Various changes, and added a live-disk config.

config/hardware/lambda.nix

@@ -1,8 +1,13 @@
 { config, lib, pkgs, ... }:
 
-{
+with lib;
+let
+
+in {
   imports = [ <nixpkgs/nixos/modules/installer/scan/not-detected.nix> ];
 
+  system.stateVersion = "21.05";
+
   boot = {
     initrd = {
       availableKernelModules = [
@@ -19,34 +24,62 @@
     };
 
     kernelModules = [ "kvm-amd" ];
-    kernelPackages = pkgs.linuxPackages_latest;
+    kernelPackages = pkgs.linuxPackages.zfs;
+    supportedFilesystems = [ "zfs" ];
 
     loader.grub = {
       enable = true;
       version = 2;
-      device = "/dev/disk/by-label/nixos-root";
+      device = "/dev/disk/by-label/lambda-root";
     };
   };
 
   fileSystems = {
-    "/" = {
-      device = "/dev/disk/by-label/nixos-root";
-      fsType = "btrfs";
+    "/boot" = {
+      device = "/dev/disk/by-label/lambda-boot";
+      fsType = "ext4";
     };
 
-    "/boot" = {
-      device = "/dev/disk/by-label/nixos-boot";
-      fsType = "ext4";
+    "/" = {
+      device = "lambda/transient/root";
+      fsType = "zfs";
+    };
+
+    "/nix" = {
+      device = "lambda/transient/nix";
+      fsType = "zfs";
+    };
+
+    "/var/log" = {
+      device = "lambda/transient/logs";
+      fsType = "zfs";
+      neededForBoot = true;
+    };
+
+    "/home" = {
+      device = "lambda/persistent/home";
+      fsType = "zfs";
+    };
+
+    "/state" = {
+      device = "lambda/persistent/state";
+      fsType = "zfs";
     };
   };
 
-  swapDevices = [{ device = "/dev/disk/by-label/nixos-swap"; }];
+  boot.initrd.postDeviceCommands = lib.mkAfter ''
+    ${pkgs.zfs}/bin/zfs rollback -r lambda/transient/root@blank
+  '';
+
+  swapDevices = [{ device = "/dev/disk/by-label/lambda-swap"; }];
 
   nix.maxJobs = lib.mkDefault 12;
 
   hardware.bluetooth.enable = false;
 
   networking = {
+    hostId = substring 0 8 (fileContents /etc/machine-id);
+
     macvlans = {
       intif0 = {
         interface = "enp3s0f1";