In my previous article, I described how to install Ubuntu on a ZFS mirror and boot it using ZFSBootMenu.

This time, the goal is more ambitious: build a proper four-disk NAS where both the operating system and user data live on a single ZFS RAIDZ2 pool, while still being able to boot the machine after losing one or even two physical disks.

I also wanted to avoid a dedicated boot SSD.

This guide installs the control plane for a small home Kubernetes cluster on an x86_64 Ubuntu NAS. Raspberry Pi 5 machines will join it as worker nodes in the next part of the series. The NAS remains the only k3s server and does not run ordinary application workloads.

Target environment: Ubuntu Server 26.04 LTS on x86_64 and k3s v1.36.2+k3s1. Validate the procedure on the NAS before changing this note to Tested on.

This guide turns one Ubuntu 26.04 LTS server with a ZFS pool into a small LAN-only NAS. Samba, Cockpit, and the 45Drives management plugins run together in an Incus system container. Garage provides an S3-compatible API from a Docker container on the host.

Keeping Samba and its management interface in the same system container gives Cockpit direct access to the Unix users, groups, Samba password database, and service it manages. It avoids synchronizing /etc/passwd, smb.conf, or passdb.tdb between application containers.

This guide deploys a small VPN gateway on a public Ubuntu virtual machine. Traefik is the only container that publishes host ports:

• TCP 80 and 443 for HTTPS and Let’s Encrypt;
• UDP 51820 for WireGuard;
• WireGuard UI and the Traefik dashboard are available only over HTTPS.

This setup does not require a separate router or port forwarding. The virtual machine must have a public IP address, and its cloud firewall must allow incoming TCP 80, TCP 443, and UDP 51820 traffic.

Forcing an ext4 Filesystem Check on the Next Reboot with tune2fs

Sometimes you need to verify an ext4 filesystem, but the filesystem is mounted and cannot safely be repaired online. This is especially common when the filesystem is the root filesystem, such as /dev/md0 mounted as /.

Running fsck directly on a mounted filesystem is not a safe way to repair it:

sudo fsck -n -f /dev/md0

The -n option makes it read-only, so it will not fix anything. Also, because the filesystem is mounted, the result may be noisy or misleading. For a real repair check, fsck must run before the filesystem is mounted, usually during boot.

Display the host architecture

uname -m
x86_64

Let’s try run image with arm64. We’ve got an error

docker run --rm -t arm64v8/ubuntu uname -m
WARNING: The requested image's platform (linux/arm64/v8) does not match the detected host platform (linux/amd64/v3) and no specific platform was requested 
exec /usr/bin/uname: exec format error

Install the qemu packages