Flash Raspberry Pi OS

Download and flash Raspberry Pi OS onto the SSD.

Download Pi Imager

To flash the OS onto the portable SSD we will use a software utility called Raspberry Pi Imager. You can download it here.

Choose OS image

Now connect the portable SSD to your computer and launch the Pi Imager. First you have to select 3 options:

• Raspberry Pi Device: Choose Raspberry Pi 5 or Raspberry Pi 4 depending on the model you use.

• Operating System: Choose Raspberry Pi OS Lite (64-bit)

• Storage: Select your portable SSD

Raspberry Pi OS Lite does not include a GUI or extra utilities, allowing us to conserve system resources.

Apply custom settings

Click on Next. The imager will now show a popup to ask you if you want to apply customisation settings. Click on Edit Settings.

General Tab

• Set a hostname for the Pi on your local network

• Set a username and password (this will create a new user)

• Add your Wi-fi settings (that way the Pi will auto-connect at boot)

• Set locale settings by inputing your timezone and keyboard layout

Services Tab

In the previous tab, we ensured the creation of a new user and automatic Wi-Fi connection at boot. In this tab, we will set up an SSH service to enable direct login to the Pi after it boots.

We won't use password authentication. It's better practice and safer to use public-key authentication.

First we must generate a pair of keys for our user:

ssh-keygen -t ed25519 -C "[e-mail]"

Next we must copy the content of the public key (*.pub). Now in the Services tab of the Pi Imager:

• Click Enable SSH

• Choose Allow public-key authentication only

• Copy the content of the public key

Click Save, we are now done with the customizations.

Flash the OS

Back on the customisation popup, click Yes to apply the settings you just inputed. Click Yes again to flash the OS onto the SSD.

Once it's done, safely eject the SSD from your computer.

Make sure to safely backup your user credentials and your SSH private key.