Installation of Ubuntu on a Windows desktop

[alan44zz]

Hello,
Sorry to post such probably stupid questions but...

I have a desktop running under Win10 and want to install Ubuntu24 on it, on a dedicated HD.
In the computer U have 6 hard disks, all used by the Windows system, MBR partition style and NTFS formatted.

I made a bootable USB disk with Ubuntu, and have 3 questions:

1- About dual boot. As I understood, GRUB will manage the boot. Will it work correctly with the MBR partition style for all disks ?

2- Will the other disks be concerned by the Ubuntu installation ? I remember that, maybe 15 years ago, I tried to install a Linux OS in a Windows desktop and it "initialized" ALL disks inside. Data was lost... I can of course physically unplug the disks, but...

3- Will I be able to use the other disks in the computer, currently used by Windows, with Ubuntu ? Data only, not software of course.
I read online that is it possible but the exact question is to know if, after using them with Ubuntu (for example writing some data), can I use them again with windows, with all "new" data written by Ubuntu, usable ?

Thank you!

[ajgreeny]

As your Windows 10 is unusually installed in MBR/UEFI mode you will have to ensure that you boot the USB install drive in the same MBR mode which will then install Ubuntu in that mode.

Both OSs must be the same mode for grub to work and offer both at boot.

[grahammechanical]

I suggest that for safety's sake. Disconnect those hard drives that you use for Windows. Have just the har drive that you want to put Ubuntu on. After installation of Ubuntu replace those Windows drives. Then load into Ubuntu and open a terminal and run this command:

sudo update-grub

Watch the printout. Grub should identify the Windows operating system and when to bot you should get a Grub menu with options to load either Ubuntu or Windows.

This forum thread provides useful information

https://ubuntuforums.org/showthread.php?t=2491292

You may also need to install a special driver to read/write to NTFS drives.

This might be too much information. At least it shows the package you need is ntfs-3g

https://manpages.ubuntu.com/manpages...ntfs-3g.8.html

sudo apt install ntfs-3g

Regards

[yancek]

About dual boot. As I understood, GRUB will manage the boot. Will it work correctly with the MBR partition style for all disks ?

It can if you boot and install correctly. If you are very inexperienced it would probably be best to disconnect your windows drives. If you boot the Ubuntu install USB and from a terminal run the command below, it will tell you if you have a gpt Partition table or dos. I expect it will be a dos drive if windows is an MBR install which as pointed out above, is pretty unusual for the windows you are using. Must have pretty old hardware. If it is dos, then boot and install with your BIOS set to Legacy/CSM for the sake of simplicity. If you do an EFI install of Ubuntu on one physical drive and have a Legacy install of windows on a separate physical drive, the Ubuntu Grub should still boot windows. This works for me but for the sake of simplicity, I would install/boot all in the same mode. You need to know which drive you are installing to and know Linux drive/partition naming conventions.

sudo parted -l

As far as accessing and overwriting other disks, if you know the drive on which you wish to install Ubuntu and are familiar with Linux drive/partition naming conventions it should not be a problem. Installing Ubuntu properly to a specifically selected drive will not affect other drives. Maybe you did an LVM install without knowing what it did in your previous attempt.

You should be able to write data to windows partitions with a windows filesystems but you are not going to get a guarantee from anyone.

[alan44zz]

Hello!

Well, I installed Ubuntu, ont its dedicated HD, no problem. Just the dual boot doesn't work.

In the (legacy) BIOS I put first ubuntu disk, it boots directyly into Ubuntu. No Grub menu.

In the (legacy) BIOS I put first windows disk, it boots directyly into Win 10.
I then here tried to add a boot entry with EasyBCD : Grub2, it detected the Ubuntu path (attached picture)
When I reboot, I get the "windows choice" between Win10 and Ubuntu.
If I choose Ubuntu, it stops at the screen shown in the second attached file.
What must I do if I want this first option ?


In fact as my goal is to get rid of Windows, I think I should put the Ubuntu disk at first in the BIOS boot section, and try to get Grub offer the option to boot in Windows too. So later if I remove the WIndows disk, all will work smoothly.
In this option as told above, the box boots directly into Ubuntu, no Grub menu.
What must I do if I want this second option ?

Thank you

[alan44zz]

According to the current situation, seems there's something wrong

[ajgreeny]

See Boot-Repair in my signature below and follow the instructions there to run the Boot-Info-Script.

Do not run the default repair just yet but simply copy back here the pastebin link you get which will show us a lot more about your system.

[yancek]

So you have verified that windows is installed in Legacy mode and Ubuntu is also installed in Legacy mode on a different physical drive, correct? What you describe is expected behavior as Grub in Ubuntu no longer probes for other operating systems by default. Boot into Ubuntu and using a text editor and sudo, edit the file /etc/default/grub to add the line below:

GRUB_DISABLE_OS_PROBER=false

If that line exists in the file make sure you do not have # at the beginning of the line and if you do, delete the # character. Save the change and run sudo update-grub and you should see output for other operating systems detected if any are found on the connected drives. Watch for a windows entry and if you see one, set the Ubuntu hard drive to first boot priority in the BIOS.

Verify that Ubuntu is not UEFI. Is Ubuntu on a GPT disk? You can get this information with the simple command below which will List the partition info:

 sudo parted -l

If both systems are Legacy, I would expect EasyBCD to work but it won't work if Ubuntu is UEFI and I don't know how or if it will work on a GPT disk so doing this check should help. If you want to use windows software like EasyBCD, post your question on a windows forum. I used it in the past and it seemed to work but it's been years.

[alan44zz]

https://paste.ubuntu.com/p/K28XWgH7zj/

[oldfred]

You show mostly BIOS/MBR, but do have sda as gpt partitioned.
Not sure how you have Windows in old BIOS/MBR mode.
Microsoft has required vendors to install Windows in UEFI boot mode from gpt partitioned drives since 2012.
The old BIOS/MBR mode only was kept so old hardware could get an install of Windows 8.
New systems starting in aboutn 2020 are UEFI only.

Do not get rid of Windows until you have converted all NTFS partitions to a Linux format. Windows will need chkdsk or defrag and that can only be done from Windows.

Looks like you are tying to dual boot from Windows, you need to dual boot from grub.
But grub only boots working Windows. That means no chkdsk required and fast startup must be off. Windows updates may turn fast startup back on. Fast startup sets hibernation flag and prevents the Linux NTFS driver from fully accessing the NTFS partitions to prevent loss of data when hiberfile restored when booting Windows.

But long term you need to consider converting drives to gpt. Conversion from MBR to gpt will totally erase entire drive, so good backups required.
Ubuntu will boot in BIOS mode from gpt partitioned drives if you add a bios_grub partition. I booted Ubuntu from gpt with BIOS starting in 2010, so I know it works. With first UEFI system I used gpt with both bios_grub and ESP - efi system partition which is required for UEFI boot. But with bios_grub partition I could easily reinstall grub for BIOS boot.