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I keep filling up /boot with old kernels, at which point nixos-rebuild switch --upgrade will download a bunch of derivations only to eventually fail when installing the new kernel (or initrd) because there is insufficient space on /boot.

One option is to run nix-collect-garbage -d, but that can be extremely slow and can result in needing to download the newly downloaded versions all over again.

Sometimes deleting old kernels seems to help (until /boot fills up again), whereas other times, manually picking a few generations to delete from ls /nix/var/nix/profiles/system-??-link has worked better.

Is there a better approach to deal with /boot filling up? (Particularly for when I want to upgrade and use the new system right away.)

aij
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1 Answers1

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There is a longstanding bug report about this problem when /boot fills up. The situation has improved, but reading through all the comments takes a while, so I will attempt to summarize.

If you are using GRUB, set boot.loader.grub.configurationLimit = 42; (or pick a better number depending on how much space you have in /boot) so that older kernels will be automatically cleaned up. The existing old kernels will be cleaned up on the next nixos-rebuild switch, though you may need to manually delete some first, since the install-grub.pl script will first attempt to copy the new kernels before deleting old ones.

If you are using systemd-boot (formerly Gummiboot), as of NixOS 19.03 (thanks domenkozar), set boot.loader.systemd-boot.configurationLimit = 42; (or pick a suitable number depending on how much space you have in /boot), and the next nixos-rebuild switch should automatically clean up old kernels.

Note that you will want to run nix-collect-garbage eventually, before (or when) /nix fills up. This can also be set to run automatically by setting nix.gc.automatic = true and related options.

aij
  • 203