zedenv GRUB Plugin

zedenv - ZFS boot environment manager - GRUB plugin

Install

Install zedenv then zedenv-grub.

Setup

One of two types of setup needs to be used with grub.

Boot on ZFS - separate grub dataset needed.
Separate partition for kernels

Boot on ZFS (Recommended)

To use boot on ZFS:

A grub dataset is needed. It should be mounted at /boot/grub.
org.zedenv.grub:bootonzfs should be set to yes
Individual boot environments should contain their kernels in /boot, which should be part of the root dataset.

To convert an existing grub install, set up the grub dataset, and mount it. Then install grub again.

zfs create -o canmount=off zroot/boot
zfs create -o mountpoint=legacy zroot/boot/grub
mount -t zfs zroot/boot/grub /boot/grub

# efi
mount ${esp} /boot/efi
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB

# or for BIOS
grub-install --target=i386-pc /dev/sdx --recheck

If you get:

/dev/sda
Installing for i386-pc platform.
grub-install: error: failed to get canonical path of `/dev/ata-SAMSUNG_SSD_830_Series_S0VVNEAC702110-part2'.

A workaround is to symlink the expected partition to the id

ln -s /dev/sda2 /dev/ata-SAMSUNG_SSD_830_Series_S0VVNEAC702110-part2

Separate Partition for Kernels

An example system on Arch Linux with a separate partition for kernels would be the following:

Boot partition mounted to /mnt/boot.
The directory containing kernels for the active boot environment, /mnt/boot/env/zedenv-${boot_env} bind mounted to /boot.
The grub directory /mnt/boot/grub bindmounted to /boot/grub
org.zedenv.grub:bootonzfs should be set to no with zedenv set org.zedenv.grub:bootonzfs=no

What this would look like during an arch Linux install would be the following:

zpool import -d /dev/disk/by-id -R /mnt vault

mkdir -p /mnt/mnt/boot /mnt/boot
mount /dev/sda1 /mnt/mnt/boot

mkdir /mnt/mnt/boot/env/zedenv-default /mnt/boot/grub
mount --bind /mnt/mnt/boot/env/zedenv-default /mnt/boot
mount --bind /mnt/mnt/boot/grub /mnt/boot/grub

genfstab -U -p /mnt >> /mnt/etc/fstab

arch-chroot /mnt /bin/bash

In chroot

export ZPOOL_VDEV_NAME_PATH=1

grub-install --target=x86_64-efi --efi-directory=/mnt/boot --bootloader-id=GRUB
grub-mkconfig -o /boot/grub/grub.cfg

An example generated grub.cfg looks like:

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Arch Linux' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-a1b916c0819a1863' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_gpt
        insmod fat
        set root='hd0,gpt1'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1  B11F-0328
        else
          search --no-floppy --fs-uuid --set=root B11F-0328
        fi
        echo    'Loading Linux linux ...'
        linux   /env/zedenv-default/vmlinuz-linux root=ZFS=vault/sys/zedenv/ROOT/default rw  quiet
        echo    'Loading initial ramdisk ...'
        initrd  /env/zedenv-default/initramfs-linux.img
}

Converting Existing System

Create a backup.

cp -a /boot /boot.bak

Unmount /boot, and remount it at /mnt/boot.

mkdir -p /mnt/boot
mount /dev/sdxY /mnt/boot

Then you want to move your current kernel to /mnt/boot/env/zedenv-${boot_env_name}

mkdir /mnt/boot/env/zedenv-default
mv /mnt/boot/* /mnt/boot/env/zedenv-default

Move the grab directory back if it was also moved (or don't move it in the first place).

mv /mnt/boot/env/zedenv-default/grub /mnt/boot/grub

Now bindmount the current kernel directory to /boot so that everything is where the system expects it.

mount --bind /mnt/boot/env/zedenv-default /boot

Same thing with the grub directory

mount --bind /mnt/boot/grub /boot/grub

Now everything is back to appearing how it looked originally, but things are actually stored in a different place.

---

You're also probably going to want to update your fstab, if you're using Arch you can use genfstab, which requires arch-install-scripts.

genfstab -U -p /

You'll need to add the output to /etc/fstab.

This is what an example looks like.

# /dev/sda1
UUID=B11F-0328          /mnt/boot       vfat            rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro       0 2

/mnt/boot/env/zedenv-grub-test-3        /boot           none            rw,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro,bind   0 0
/mnt/boot/grub          /boot/grub      none            rw,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro,bind   0 0

Post Setup

After install, run zedenv --plugins, you should see grub.

Set bootloader config, options can be queried with zedenv get --defaults:

$ zedenv get --defaults
PROPERTY                    DEFAULT    DESCRIPTION
org.zedenv:bootloader                  Set a bootloader plugin.
org.zedenv.systemdboot:esp  /mnt/efi   Set location for esp.
org.zedenv.grub:boot        /mnt/boot  Set location for boot.
org.zedenv.grub:bootonzfs   yes

Set the bootloader so it doesn't have to be declared on every usage with the -b flag.

# zedenv set org.zedenv:bootloader=grub

zedenv will do its best to decide whether or not you are booting off of an all ZFS system, but it can also be set explicitly with org.zedenv.grub:bootonzfs=yes.

Any values you have set explicitly will show up with zedenv get.

Now create a new boot environment:

# zedenv create linux-4.18.12
# zfs list
NAME                       USED  AVAIL  REFER  MOUNTPOINT
zroot                     2.43G  36.1G    29K  none
zroot/ROOT                2.42G  36.1G    29K  none
zroot/ROOT/default        2.42G  36.1G  2.42G  /
zroot/ROOT/linux-4.18.12     1K  36.1G  2.42G  /
zroot/data                9.36M  36.1G    29K  none
zroot/data/home           9.33M  36.1G  9.33M  legacy

You may want to disable all of the grub generators in /etc/grub.d/ except for 00_header and the zedenv generator 05_zfs_linux.py by removing the executable bit.

johnramsden / zedenv-grub