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May 20, 2023
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fter having a crash of my old pc because of too many operating systems on one HDD (- and one overwrote systemfiles of the others), I wanted to try a different way. In this way, I want to use my main operating system on the internal storage. The 2 and 3 operating system should run on an external SSD. But it has to be that way, that this external system does not have any access to my internal HDD. Additional to this the external system should work like a common one, so that I can install additional software or update the system itself. In other words: If I run the linux from the external media, it shall use the everything from my pc (without the internal hard disk). For the external system I would like to use ubuntu. However another system would be possible too.

Do you know a way to get it done with ubuntu?
Is there allready existing an operating system for get run on usb stick, that does not touch internal media (where I can install software)?

kind regards

I have several hard-drives that I can connect using SATA/USB cable for distro testing, all I do is install a new distro to the USB external drive,
Welcome to the forums.
It's possible what you're looking for, but you have to follow accurate instructions.

Ubuntu's installer, Ubiquity is a bit difficult to deal with. Before it shows any partitions it has to scan any internal HDD or SSD and it takes a long time before deciding to pick the largest one and offer to use half of it for the Linux OS. It's frustrating. Beyond that, it's possible to install the OS to an external disk to boot from but again saying, you have to pay close attention to what is done.

On the external disk to install you will need at least three partitions. At first you have to create a 2MB space at the very beginning, before creating a 512MB EFI System Partition (ESP). Some OS's settle for 300MB size but larger doesn't hurt if the extra space could be spared. Then a "swap" partition of 2GB, or at least the size of your RAM if you expect to hibernate the system. In between the "root" partition to format as "ext4" or "btrfs" or another.

In Ubiquity these have to be chosen exclusively. Which means you have to set "do not use this partition" for the ESP of your internal disk, and "use this partition" for the ESP of the external disk. Also make sure the "root" partition of the internal disk is not being used, nor the "swap". They must be set for the external disk. The mount point for the root partition is "/" (only forward slash). The mount point for ESP is "/boot/efi".

These tips should work also with the Debian Installer.

I almost forgot to mention that installing the bootloader could be the major problem. Many installers expect without compromise to put it into an internal HDD/SSD because "duh the user will want to be able to boot from it afterward". The Ubuntu installer insists on an ESP to work with but might not even use it, which is another frustration out of this program. The only way I have found out of it is to install another Linux OS (keep reading below) and to use the GRUB menu it generates to go into Ubuntu. But that is more hassle and technical explanation than you could probably handle right now LOL.

Other Linux OS support external installation if they carry Calamares installer. It's better to accept the "default" option for using the entire disk (the one to install to). It's because I have pre-arranged the partitions before running the installer, but then the thing refuses to boot giving me an useless error.

I would have recommended Spiral Linux over Ubuntu, however the ISO is almost a year old and might not be converted to the soon-to-become-stable Debian "Bookworm". You could also try an Arch Linux-based thing like EndeavourOS or Manjaro but that is really cutting the skin there.

If you have another concern you could always come back here and talk about it. Good luck.
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Sounds to me like you may have had 'auto' mounting on your distros - turn it off - use external disks, then you should only see the disk that the present O/S is installed on - of course, other disks will still be available using 'mount' if you need them.

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