How to dual boot Windows 10 and Debian 9 | Tutorial

How to dual boot Windows 10 and Debian 9


In this post we will go through the process on how to dual boot Windows 10 and Debian 9. In this scenario, we have WIndows 10 installed on a single drive, created a separate partition for Debian installation on the same drive and during the setup process, configured the dual boot for both operating systems. It is advisable to backup your system first before making any new changes, since all this will be performed on a single HDD. Also, check you PC how it boots(UEFI or Legacy) and make sure both OS are installed in the same mode. Here you can find a tutorial on how to create a Debian bootable USB in Windows 10

Requirements for this process:

1. Debian bootable USB

2. Available free HDD space or a second HDD

Assuming you have Windows first installed, first step is to create a partition for the Debian system. For this you can use a disk management utility in Windows or a third party partition software. There a lot of them that are free and good.

Before you do anything, make sure to backup all the important data you have and do this process only if you have free space on you HDD or if you have a second HDD – that would be even better.

Bellow you will find a video tutorial as well.


Creating partition for Debian installation

For this tutorial, we will use disk management utility. Start the utility by clicking the right click on the start menu and select the disk management option. When the window gets opened, on the bottom you’ll see all your drives and partitions listed. Next step is to create a new partition that we will use for our Debian installation.

If you have more than one partition on your PC, choose the one which has more free space. In this case, we only have one partition and it’s a Windows partition. So, we will select our Windows partition, click right click on it and select the option Shrink Volume. Once more be sure to have free space on any of your drives.

After you click on the option Shrink volume, it will open you a new window. In this windows you will set up your new partition.

In the field – Enter the amount of space to shrink in MB – you will enter and allocate free space for your new partition. So, enter how much space you want for your new partition to have and click on shrink. Keep in mind again that you need to have enough free space on your drive.

Once that is done, on the bottom of the disk management window, a new partition you created will show up and it will have Unallocated label on it. Next step is to insert your bootable Debian USB on your PC, restart the PC and boot the Debian installation from the USB.

Debian installation

I recommend to choose the installation with the graphical interface.

Once you start the installation, first it will prompt you to choose the language, select your location and choose the keyboard layout.

After that, it will prompt you to enter the hostname for your PC. By default, this will be already filled but you can change it if you’re going to do networking afterwards.

Next it will ask you for the domain name. You can leave this empty if you plan to use Debian for personal and home use.

Root account setup

In the next screens, you need to set up your root account – Installation will ask first for the password then the next screen will ask you to enter the username for the root account. After that, it will ask you to set up your personal account and the process will be the same.

After the account creation, next step will be to choose your time zone.

Formatting Debian partitions

Now we need to partition our Debian installation. You’ll get this screen where it will prompt to choose how will you manage the partitions. Select Manual and click continue.

When you continue, you’ll get a windows that will have all your partitions listed. First we need to create a SWAP partition.

Select the partition that has a label – FREE SPACE and click continue.

The next screen will prompt you what to do with the new partition. You will select the option – Create a new partition and click Continue.

On the next screen, you need to enter the partition size in GB. For the SWAP partition it’s enough 1 GB, so just enter 1 GB and click Continue.

The next two screens will ask you what type of partition it will be and the position of the partition. In the first screen, select the LOGICAL partition and on the second screen, select the option AT THE BEGINNING.

Now you will get the edit the partition screen. In here we need to change the extension of our SWAP partition.

Double click on the selection – Use as, it will open a prompt with a list of partition extensions.

In the windows prompt, select the option – SWAP AREA and click continue.

Once you’ve finished, the installation will return to edit partition screen. On there, select the option – Done setting up the partition.

After that, you’ll be again at the first partition disk windows with the list of all partitions on your PC. You’ll see the new SWAP partition and underneath that, you’ll still have a partition with a label FREE SPACE. We’re going to again use that partition and format it. Now we’re going to create a regular partition for the system and personal data.

This time, the process will be much simpler than for the swap partition. Again double click on the partition with the label FREE SPACE to start formatting it. Now on the screen where it asks you to Create a new partition, instead of that option – we’re going to choose the option – Automatically partition the free space.

The installation will automatically format the partition as an EXT4 partition that will be used for the system installation. After it finishes, you’ll be again at the first partition screen. Select the option – Finish partitioning and write changes to the disk and click continue.

Package manager setup and GRUB installation(dual boot setup)

When you click continue, the installation will first prompt you are you sure to make the changes. Click YES and continue again. The installation will install the system and once that is finished, we will need to configure the package manager.

First, it will ask you do you want to use a network mirror – Click YES and continue.

Next step is to choose a Debian server. Installation will automatically choose a server but it’s recommended to choose a server from your country or the closest to your country.

Next to do is to select an archive mirror. Again, you can leave the selection by default but it’s recommended to choose one from your country or close to your country.

On the next screen, it will ask you to set up the HTTP proxy. It’s not mandatory, you can leave it empty. If you need to use a HTTP proxy for an internet connection then you enter the link of your HTTP proxy server.

Now here comes the last step and an important one. The dual boot set up. The installation will detect another operating system installed on the HDD and it will prompt you to install it’s own bootloader, which is the GRUB bootloader to maintain the OS booting. On the screen you need to select YES and continue.

On the next screen it will ask you on which HDD to install the bootloader. You need to select your main HDD where windows is installed.

Finishing up

And that is it. That was the entire set up, you installed Debian OS and also set up the dual boot with Windows. The installation will finish and reboot automatically. Once the PC boots again, you need to have this bootloader screen first where it prompts which OS to boot, Windows or Debian.

I hope you found the post useful and that the process was easy to follow. Thank you for your time.

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5 Responses

  1. Daniel says:

    Thank You very much for steps explanation, some 7 months ago I switched from Windows OS to Debian Linux-Cinnamon and I realy do not have idea why I didn’t do that before, anyway I still might need WindowsOS for some stuff and dedicated one free partition on SSD where Debian9 is installed with MBR Grub2 and what should be procedure shortly for installing Windows10 where in this case I have already installed Debian9 ?? Many thanx

    • MarkoNtech says:

      Hi there,
      Thank you very much for your feedback. If you decide to install Windows 10 where you already have Debian installed, what will happen is – Windows 10 installation will overwrite the GRUB bootloader – which of course will be inconvenient and the only way to fix that is to boot Live Debian again and from there re-install GRUB bootloader and to update it. Kind regards.

  2. CUNC says:

    Thanks, very useful post.

  3. Kevin says:

    Hey, windows 10 dont show up for me in bootloader, how can i fix that? I cant boot windows 10 so om stuck on debian now…

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