First, let’s clarify the title. Separate Disk means that we will install Debian on its own disk. So get your disk ready and ensure you don’t need anything on that disk because it will be formatted. Standalone means there will be no other operating system connected to the PC during the Debian installation process.
So if you want to install Debian this way and you have a Windows installation on the PC already, disconnect the Windows disk. After you finish the Debian installation, reconnect the Windows disk, and you will be able to switch between the systems - Windows and Debian - from the boot menu, or from the BIOS or UEFI or other ways. This way, we ensure that the GRUB boot loader will be installed on the Debian disk and not on the Windows disk.
Second, you will need a Debian 12 Installation Media, such as a Debian 12 Bootable USB Drive. Our article on how to create a Debian 12 Bootable USB Drive with Rufus might help you.
Third, you will need to insert the USB Drive into the computer, then restart the PC and access the BIOS or UEFI. Adjust the boot priority to boot from the USB Drive, or you can enter the boot menu and boot from the USB Drive directly. Our article on how to boot from a USB Drive might help you.
Now, from the Debian installer menu, you can see if you are booted with UEFI or BIOS mode. then Choose Advanced Options, then Graphical Expert Install.
Next, follow the steps in the install process one-by-one. Select each step and click on Continue to set it up. This includes choosing the language, location, locale, and configuring the keyboard.
While detect and mount installation media is selected, click on Continue. Keep the default option checked and click on Continue.
While load installer components is selected, click on Continue. You can select any components from the list if needed.
While detect network hardware is selected, click on continue. Then, configure the network by clicking on Continue until you reach the hostname screen.
Type a hostname for the system or leave it Debian as default and click on Continue. Leave the domain name blank as most people won’t need it and click on Continue.
Now, set up users and passwords. Choose whether to allow login as root. If yes, type a root password twice.
Next, create a normal account. Type a name for the user account. This will be the username. You can change it if you want. Then, type a password for the normal user account twice.
Configure the clock, click on Continue. Select yes or no based on your preference. Select your time zone based on the location you chose.
Detect disk, click on Continue, partition disks, click on Continue.
Now, let’s partition the disk. As we said, we will be installing Debian on its own disk. Just know disks in Linux will show as sda, sdb, etc., or nvme0n1, nvme1n1 etc., and partitions will show as sda1, sda2 etc., or nvme0n1p1, nvme0n1p2.
Choose the partitioning method, Guided - use entire disk, then click on Continue and choose the disk then click on Continue, then keep the default option All files in one partition then click on Continue, then Debian will partition the disk automatically.
Or choose the partitioning method, Manual, and if you have a brand new drive, the drive will show without partition table or free space. Just double click on the disk and select Yes to create an empty partition table or free space then click on Continue, and if you partition table type screen choose GPT or MBR / MSDOS, GPT for UEFI, mbr/msdos for BIOS.
If you have a used disk, you might see a few partitions already exist. Just double click on the partitions one-by-one and select Delete this partition then click on Continue.
The partitions for UEFI boot, are as follows in order: an EFI System Partition: 500 MB in Size or More, a System Partition: Max Size Minus Swap Size, a Swap Partition: Same Size Of Your RAM or Double it if you have low memory RAM.
(Swap partition is not required but recommended, instead of it you can set up a swap file later).
Now, double click on the free space to create the first partition which will be the EFI System Partition also known as ESP, keep the default option Create a new partition selected and click on Continue, now give the partition a size, for the ESP is recommended to be 500 MB at least and click on Continue, keep the default option Beginning selected and click on Continue, at the partition settings screen double click on Use as option and select EFI System Partition and click on Continue, then select Done setting up this partition and click on Continue.
Now, double click on the rest of the free space again to create the second partition which will be the System partition, keep the default option Create a new partition selected and click on Continue, now give the partition a size, for the system partition give it max size minus the size of the swap partition we will create later if you plan on creating one and click on Continue, keep the default option Beginning selected and click on Continue, at the partition settings screen double click on Use as option and select Ext4 journaling file system and click on Continue, then double click on Mount point option and select / or the root file system and click on Continue then select Done setting up this partition and click on Continue.
Now, double click on the rest of the free space again to create the third partition which will be the Swap partition, keep the default option Create a new partition selected and click on Continue, now give the partition a size, which should be the rest of the free space after doing some math to create the second partition and click on Continue. A Swap Partition can be the same size of your RAM or double it if you have low memory RAM (Swap partition is not required but recommended, instead of it you can set up a swap file later). At the partition settings screen double click on Use as option and select Swap area and click on Continue, then select Done setting up this partition and click on Continue.
The partitions for BIOS boot, are as follows in order: a System Partition: Primary, Max Size minus Swap Size, a Swap Partition: Logical, same size of your RAM or double it if you have low memory RAM (Swap partition is not required but recommended, instead of it you can set up a swap file later).
Now, select Finish partitioning and write changes to disk and click on Continue, then select Yes to write the changes to disk and click on Continue.
Install the base system, click on Continue. At kernel to install screen, keep the default option selected. At drivers to include in the initrd, select generic if planning to use the system on other Computers, or targeted if you will use the system only on this PC.
Then, at Configure the package manager which is called ‘apt’ in Debian and Debian-based Linux distributions, select No for Scan extra installation media and click on Continue. Select Yes for Use a network mirror and click on Continue. choose a mirror country. I will go with the United States and click on Continue, then choose a mirror archive. I will go with deb.debian.org and click on Continue.
For Participate in the package usage survey select No and click on Continue.
For the use non-free firmware and use non-free software screens, select Yes. For enable source repositories in apt, select No. Keep the default options selected for the services to use screen, and click on Continue.
Select and install software, click on Continue. Choose your preference for updates management and select No for Participate in the package usage survey.
For Software selection select the desktop environment, DE for short, you want to use, popular options can be GNOME, KDE Plasma, Cinnamon, lightweight options can be XFCE, LXQT, and others, you can also select multiple desktop environments and switch between them at the login screen. I will go with GNOME desktop environment. If you need an SSH server or web server you can select these options, and keep Standard system utilities selected, and click on Continue. Just know that you can install any of the desktop environments later by typing tasksel in the terminal.
For install the grub boot loader, click on Continue. Select No for force grub installation to the efi removable media path, and Yes for update NVRAM variables if you prefer to boot into debian automatically. Choose Yes or No for run os-prober automatically to detect other operating systems based on your preference.
Os-prober is used during installation to create a GRUB boot menu that shows all discovered operating systems on the system. It can also be reconfigured after the debian installation.
To finish the installation, click on Continue. Answer Yes or No to the question is the system clock set to UTC, then click on Continue. Finally, click on Continue to reboot.
Now, at the login screen if you installed multiple desktop environments you can switch between them by clicking on the gear icon in this case, and choose the DE you want then enter the password for the user account you created, then hit enter, and you will be at the desktop.