Add some instructions on how to set-up ZFS for use with the custom module

modules/README.md

@@ -0,0 +1,48 @@
+### Setting up ZFS
+
+1. Create three partitions:
+   * Boot
+   * Swap
+   * ZFS
+
+   For example:
+   ```shell
+   sgdisk -n 0:0:+512MiB -t 0:EF00 -c 0:boot $DISK
+   sgdisk -n 0:0:+32GiB -t 0:8200 -c 0:swap $DISK
+   sgdisk -n 0:0:0 -t 0:BF01 -c 0:ZFS $DISK
+   ```
+
+2. Configure swap and boot as usual.
+
+3. Create ZPool:
+   ```shell
+   zpool create -O mountpoint=none -O encryption=aes-256-gcm -O keyformat=passphrase rpool $ZFS_PART
+   ```
+   Leave out `-O encryption=aes-256-gcm -O keyformat=passphrase` if you don't want to fully encrypt the ZFS partition.
+
+4. Create datasets:
+   ```shell
+   zfs create -o mountpoint=legacy rpool/local/root
+   zfs snapshot rpool/local/root@blank
+   zfs create -o mountpoint=legacy rpool/local/nix
+   zfs set compression=lz4 rpool/local/nix
+   zfs create -o mountpoint=legacy rpool/local/cache
+   zfs set compression=lz4 rpool/local/cache
+   zfs create -o mountpoint=legacy rpool/safe/data
+   zfs set compression=lz4 rpool/local/data
+   ```
+5. Mount datasets:
+   ```shell
+   mount -t zfs rpool/local/root /mnt
+   mkdir /mnt/nix
+   mount -t zfs rpool/local/nix /mnt/nix
+   mkdir /mnt/boot
+   mount $BOOT_PART /mnt/boot
+   mkdir /mnt/cache
+   mount -t zfs rpool/local/cache /mnt/cache
+   mkdir /mnt/data
+   mount -t zfs rpool/safe/data /mnt/data
+   ```
+6. Configure Host ID
+
+   Set `networking.hostid` in the nixos config to `head -c 8 /etc/machine-id`.