Basic NixOS Virtualbox Setup

Commands

# Original: https://nixos.wiki/wiki/NixOS_on_ZFS#How_to_install_NixOS_on_a_ZFS_root_filesystem

# Make sure to enable EFI support in VB. Settings -> System -> Enable EFI

# Add the zfs filesystem to the install environment:
nano /etc/nixos/configuration.nix

## ---8<-------------------------8<---
  boot.supportedFilesystems = [ "zfs" ];
## ---8<-------------------------8<---

nixos-rebuild switch

# Load the just installed ZFS kernel module
modprobe zfs

sgdisk     -n3:1M:+512M -t3:EF00 /dev/disk/by-id/scsi-SATA_disk1
sgdisk     -n1:0:0      -t1:BF01 /dev/disk/by-id/scsi-SATA_disk1

zpool create -o ashift=12 \
      -O atime=off -O canmount=off -O compression=lz4 -O normalization=formD \
      -O mountpoint=/ -R /mnt \
      rpool /dev/disk/by-id/scsi-SATA_disk1-part1

# Create the filesystems
zfs create -o mountpoint=none rpool/root
zfs create -o mountpoint=legacy rpool/root/nixos
zfs create -o mountpoint=legacy rpool/home
zfs set compression=lz4 rpool/home 

# Mount the filesystems manually
mount -t zfs rpool/root/nixos /mnt

mkdir /mnt/home
mount -t zfs rpool/home /mnt/home

# Create the FAT Disk for EFI booting
mkfs.fat -F32 /dev/disk/by-id/scsi-SATA_disk1-part3

mkdir /mnt/boot
mount /dev/disk/by-id/scsi-SATA_disk1-part3 /mnt/boot

# Generate the NixOS configuration, as per the NixOS manual
nixos-generate-config --root /mnt

# Now edit the generated hardware config:
nano /mnt/etc/nixos/hardware-configuration.nix

## ---8<-------------------------8<---
# This is what you want:

  fileSystems."/" =
    { device = "rpool/root/nixos";
      fsType = "zfs";
    };

  fileSystems."/home" =
    { device = "rpool/home";
      fsType = "zfs";
    };

  fileSystems."/boot" =
    { device = "/dev/disk/by-uuid/2222-2222";
      fsType = "vfat";
    };
## ---8<-------------------------8<---

# configuration.nix needs an adjustment:
nano /mnt/etc/nixos/configuration.nix

## ---8<-------------------------8<---
# This is some more of what you want:
  networking.hostId = " # generate a hex value for this
  boot.supportedFilesystems = [ "zfs" ];
## ---8<-------------------------8<---

# Ready to go!
nixos-install