Ubuntu – USB persistence not working

I think the best solution is to get a really fast USB 3 pendrive. Often the flash memory hardware is limiting the speed, so you should search for a pendrive with documented high performance on both reading and writing. See the following link and links from it,

Installation/FromUSBStick - Notes about speed | Ubuntu Community Help Wiki

I use Sandisk Extreme pendrives for this purpose, and I make persistent live systems in them with mkusb. Please search for current information via the internet in order to find alternative pendrives and methods.

You should also avoid installing too many program packages into the persistent live system. And you must not upgrade the whole system. This will make the system slow, and it might even make the system fail, because it will be choked with too much reading from the 'casper-rw' partition or file.

Persistent live Ubuntu

• I tested, and yes, you can remove the original ubuntu user after creating a custom user ID with a good password and admin (sudo) permissions.

  sudo add-apt-repository universe
  sudo apt update
  sudo apt install gnome-system-tools
  

  and you get a convenient tool to create a custom user,

  users-admin
  

  Remember the admin (sudo) permissions!

• It is a good idea to set the permissions of your subdirectories (in your home directory) to only allow your own user to see them. And set the permissions for the files in a corresponding way.

  cd
  find * -type d -exec chmod 700 {} \;
  find * -type f -exec chmod 600 {} \;
  

  Using * instead of . excludes the hidden directories and files from these actions.

Test:

Logging in live-only, 'Try Ubuntu', does not give direct access to files saved in Documents. but the default ubuntu live has sudo permissions, and can access these files that way.

ubuntu@ubuntu:/media/ubuntu/casper-rw/upper/home/tester$ ls -l
total 44
drwx------ 2 1000 1000 4096 Jan 24 20:28 Desktop
drwx------ 2 1000 1000 4096 Jan 24 20:58 Documents
drwx------ 2 1000 1000 4096 Jan 24 20:28 Downloads
drwx------ 2 1000 1000 4096 Jan 24 20:28 Music
drwx------ 2 1000 1000 4096 Jan 24 20:28 Pictures
drwx------ 2 1000 1000 4096 Jan 24 20:28 Public
drwx------ 2 1000 1000 4096 Jan 24 20:28 Templates
drwx------ 2 1000 1000 4096 Jan 24 20:28 Videos
-rw------- 1 1000 1000 8980 Jan 24 20:27 examples.desktop
ubuntu@ubuntu:/media/ubuntu/casper-rw/upper/home/tester$ ls -l Documents/
ls: cannot open directory 'Documents/': Permission denied
ubuntu@ubuntu:/media/ubuntu/casper-rw/upper/home/tester$ sudo ls -l Documents/
total 8
-rw-r--r-- 1 1000 1000 7 Jan 24 20:54 hej
-rw-r--r-- 1 1000 1000 6 Jan 24 20:58 hi
ubuntu@ubuntu:/media/ubuntu/casper-rw/upper/home/tester$ cat Documents/hi
cat: Documents/hi: Permission denied
ubuntu@ubuntu:/media/ubuntu/casper-rw/upper/home/tester$ sudo cat Documents/hi
hello
ubuntu@ubuntu:/media/ubuntu/casper-rw/upper/home/tester$ 

Installed Ubuntu in a USB pendrive

• If you want security it is much better to create an installed system in your USB pendrive, installed like into an internal drive (but into a pendrive). See the instructions at the following link:

  How do I install Ubuntu to a USB key? (without using Startup Disk Creator).

• If you wish, you can encrypt it (LVM with LUKS encryption). In that case, do it at the partitioning window during the installation.