Installing Debian on a USB stick for a Terramaster NAS

I recently bought a basic NAS for home use. The NAS is a nice Terramaster F2-425, which is a very basic RAID1-only NAS with a decent CPU and 2.5Gb network. Terramaster allows users to either use its custom Linux-based TOS or install any other operating system supported by the x86_64-based platform. Note that this model does not mount any NVME unit for the OS, as for the F2-424.

Common choices include TrueNas, Proxmox, or any other Linux-based distribution. My choice has been a plain Debian stable distribution because I do not have special requirements and prefer a lightweight CLI-only solution over a dashboard. The F2-425 does not have NVME cards, only regular HDDs/SSDs. However, when installing an independent OS, as in my case, you can immediately use an external USB stick for the system, and dedicate HDDs to data. The unit even has a tiny (264MB) internal USB stick for installing TOS, but I simply used a decent 16GB SanDisk thumb drive. The clear advantage is the possibility of having the base system and data perfectly separated, and multiple copies of the stick for safety.

Of course, the installation of such a system can be done without using the Debian installer at all, so I'm describing here how to perform such an installation for my future reference and for other geeks. Of course, you need a running Linux system with debootstrap installed. The process involves partitioning the stick in GPT mode, installing the base system and EFI, and configuring the system to finalize a bootable system with the necessary software to connect the NAS to the network, including OpenSSH.

Note that the 2.5 Gb Ethernet is a RealTek, so a firmware blob (firmware-realtek package on Trixie) is required to properly work with that. Alternatively, another of the USB ports could also be used to add a wireless connection. The OS stick could be simply mounted on the internal port, but it requires opening the chassis for that and using a tiny stick.

At power-on, the internal TOS dongle automagically boots up, so connecting an HDMI display and a keyboard is required to change the setup to boot the Debian EFI image on the stick. On F2-425, press the <F12> key to access the AMI setup and change boot priorities. There are always slight differences among AMI BIOS setups, so it is required to find the right key to access settings and change boot options.

Let's consider /dev/sde as the name of the USB stick device on the host where it will be prepared. A GPT partition can be created via GNU parted, as follows:

parted /dev/sde 	# to create EFI and root primary partition
partprobe --summary /dev/sde
sfdisk -l /dev/sde
mkfs.vfat -F 32 /dev/sde1
mkswap /dev/sde2
mkfs.ext4 /dev/sde3

Once done, installing the base system is immediate.

mount /dev/sde3 /mnt
mount /dev/sde1 /mnt/boot/efi
debootstrap trixie /mnt

mount -o bind /dev /mnt/dev
mount -t devpts devpts /mnt/dev/pts
mount -t proc proc /mnt/proc
mount -t sysfs sysfs /sys /mnt/sys
mount -t tmpfs run /mnt/run

cp /etc/apt/sources.d/debian.sources /mnt/etc/apt/sources.d/.
cp /etc/resolv.conf /mnt/etc/.

echo "nas" > /mnt/etc/hostname
sed -i -e 's/localhost$/localhost\n127.0.0.1\tnas/' /mnt/etc/hosts

rootfs=$(blkid /dev/sde | grep TYPE=\"ext4\"|awk '{print $2}'|cut -d\" -f2)
vfat=$(blkid /dev/sde|grep TYPE=\"vfat\"|awk '{print $2}'|cut -d\" -f2)
swap=$(blkid /dev/sde|grep TYPE=\"swap\"|awk '{print $2}'|cut -d\" -f2)

cat >/mnt/etc/fstab <<EOF
UUID=$rootfs / ext4 noatime,errors=remount-ro 0 1
UUID=$vfat /boot/efi vfat noatime,umask=0077 0 1
UUID=$swap none swap sw 0 0
EOF

chroot /mnt
apt update
apt upgrade -y
apt install grub-efi-amd64 linux-image-amd64 ssh \
        firmware-realtek xfsprogs rsync \
 	mdadm  parted smartmontools htop ntp unattended-upgrades sudo
useradd -m -G sudo -s /bin/bash -C 'Your Name' your_username 
passwd your_username
apt install tzdata locales
dpkg-reconfigure locales
grub-install --target=x86_64-efi --force-extra-removable /dev/sde
update-initramfs -u
apt clean
exit # leave the chroot
umount /mnt/run
umount /mnt/sys/firmware/efi/efivars
umount /mnt/sys
umount /mnt/proc
umount /mnt/dev/pts
umount /mnt/dev

Note that required HDDs can be easily installed later. I manually configured the two disks with GNU parted for a GPT Linux RAID partition. After booting with the stick, a simple install of the md array support suffices. Typically, the USB stick runs as /dev/sdd

sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1
mkfs.xfs /dev/md0
mkdir /data
data=$(blkid /dev/md0|grep TYPE=\"xfs\"|awk '{print $2}'|cut -d\" -f2)
echo "UUID=$data /data xfs defaults 1 1" >>/etc/fstab

In order to allow shutting down by pressing the power button, it is required to configure systemd-logind as follows.

sed -i -e 's/^#HandlePowerKey=poweroff'/HandlePowerKey=poweroff/ \
       -e 's/^#HandlePowerKeyLongPress=ignore/HandlePowerKeyLongPress=ignore/ \
    /etc/systemd/logind.conf

systemctl restart systemd-logind.service

It could also be a good idea to stop the periodic auto-scan on the RAID volume for big disks, which can take ages to run.

sed -i -e 's/^AUTOCHECK=true/AUTOCHECK=false/' /etc/default/mdadm
systemctl restart mdmonitor.service

The network configuration depends definitively on the type of connection used and the home network configuration. In my case, the NAS uses a static IPv4 address, so it can be configured through ifupdown, and it is only necessary to correctly write the /etc/network/interfaces for the enp1s0 Realtek 2.5Gb Ethernet interface. Not that it requires a non-free firmware blog to run.

After the initial syncing, a series of software to better manage the NAS can be installed, but that is optional and can be the subject of a different post. For sure, for better convenience, a copy of the USB stick with the complete configuration is a good idea, to allow a fast recovery in case of failures.