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After upgrading from 18.04 to 20.04, grub does not boot to latest kernel (and ZFS is broken)

cn flag
alci

On a remote server (only access via ssh after booted), I am having troubles after upgrading from 18.04LTS to 20.04.3LTS:

  • system reboot on old rescue kernel:

  • and zfs is not working anymore (so all my lxd containers are away for now...)

    $ uname -r 4.19.62-mod-std-ipv6-64-rescue

    $ zpool info The ZFS modules are not loaded. Try running '/sbin/modprobe zfs' as root to load them.

    $ /sbin/modprobe zfs
  modprobe: FATAL: Module zfs not found in directory /lib/modules/4.19.62-mod-std-ipv6-64-rescue

The new kernel is present in /boot:

ll /boot/
total 75287
drwxr-xr-x  5 root root     1024 févr.  6 21:36 ./
drwxr-xr-x 23 root root     4096 févr.  4 06:52 ../
-rw-r--r--  1 root root   237940 janv. 13 18:00 config-5.4.0-97-generic
drwxr-xr-x  2 root root     1024 nov.  24  2018 efi/
drwxr-xr-x  6 root root     1024 févr.  6 21:36 grub/
lrwxrwxrwx  1 root root       27 févr.  6 21:05 initrd.img -> initrd.img-5.4.0-97-generic
-rw-r--r--  1 root root 58416425 févr.  6 21:36 initrd.img-5.4.0-97-generic
lrwxrwxrwx  1 root root       27 févr.  6 21:13 initrd.img.old -> initrd.img-5.4.0-97-generic
drwx------  2 root root    12288 nov.  28  2019 lost+found/
-rw-------  1 root root  4757200 janv. 13 18:00 System.map-5.4.0-97-generic
lrwxrwxrwx  1 root root       24 févr.  6 21:05 vmlinuz -> vmlinuz-5.4.0-97-generic
-rw-------  1 root root 13660416 janv. 13 18:04 vmlinuz-5.4.0-97-generic
lrwxrwxrwx  1 root root       24 févr.  6 21:13 vmlinuz.old -> vmlinuz-5.4.0-97-generic

/etc/default/grub says GRUB_DEFAULT=0

Running update-grub says:

Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/50-cloudimg-settings.cfg'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.4.0-97-generic
Found initrd image: /boot/initrd.img-5.4.0-97-generic
The ZFS modules are not loaded.
Try running '/sbin/modprobe zfs' as root to load them.
Some pools couldn't be imported and will be ignored:
The ZFS modules are not loaded.
Try running '/sbin/modprobe zfs' as root to load them.
The ZFS modules are not loaded.
Try running '/sbin/modprobe zfs' as root to load them.
The ZFS modules are not loaded.
Try running '/sbin/modprobe zfs' as root to load them.
Found Ubuntu 20.04.3 LTS (20.04) on /dev/sda2
done

Where does this "rescue" kernel come from ? and how can I boot to latest kernel (hopefully with ZFS ??) ?

64
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zfs
cn flag
alci
The problem was due to my hosting company (Kimsufi). The machine was set to netboot on a custom kernel and not from disk...
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freezed avatar
cn flag
freezed
How did you install a ZFS root on Kimsifi?
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cn flag
alci
In fact it's not a ZFS root. Root is on ext4, but I made a partition that I added to my zfs pool after the installation. This partition (most of the disk) is used by lxd to handle its containers.
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freezed avatar
cn flag
freezed
Ah ah… I had a workaround to set up a zfs root on SYS… not finished yet but I hope it works (-;
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avatar Ubuntu
cn flag
alci

Finally working. The problem was not an Ubuntu one: my hosted server (Kimsufi) was set to netboot on a custom kernel and not on disk. Kimsufi support helped me sort this out.

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