NixOS install with ZFS

Notes on how I installed NixOS using ZFS filesystems on a laptop

Based a lot on

Target system

My target system, which I call “moth”, is a Lenovo X1 Carbon Thinkpad Generation 1, with UEFI BIOS, Core i7-3667U 2.0 GHz, 8 GB memory.

The BIOS is configured to boot first off a USB drive if found, and to boot only UEFI.

Install media

On Aug 27, 2020, I went to the NixOS download page and downloaded the “Graphical live CD, 64-bit Intel/AMD” image as nixos-plasma5-20.03.2849.feff2fa6659-x86_64-linux.iso.

I plugged in a USB3 thumb drive (SanDisk 64GB drive, way overkill but it was handy), used lsblk to verify that it was /dev/sda, and copied the install image to it:

sudo if=nixos-plasma5-20.03.2849.feff2fa6659-x86_64-linux.iso of=/dev/sda bs=1M

Boot the installer

When that finished successfully, I plugged the USB thumb drive into my target laptop and powered it up. Since it’s configured to boot first off a USB drive, I didn’t need to do anything special for it to boot into the NixOS graphical installer.


I used the networking widget in the lower right status bar to get the laptop onto my local network with access to the Internet.

Set up filesystems

I opened a Konsole window and used that for most of the rest of this. I worked out the following commands by repeatedly editing and trying a script, which is why there are commands at the top to clean up things possibly left over from previous runs.

I set DISK to the “by-id” name of my hard drive:


I started by wiping the partitions using an instruction from

sgdisk --zap-all $DISK

I followed these instructions on how to partition and set up:

# I DID NOT create partition 2 since I don't need legacy (BIOS) boot
# Partition 2 will be the boot partition, needed for legacy (BIOS) boot
# sgdisk -a1 -n2:34:2047 -t2:EF02 $DISK

# If you need EFI support, make an EFI partition:
sgdisk -n3:1M:+512M -t3:EF00 $DISK

# Partition 1 will be the main ZFS partition, using up the remaining space on the drive.
sgdisk -n1:0:0 -t1:BF01 $DISK

# Create the pool. If you want to tweak this a bit and you're feeling adventurous, you
# might try adding one or more of the following additional options:
# To disable writing access times:
#   -O atime=off
# To enable filesystem compression:
#   -O compression=lz4
# To improve performance of certain extended attributes:
#   -O xattr=sa
# For systemd-journald posixacls are required
#   -O  acltype=posixacl
# To specify that your drive uses 4K sectors instead of relying on the size reported
# by the hardware (note small 'o'):
#   -o ashift=12
# The 'mountpoint=none' option disables ZFS's automount machinery; we'll use the
# normal fstab-based mounting machinery in Linux.
# '-R /mnt' is not a persistent property of the FS, it'll just be used while we're installing.
zpool create -O mountpoint=none -O atime=off -O compression=lz4 -O xattr=sa -O acltype=posixacl -o ashift=12 -R /mnt rpool $DISK-part1

# Create the filesystems. This layout is designed so that /home is separate from the root
# filesystem, as you'll likely want to snapshot it differently for backup purposes. It also
# makes a "nixos" filesystem underneath the root, to support installing multiple OSes if
# that's something you choose to do in future.
zfs create -o mountpoint=none rpool/root
zfs create -o mountpoint=legacy rpool/root/nixos
zfs create -o mountpoint=legacy rpool/home

# Mount the filesystems manually. The nixos installer will detect these mountpoints
# and save them to /mnt/nixos/hardware-configuration.nix during the install process.
mount -t zfs rpool/root/nixos /mnt
mkdir /mnt/home
mount -t zfs rpool/home /mnt/home

# If you need to boot EFI, you'll need to set up /boot as a non-ZFS partition.
mkfs.vfat $DISK-part3
mkdir /mnt/boot
mount $DISK-part3 /mnt/boot