move /boot on zfs on root to ext4

# modprobe zfs

# zpool import -a -N -R /mnt

Mount the root pool into /mnt

# zfs mount LP_Pool/ROOT/lp_root

mount -t proc /proc /mnt/proc

mount --rbind /dev /mnt/dev

mount --rbind /sys /mnt/sys

chroot /mnt /bin/bash --login

export ZPOOL_VDEV_NAME_PATH=YES

grub-probe /

sgdisk -p /dev/sdx

#creating

sgdisk -n 1:2048:4095 -c 1:"BIOS Boot Partition" -t 1:ef02 /dev/sdx

#below command will create new partition number "2" of size 3219MB 

sgdisk -n 2:4096:6291456 -c 2:"Linux /boot" -t 2:8300 /dev/sdx

# For  1605 MB

#sgdisk -n 2:4096:3291456 -c 2:"Linux /boot" -t 2:8300 /dev/sdx

mkfs.ext4 /dev/sdx2 and mount it on /newboot

mount -t ext4 /boot/ /newboot/

copy /boot/* to /newboot

rename /newboot to /boot

get UUID of /dev/sdx2 and append to fstab as below:-

UUID=1b1d424c-9fd1-4fd2-aba7-80252f1a8d64 /boot           ext4    defaults        0       2

grub-install /dev/sdx

update-grub2

grub-mkdevicemap

update-initramfs -u -k all

exit from chroot

# zfs unmount -a

# zfs set mountpoint=/ LP_Pool/ROOT/lp_root

# reboot

https://github.com/openzfs/zfs/wiki/Ubuntu-18.04-Root-on-ZFS

https://www.rodsbooks.com/gdisk/sgdisk-walkthrough.html

https://pve.proxmox.com/wiki/ZFS:_Tips_and_Tricks

Boot fails and goes into busybox

If booting fails with something like

No pool imported. Manually import the root pool
at the command prompt and then exit.
Hint: try: zpool import -R /rpool -N rpool

is because zfs is invoked too soon (it has happen sometime when connecting a SSD for future ZIL configuration). To prevent it there have been some suggestions in the forum. Try to boot following the suggestions of busybox or searching the forum, and try ONE of the following:

a) edit /etc/default/grub and add "rootdelay=10" at GRUB_CMDLINE_LINUX_DEFAULT (i.e. GRUB_CMDLINE_LINUX_DEFAULT="rootdelay=10 quiet") and then issue a # update-grub

b) edit /etc/default/zfs, set ZFS_INITRD_PRE_MOUNTROOT_SLEEP='4', and then issue a "update-initramfs -k 4.2.6-1-pve -u"