MOS: A Fresh Take on the NAS Operating System From an Unraid Legend

New NAS operating systems don't come around often. Like, really don't come around often. We've had TrueNAS (and its FreeNAS roots) for over two decades. OpenMediaVault has been plugging along since 2009. Unraid carved out its niche in the mid-2000s. The landscape has been pretty static for years.

So when ich777, one of the most respected names in the Unraid community, quietly releases his own NAS operating system called MOS (Modular Operating System), it's worth paying attention. This isn't some random GitHub project that'll be abandoned in six months. This comes from someone who's spent years building Docker containers, plugins, and kernel drivers that thousands of homelabbers rely on daily.

Let's dig into what MOS actually is, why it exists, and whether it deserves a spot in your homelab.

What Is MOS?

MOS stands for Modular Operating System, though as the developer notes with a bit of humor, "No, it's not an acronym. Or maybe it is." At its core, MOS is a lightweight operating system built specifically for small, energy-efficient home servers.

The system is based on Devuan, which itself is a fork of Debian minus systemd. For those unfamiliar, Devuan uses traditional init systems instead of systemd, resulting in a lighter and more predictable base. It's the kind of foundation that makes sense for a server OS where simplicity and stability matter more than bleeding-edge desktop features.

MOS ships with support for:

Docker - Fully integrated container management
LXC - Linux containers for when you need something closer to a full system
QEMU/VMs - Full virtual machine support (frontend still in development, but the API is nearly complete)

The entire system is wrapped in a modern, clean web interface that handles everything from storage pools to user management to container deployment. And yes, it's all open source under AGPLv3.

Who Built This Thing?

This is where the story gets interesting. ich777 (Christoph) isn't some newcomer to the homelab scene. He's been an absolute workhorse in the Unraid community for years, maintaining over 200 repositories on GitHub. His contributions include:

Dozens of game server Docker containers (ARK, Valheim, Minecraft, you name it)
The Nvidia driver plugin that lets Unraid users use their GPUs for transcoding
DVB driver packages for TV tuners
Coral TPU accelerator drivers
Countless other plugins and utilities

When someone with this track record decides to build their own NAS operating system from scratch, it carries weight. This isn't vaporware or a weekend project. MOS started as a personal solution that ich777 built because he needed something that "just worked, quickly and reliably." When friends started asking to use it, he added a REST API. Then came the web frontend. Eventually, it grew into a full operating system with nearly complete GitHub automation for builds and releases.

Key Features That Stand Out

Storage: mergerfs + SnapRAID by Default

One of the smartest design decisions in MOS is the default storage approach. Instead of forcing you into a specific RAID configuration, MOS ships with mergerfs and SnapRAID built in.

For those unfamiliar with this combo:

mergerfs lets you combine multiple drives into a single unified pool. Your files stay on individual drives (no striping), but you see one big filesystem. Want to add a drive? Just throw it in. Want to remove one? Pull it out and your other files are fine.
SnapRAID provides parity protection, but works at the file level rather than block level. It's perfect for media collections where data doesn't change constantly.

This approach is wildly popular in the homelab community because it's flexible, recoverable, and lets you mix drive sizes without penalty. If a drive dies, you only lose what's on that drive (and can potentially recover it from parity). It's the same philosophy that made Unraid popular, but without the licensing cost.

Additional storage drivers are available through the MOS Hub plugin system, keeping the base installation lean while letting power users add what they need.

Modern REST API and WebSocket Support

Here's where MOS shows its modern design philosophy. The entire system is API-first. The web UI isn't some monolithic application, it's just a client that talks to the MOS backend API.

This means:

Everything you can do in the UI, you can do via API calls
Real-time updates via WebSocket, no constant polling required
Full Swagger documentation at /api-docs on your MOS installation
Easy integration with automation tools, custom scripts, or external dashboards

If you've ever tried to automate tasks on TrueNAS or wished you could script your Unraid setup more easily, you'll appreciate this approach.

Clean, Functional Web Interface

The MOS dashboard provides a real-time view of your system with panels for:

OS details, version info, and uptime
CPU load with per-core utilization and temperature
Memory usage broken down by system, Docker, LXC, and cache
Network traffic per interface
Storage pool capacity and usage
Disk activity and temperatures

The left navigation gives quick access to Disks, Pools, Shares, MOS Hub (for Docker templates), Docker containers, LXC containers, VMs, Users, Web Terminal, and Settings. There's also dark mode support because it's 2025 and we all need that.

