Unattended-upgrades broke persistent live media

Question

I made a boot/installation media of Mythbuntu 16.04 by mkusb 10.6.6. I run a persistent live session. Unattended-upgrades started to operate and install e.g. new kernel on the USB flash drive. The consequence was that system ran out of inodes here: /dev/loop0 mounted at /rofs. How to recover?

Answer 1

Upgrades do not work for the kernel in any persistent live system, because the kernel is started before the overlay structure becomes active.

In general it is not a good idea to upgrade a persistent live system completely, like an installed system - you can add new program packages, and you can upgrade a few application programs, where you really need an upgraded version for something to work. And you need regular backups, for example via the system described at https://help.ubuntu.com/community/mkusb/persistent#Backup_and_restore_of_persistent_overlay_data

If you want a generally updated and upgraded system, it is better to

1. either create an installed system, which is suitable to update && dist-upgrade via the command line or automatically.

2. or grab the current 16.04 LTS daily iso file, and create a new persistent live system. You find it via this link: http://iso.qa.ubuntu.com/qatracker/milestones/351/builds. In your case, select a version of Mythbuntu, and you will find a link to the download information. (The 16.04 daily iso files will no longer be updated after 16.04.5 is released.)

I suggest that you save the /home directory in the casper-rw partition (to another drive) and copy it to your new persistent live system (now based on the current daily live iso iso). It will save your tweaks. You must re-install the additional program packages you need manually.

Answer 2

I am surprised that the persistent live system started an automatic security upgrade. I don't think it is caused by the installer (mkusb), because the files controlling those actions are not touched. I tested in an Ubuntu 16.04.1 LTS system, that I left running overnight: It updated & dist-upgraded too. I made a small survey and found:

• This bug affects 16.04 LTS, 16.04.1 LTS and Yakkety.
• Several flavours are affected.
• Lubuntu is not affected.

You find a table of the survey and screenshots at

https://ubuntuforums.org/showthread.php?t=2335669&p=13538805#post13538805

See the corresponding bug report at

https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1619188

-o-

Until this is resolved, it is a good idea to disable unattended-upgrades, but above all, to take regular backups. The following screenshot illustrates where to change 'what to do when there are security updates' in Ubuntu 16.04.1 LTS. Click on it to make it full size and easier to read the text.

Edit: From mkusb 11.0.2 you are given an option to change the default from 'Download and install automatically' to 'Display immediately', which will disable unattended-upgrades. So if you create a persistent live drive with the current version of mkusb, you can avoid this problem 'automatically'.