Migrate bootable zfs pool from zsys to sys (FreeBSD 14)

migrate_bootable_zfs_pool.sh

#!/bin/sh

# ada3 new drive where migration intended
gpart add -t efi -s10G -lEFI /dev/ada3
gpart add -t freebsd-swap -s64G -lSWAP /dev/ada3
gpart add -t freebsd-zfs -lSYS /dev/ada3


zfs snapshot -r zsys@full          # create snapshot in source pool
zfs list -t snapshot               # check
zfs destroy -r zsys/usr/obj@full   # remove useless zfs point
mkdir /mnt/sys
zpool create -d -o altroot=/mnt/sys sys /dev/gpt/SYS   # create destination pool and mount it to /mnt/sys
zfs send -R --skip-missing zsys@full | zfs receive -vF sys  # transfer data
zfs destroy -r zsys@full   # destroy snapshot from source pool

# to get FS tree work
zpool export sys
zpool import -o altroot=/mnt/sys -f sys

zpool get all sys # get all pool properties to check.
zfs create -o mountpoint=/usr/obj sys/usr/obj   # restore zfs point for obj
zpool set bootfs=sys/ROOT/default sys           # make `sys` pool bootable

mount -t msdosfs /dev/ada3p1 /mnt/sys/boot/efi     # mount EFI partition to mounted `sys` pool
# create UEFI boot record to boot from this device
# efibootmgr will create correctly path in BIOS NVRAM. It will start paths from efi media (see `gpart list /dev/ada3`).
# BootOrder  : 0002, 0000, 0001, 0003
# Boot0002* kingston.bvgm.su HD(1,GPT,0011d507-7f3c-11ef-ae74-001b21d2a5b3,0x28,0x1400000)/File(\EFI\BOOT\loader.efi)
#                               ada3p1:/EFI/BOOT/loader.efi (null)
efibootmgr --activate --create --loader /mnt/sys/boot/efi/EFI/BOOT/loader.efi --label kingston.bvgm.su

# to unmount new `sys` pool before reboot
umount /mnt/sys/boot/efi
zpool export sys