Zero Telemetry, Zero Cloud Dependencies

This deserves its own callout. From the official documentation:

"No data is collected. There is no telemetry, no tracking, and no usage reporting of any kind. Everything runs locally and stays fully under your control."

In an age where every piece of software wants to phone home, this commitment matters. Your data stays yours.

How Does MOS Compare to the Competition?

MOS vs TrueNAS

TrueNAS is the heavyweight champion, built around ZFS with enterprise-grade features. It's incredibly powerful but demands ECC RAM (technically recommended, practically expected), lots of memory for ZFS, and a steep learning curve for pool management.

MOS takes the opposite approach. It's designed to run on minimal hardware with just 8GB RAM as the baseline requirement. The mergerfs/SnapRAID combo is far more forgiving than ZFS, letting you add mismatched drives without planning your entire storage strategy upfront.

TrueNAS wins on data integrity guarantees and enterprise features. MOS wins on simplicity and hardware flexibility.

MOS vs Unraid

The comparison to Unraid is inevitable given ich777's background. Both use a similar storage philosophy (pooling drives with parity protection). Both have Docker support with template-based deployments.

Key differences:

Licensing: Unraid requires a license ($59-$129). MOS is free and AGPLv3 open source.
VM Frontend: Unraid has mature VM management. MOS has API support but the frontend is still developing.
Maturity: Unraid has been refined for nearly two decades. MOS is very early stage.
Community: Unraid has a massive ecosystem. MOS is just getting started.

MOS vs OpenMediaVault

OMV is another Debian-based NAS option with a plugin system. It's more mature than MOS but can feel clunky compared to MOS's cleaner interface. OMV doesn't include Docker by default (it's a plugin), while MOS treats containers as first-class citizens.

Both are free and open source. OMV has years of community plugins and documentation. MOS has a more modern architecture but less community support.

Installation: Refreshingly Simple

Getting MOS running is straightforward:

Prepare a USB stick - Format it as FAT32 and set the volume label to "MOS"
Download the latest release - Grab the .zip archive from the GitHub releases page
Extract to the USB stick - No imaging tools needed, just unzip directly to the drive
Boot from USB - Select it in your boot menu and you're off

That's it. No Rufus, no balenaEtcher, no dd commands. Just extract and boot. The system can run directly from USB or be installed to internal storage.

Minimum requirements are reasonable: any x86_64 processor, 8GB RAM, and a network interface. Additional drives are recommended for actual storage pools.

Pros and Cons

The Good

Truly open source - AGPLv3 with no license fees, ever
Built by someone who knows NAS software - ich777's track record speaks for itself
Modern architecture - API-first design with WebSocket support
Flexible storage - mergerfs/SnapRAID lets you grow organically
Clean interface - No clutter, no bloat
No telemetry - Your data stays local
Low resource requirements - Runs well on modest hardware
Docker, LXC, and VMs - All virtualization options in one system

The Not-So-Good

Very early stage - Bugs will happen, and some features are incomplete
VM frontend is work-in-progress - API works, but web UI management is limited
Small community - Less documentation, fewer tutorials, limited forum support
No ZFS (by default) - If you need enterprise-grade data integrity, look elsewhere
Uncertain roadmap - Single developer means features come when they come

Who Should Try MOS?

MOS is ideal for:

Homelab enthusiasts who want to experiment with something new
Self-hosters running primarily Docker-based services
Budget-conscious builders who want NAS functionality without license fees
Developers who appreciate API-first design and want to automate everything
Anyone tired of bloated NAS interfaces who wants something clean and focused

MOS probably isn't right for:

Production environments where stability is critical
Users who need hand-holding - documentation is still sparse
ZFS devotees who want checksumming and self-healing
Anyone who needs mature VM management - for now

The Bottom Line

MOS represents something rare in the NAS world: a genuine new option built from scratch with modern design principles. It's not trying to be TrueNAS or Unraid. It's carving its own path with a focus on simplicity, modularity, and openness.

Is it ready for prime time? Honestly, not quite. The developer is refreshingly transparent about this being early-stage software. But the foundation is solid, the philosophy is sound, and the person behind it has proven they can deliver quality software.

If you're the type who likes getting in early on promising projects, or you've been looking for a free, open-source alternative to Unraid with similar storage flexibility, MOS deserves a spot on a spare USB drive. Just keep backups (you're doing that anyway, right?) and report bugs when you find them.

The NAS landscape hasn't seen a serious new contender in years. MOS might just be the fresh air the homelab community has been waiting for.

Resources

Ready to build your own NAS but need hardware first? Check out affordable servers from Hetzner or Vultr if you want to test MOS in the cloud before committing to local hardware.