{
  fileSystems = {
    "/mnt/hdd" =
      { device = "/dev/disk/by-label/NixNAS_HDD";
        fsType = "btrfs";
        options = [ "discard" ];
      };
    "/mnt/ssd" =
      { device = "/dev/disk/by-label/NixNAS_SSD";
        fsType = "btrfs";
        options = [ "discard" ];
      };
  }
}