Installing fnOS in English: Step-by-Step from a Chinese-Only Official Guide
Compatibility data on this site last refreshed 2026-11-03 · reading time ~3 min
fnOS's official help center (help.fnnas.com) is written in Chinese only — the product site has English pages, but the installation walkthrough does not. Community threads show western users machine-translating screenshots to get through the installer. This guide is the English version of the official steps, with the menu labels you will actually see on screen.
What you need before starting
- A mainstream x86 machine (Arm builds exist as a public beta for Rockchip-class boards). A wired network connection is REQUIRED — the installer does not support Wi-Fi-only machines.
- One drive to install the system onto (see rules below) plus your storage drives.
- A USB stick of 16 GB or more for install media.
- A monitor and USB keyboard for the installation (mouse optional).
Step 1 — Download the ISO
Get the installer image from the official download page (fnnas.com, Download section, fnOS). Write it to the USB stick with Rufus (Windows) or balenaEtcher (any OS); once the write finishes you can set the stick aside until you boot the NAS.
Step 2 — BIOS settings
Two things to check in BIOS before installing. First, disable Secure Boot — if it stays on, the installer stops with a warning (the message translates to: 'Installation is not supported in the current mode. Please disable Secure Boot in BIOS and retry'). Second, note your board's boot-menu hotkey — F2, F7, F8, F10, F11, F12, Esc or Delete depending on the board.
Step 3 — Boot and choose an install mode
Plug in the USB stick, power on, use the boot-menu hotkey and pick the USB device. The installer menu offers 'Graphical Install' (recommended, graphical wizard) and 'Rescuing Install' (fallback — if the graphical wizard errors out, reboot and choose this instead).
Step 4 — Pick the system disk and partition sizes
- Select the drive for the SYSTEM. The OS installs to one single drive — this becomes the system disk.
- System partition size: the installer suggests 64 GB when the disk is big enough (the official recommendation; on VMs you can shrink it).
- Swap size: pre-computed from your RAM — accept the default unless you have a reason not to.
- Minimum viable system disk: 8 GB (per Fnnas staff on the forums) — space on the system disk beyond the system partition is usable for apps and files, so a larger SSD is the practical choice.
- Confirm the format warning: the selected system disk will be wiped entirely (Alt+O to confirm).
Step 5 — Network, reboot, first login
After installation, the network screen appears: DHCP is detected automatically; if your NIC has no DHCP you set the IP manually (confirm with Alt+S). Reboot (Alt+O), remove the USB stick, and note the IP address shown on the console. From here the NAS is headless: browse to http://
Step 6 — Put your data drives in
With the system running, add your storage drives and create storage spaces from the storage manager. fnOS supports ext4, Btrfs and ZFS pools with several RAID shapes, and — as covered in our fnOS drive guide — imposes no whitelist: any SATA/NVMe drive the machine detects can join a pool. Pick NAS-class CMR drives with rated workloads; the rankings on this site (built from four vendors' official compatibility lists) are a solid proxy for proven choices.
Common failure quick-reference
- Stuck at 'not supported in current mode' → disable Secure Boot in BIOS.
- Graphical install crashes → reboot, choose 'Rescuing Install'.
- No network in installer → Wi-Fi-only machines are unsupported; plug in Ethernet.
- Small 8-16 GB Optane/oddball SSD as system disk → works (8 GB minimum) but 64 GB+ is recommended.
- U.2 enterprise NVMe invisible → known fnOS gap as of late 2025; prefer standard M.2 NVMe.
Quick answers
Can I install fnOS without reading Chinese?
Yes — this guide translates every screen you will meet. The key labels: 'Graphical Install' (recommended), 'Rescuing Install' (fallback), the 64 GB system partition default, and the Alt+N / Alt+O / Alt+S confirm keys.
Does fnOS have an English interface?
The official site ships English product pages and the international push is underway, but the help center remains Chinese-only and historical builds were Chinese-first. Check the current release notes for interface language options on your build.
What is the minimum disk size for fnOS?
8 GB is the stated minimum for the system disk (per Fnnas staff). The installer recommends a 64 GB system partition when the disk allows; leftover space on the system disk is usable for apps and files.
Can fnOS install over Wi-Fi?
No — installation requires a wired NIC. Wi-Fi-only machines are explicitly unsupported for setup (this may change in later releases).
Do I need a separate system disk for fnOS?
Strongly recommended but not required. The system lives on exactly one drive; putting it on its own small SSD keeps your storage pool independent and survives system-disk failures cleanly.
Check your exact model
Compatibility is per machine and per part number. Pick your model for its full official drive list: