Can you install Debian on an external hard drive?
Short answer is «yes», it is possible. If the external hard drive is connected via USB, you can choose to have Debian installed on it without fear of damaging the data on your internal hard drive that boots your current operating system (typically Windows or macOS).
Can I install Ubuntu on an external USB hard drive?
To run Ubuntu, boot the computer with the USB plugged in. Set your bios order or otherwise move USB HD to the first boot position. The boot menu on the usb will show you both Ubuntu (on the external drive) and Windows (on the internal drive). Choose the one you want.
The Debian installer will check for all connected drives to your computer. If the external hard drive is connected via USB, you can choose to have Debian installed on it without fear of damaging the data on your internal hard drive that boots your current operating system (typically Windows or macOS).
Is it possible to mount a GPT disk?
You likely cannot mount this HDD because even though the kernel has detected it (in the dmesg output) the HDD hasn’t been partitioned or formatted with a filesystem so that it can be mounted. This will list all the GPT devices & partitions. You can create a partition using sfdisk as well.
Can you install Linux from an external HDD?
You can even install from a USB drive to an external HDD. It is possible that your BIOS (UEFI settings to be precise) has secure boot enabled and is missing an administrator password that won’t let you boot the installer from a USB (or other media) as a security policy.
Is there a problem mounting a DVD drive?
The problem occurred when the drive in question was connected via a USB SATA controller. In order to access the drive I unplugged the DVD drive from the motherboard onboard SATA controller (I have no spare sockets) and plugged the drive in (no reboot required – SATA is hot pluggable).