[Bug 1988299] Re: Can't upgrade from 20.04 to 22.04 due to extreme space requirement for /boot

[George]

> How did you remove the other kernel versions?
I just ran `apt remove` on the relevant kernel packages.
Maybe synaptic has some guardrails to prevent a user from configuring the system to only have a single kernel installed?

> What was your initial initramfs compression setting?
Mine was initially lz4. 
This is the default for Ubuntu 20.04 installations I think.
It is actually not a good choice from a space perspective - it achieves a compression ratio even lower than gzip.
Rather, it was chosen because it is very quick, which speeds up boot times quite a bit.
Both lzma and xz should offer substantial reductions in the footprint of installed kernels in /boot, but this comes at the expense of longer boot times. 
This is actually moot though, since the upgrade tool for 22.04 overwrites the compression setting (if you let it - I did to no ill effect).

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https://bugs.launchpad.net/bugs/1988299

Title:
  Can't upgrade from 20.04 to 22.04 due to extreme space requirement for
  /boot

Status in ubuntu-release-upgrader package in Ubuntu:
  Triaged

Bug description:
  I'm attempting to upgrade from 20.04 to 22.04 and my installation uses
  full disk encryption, so I have a separate partition for /boot.

  The size of the /boot partition was set by the installer for 20.04 (to
  704 MiB) and I currently have 329 MiB free after removing old kernels
  with apt autoremove:

    $ df -h /boot
    Filesystem      Size  Used Avail Use% Mounted on
    /dev/sdb2       704M  324M  329M  50% /boot

  When attempting to upgrade to 22.04 it fails with:

    The upgrade has aborted. The upgrade needs a total of 787 M free
    space on disk '/boot'. Please free at least an additional 442 M of
    disk space on '/boot'. You can remove old kernels using 'sudo apt
    autoremove' and you could also set COMPRESS=xz in
    /etc/initramfs-tools/initramfs.conf to reduce the size of your
    initramfs.

  So it claims to need more space than the total size of the partition
  (so presumably no amount of compressing initramfs will be enough!),
  which as noted above is the default size for /boot chosen by the 20.04
  installer.

  Another instance of this issue has been raised here: https://askubuntu.com/q/1423156/57751
  --- 
  ProblemType: Bug
  ApportVersion: 2.20.11-0ubuntu27.24
  Architecture: amd64
  CasperMD5CheckResult: skip
  CrashDB: ubuntu
  CurrentDesktop: ubuntu:GNOME
  DistroRelease: Ubuntu 20.04
  InstallationDate: Installed on 2020-04-25 (859 days ago)
  InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
  NonfreeKernelModules: nvidia_modeset nvidia
  Package: ubuntu-release-upgrader (not installed)
  ProcVersionSignature: Ubuntu 5.15.0-46.49~20.04.1-generic 5.15.39
  Tags:  focal dist-upgrade
  Uname: Linux 5.15.0-46-generic x86_64
  UpgradeStatus: Upgraded to focal on 2022-08-31 (1 days ago)
  UserGroups: adm cdrom dip docker lpadmin lxd plugdev sambashare sudo
  _MarkForUpload: True

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