Comment 0 for bug 1960089

Summary:

We propose to increase the LVM /boot partition to 2.0 GB. This provides the space needed so advanced users can use best practice to manage up to 3 kernel flavors. The current /boot partition on 20.04 and 22.04 is limited to just 705M, which allows only 3 concurrent kernels before filling and sometimes locking the system (each image set takes 180M total; 4 x 180 = 720M > 705M).

Reasoning:

Best practice recommends users keep at least two version of each kernel flavor in the /boot directory. If a user has 3 kernel flavors installed (e.g. oem, generic-hwe, and lowlatency-hwe), then one needs to reserve room for 2 x 3 = 6 kernels.

The system needs the headroom of at least two additional kernels during any automated clean-up process due to package removal scheduling. I propose to also reserve room for 2 additional kernels as a safety measure. Thus the total recommend available space should accommodate 10 kernels.

Each kernel file set takes up 180M in the /boot partition when used with Nvidia driver modules. These files include initrd.img, system.map, and vmlinuz. With future kernel and module growth, this may surpass 200M soon. Therefore, we suggest planning for 200M for each kernel.

We therefore request a total LVM /boot partition size of 10 image x 200M = 2.0 GB.

Other Considerations:

When unattended-upgrades works correctly (which does not yet employ best practice), we have seen users with just a single kernel flavor over-fill their /boot partitions. This is because unattended-upgrades can retain up to 4 kernels, while the /boot partition is only large enough for 3. I am currently working with others to improve the unattended-upgrades algorithm to use best practice.

The installer could allow users to resize the /boot partition during installation. In this case, we highly recommend a 2.0 GB default for the reasons outlined above.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity (not installed)
ProcVersionSignature: Ubuntu 5.14.0-1011.11-oem 5.14.17
Uname: Linux 5.14.0-1011-oem x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Fri Feb 4 14:53:36 2022
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/kubuntu.seed only-ubiquity quiet splash oem-config/enable=true ---
InstallationDate: Installed on 2020-06-10 (604 days ago)
InstallationMedia: Kubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)