Ubuntu – How to create enough space for Steam on a persistent live USB


I'm a newcomer to Ubuntu (due to the upcoming Windows 7 EOL) and I'm trying to test Ubuntu on a bootable USB stick, but I cannot get Steam to run because of a lack of space. How should I distribute the space on my USB so that Steam & a game can be tested?

I have used Rufus 3.8 to create a bootable USB stick containing Ubuntu 19.10 Eoan Ermine with a 16GB persistent partition.* I have been able to download the Steam installer. After installing, Steam downloaded 350MB of updates. Unfortunately, it has been unable to complete the update, saying that it needs 250MB more space. This appears to be correct, as Ubuntu's 'Files' utility say that the "casper-rw" partition only has 85 MB left.

The 'Disks' utility provides a different set of numbers. It says my 32GB** stick has a 14GB FAT Ubuntu partition (with 11GB free), a 17GB ext3 casper-rw partion, and 11GB free.

I am guessing that I need to make the persistent partition larger, but several points make me wonder whether I've done something else wrong. I am surprised that the Steam installer and runtime, without any games, have used up 16GB, because an installation is only supposed to require 5 GB. I am also puzzled that there is 11GB free in the Ubuntu partition: I thought that was supposed to be a read-only partition pretending to be a live CD, so there should not be any free (writable) space at all. Given that it's there, should I be trying to install Steam to somewhere other than the default location? Or should I try using Lubuntu or Xubuntu to make the OS smaller? Surely there's some way to squeeze Ubuntu and Steam onto a 32GB stick?!

*I know Steam says you should use 18.04LTS, but Rufus requires 19.10 for persistent USBs.

**Let's not quibble about GB or GiB here as it's probably irrelevant.

Best Answer

Solution with a persistent live USB pendrive and Ubuntu 18.04 LTS

This method should work for you because mkusb is designed to work with all current versions of Ubuntu.

  • If you have two USB pendrives, you can make a live-only system i Windows using Rufus with 18.04.1 or 18.04.3 LTS. This could be in a smaller and/or slower drive.

  • Boot into this live drive.

  • Install mkusb into it (live-only, but it will survive until its task is done and you reboot).
  • Create a persistent live drive in the other bigger and/or faster USB pendrive. mkusb will create a persistent live drive with a partition for persistence and you can select 100% of the available drive space for persistence.
  • Boot into the persistent live system
  • Install Steam and enjoy :-)


  • You can use an SSD in an external box and connect via USB 3 or eSATA. This will make a very fast system, almost like it were an internal drive.
  • You can create an installed Ubuntu system in a USB drive, pendrive or any other kind of external drive (e.g. SSD).
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