive and installed linux on the other drive. So both drives don't know about the OS on the other. (This is important because linux will not let you set up full disk encryption if it detects another OS on the computer).

I forgot to mention I then had to fix the boot configuration in the bios. The UEFI bios has its own loader to determine what OS to boot. It saves a link to the loader for each OS on the firmware. (These links are what you see when you press F12 on boot to choose what you boot from). When I installed linux it removed the option to boot from windows from the bios. I ran windows repair from a USB drive which added it again.

So basically installing ubuntu deleted the option to boot from windows from the bios. It didn't touch any data on the windows SSD. After I fixed the bios I could boot into both windows and linux by pressing F12 during boot.

Regarding GRUB, it is part of linux which makes it easy to be able to dual boot operating systems. Its gets installed automatically when you install linux and lets you switch between windows and linux. It makes everything much simpler as you don't need to configure anything but you cannot use full disk encryption on both windows and linux like I wanted to do.