{ config, pkgs, lib, ... }:
{
  # https://openzfs.github.io/openzfs-docs/Getting%20Started/NixOS/index.html
  # https://nixos.org/manual/nixos/stable/#sec-linux-zfs
  # https://nixos.wiki/wiki/ZFS
  # https://search.nixos.org/options?query=services.zfs

  boot.kernelPackages = lib.mkForce pkgs.zfs.latestCompatibleLinuxPackages;
  boot.supportedFilesystems = [ "zfs" ];
  boot.zfs.forceImportRoot = false;

  # must be set per host
  #   head -c4 /dev/urandom | od -A none -t x4
  # consider the one automatically generated by systemd:
  #   head -c 8 /etc/machine-id
  #networking.hostId = "12345678";

  services.zfs.autoSnapshot.enable = true; # simply runs zfstools
  # default args, can be overriden per-dataset
  services.zfs.autoSnapshot.frequent = 2; # 15 min
  services.zfs.autoSnapshot.hourly = 3;
  services.zfs.autoSnapshot.daily = 4;
  services.zfs.autoSnapshot.weekly = 3;
  services.zfs.autoSnapshot.monthly = 5;

  #services.zfs.autoReplication.enable
  #services.zfs.autoScrub.enable = true;
  #services.zfs.trim.enable = true;

  # the `sharenfs` property generates /etc/exports.d/zfs.exports file, automatically processed by NFS
  # # zfs set sharenfs="-maproot=0:0 -network=192.168.1.0/24" Reidun
  # # zfs set sharenfs="ro=192.168.1.0/24,all_squash,anonuid=70,anongid=70" Meconium
  # # zfs set sharenfs="rw=192.168.1.0/24" Meconium
  services.nfs.server.enable = lib.mkDefault true;
}