blog/content/posts/2022-05-09-installing-nixos-on-encrypted-zfs.md

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title = "Installing NixOS on ZFS with encryption"
date = 2022-05-09
tags = ["nixos", "linux", "setup"]
draft = true
toc = true
+++
This is mostly to serve as a reference for how I set up my machine, so I can
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look back on it later. <!--more--> I'll be installing NixOS on my desktop, with
the following specs:
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- CPU: AMD Ryzen 7 3700X
- GPU: NVIDIA GeForce RTX 3080 Ti
- RAM: 80GB
- Storage:
- SSD1: 1TB Samsung SSD 860 (encrypted), which I'm migrating off of
- SSD2: 2TB Crucial MX500 (encrypted), which I'm migrating to
- HDD: 3TB HITACHI HUA72303 (unencrypted), which serves as storage for music
and games.
I already have my [Nix flake][1] setup for my other machines, but of those only
my server runs NixOS. Instead, all my other machines use Arch Linux with just
the Nix package manager installed on top.
[1]: https://git.sr.ht/~mzhang/flake
## Installation Media
Since I'm using two SSDs, I don't bother with flashing the installation media on
a USB stick and rebooting into that. I can just use Nix to get the tools that I
need:
```
nix shell nixpkgs#nixos-install-tools
```
This will get me scripts like `nixos-generate-config` and `nixos-install` which
I'll need for my setup.
## Disk Setup
First, I identified my disks. This can be done using `ls -l /dev/disk/by-id` and
identifying the one corresponding to your disk.
```
export SSD1=/dev/disk/by-id/ata-Samsung_SSD_860_EVO_1TB_[...]
export SSD2=/dev/disk/by-id/ata-CT2000MX500SSD1_[...]
export HDD=/dev/disk/by-id/ata-HITACHI_HUA723030ALA640_[...]
```
Then, using some of the other references out there, I carefully used `sgdisk` to
construct the partition tables. I want to dual boot NixOS with Windows, so I'm
purposefully leaving out around 40% of the disk for that partition. (Note: use
`sgdisk -L` to get the IDs for the `-t` parameter)
```
# Zap the disk
sgdisk --zap $SSD2
# 1: Boot partition
sgdisk -n1:1M:+512M -t1:ef00 $SSD2
# 2: NixOS partition
# Note: bf01 is "Solaris /usr & Mac ZFS"
sgdisk -n2:0:+1000G -t2:bf01 $SSD2
```
We'll let Windows create its own partitions using its installer later.
## ZFS Setup
```
zpool create \
-o ashift=12 `# 2^12 = 4096 sector size, note small o` \
-o autotrim=on \
-O acltype=posixacl `# needed for some things` \
-O atime=off `# turn off access time` \
-O mountpoint=none `# turn off automatic mounting` \
-O compression=lz4 `# sure, why not` \
-O xattr=sa \
-O encryption=aes-256-gcm `# disk encryption` \
-O keyformat=passphrase \
rpool $SSD2-part2
```
It'll prompt for the encryption passphrase now.
```
mkfs.vfat $SSD2-part1
zfs create -o mountpoint=legacy rpool/nixos
```
Mount them:
```
export MNT=/mnt/nixos
mount -t zfs rpool/nixos $MNT
mkdir $MNT/boot
mount $SSD2-part1 $MNT/boot
```
## NixOS Hardware Configuration
```
nixos-generate-config --root $MNT
```
This writes the default configuration along with the results of the hardware
scan. Although it says not to edit the file, this scrapes all of my virtual
network interfaces which I do _not_ want in my general config, so I'll trim it a
bit. Edit the file with:
```
$EDITOR $MNT/etc/nixos/hardware-configuration.nix
```
For the `configuration.nix` file, the following needs to be added somewhere in
the file in order to get ZFS to work:
```
{
boot.supportedFilesystems = [ "zfs" ];
networking.hostId = "<8 random hex digits>";
}
```
Also I chose to use GRUB instead of systemd-boot, so replace the line enabling
systemd-boot with:
```
{
boot.loader.grub.enable = true;
boot.loader.grub.efiSupport = true;
boot.loader.grub.device = "nodev";
}
```
## Install NixOS
At this point I copied this configuration into my flake, so I can use all the
packages that I've previously set up, including home manager.
Run
```
nixos-install --root $MNT --flake flake#attr
```
Done!