booting nixos from lvm on top of mdadm

9 Apr 2012

what is this?

since i might require such an setup more often i post it here, so i don’t forget it (see [1]).

this guide works great for fdisk+mdadm+LVM but it did not work for parted lately using ubuntu server. i don’t know why, maybe because of the raid controller?

in case someone removes the commands from the nixos wiki, here are the commands again:

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1

pvcreate /dev/md0
vgcreate myvolgrp /dev/md0
lvcreate -L 1G -n boot myvolgrp
lvcreate -L 5G -n system myvolgrp

mkfs.ext4 -n boot /dev/myvolgrp/boot
mkfs.ext4 -n system /dev/myvolgrp/system

mount -L system /mnt
nixos-option --install

cat /etc/nixos/configuration.nix
  { mountPoint = "/";
  { mountPoint = "/boot";

advantages of this setup

  • no special partition required either something like /dev/sda1 or /dev/sdb1 where /boot would be placed on
  • LVM can be used for anything
  • still mdadm is below, which is a good thing

reminds me though that i should check if /etc/nixos/configuration.nix is capable of installing grub in several partitions already. usually it is only installed in /dev/sda given by this example:

boot.loader.grub = {
  # Use grub 2 as boot loader.
  enable = true;
  version = 2;
  # Define on which hard drive you want to install Grub.
  device = "/dev/sda"; # here is only one partition given


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