Those who want full control over their storage are best off replacing their QNAP NAS operating system with TrueNAS, gaining a full-fledged ZFS platform in return. This works effortlessly on a powerful device like the TVS-h874T, but how do you keep the way back to QTS open?
QNAP ships its devices with QTS or, on high-end models, with the ZFS-based QuTS hero. Both operating systems do their job, but they tie you to the manufacturer’s ecosystem: you are dependent on QNAP apps.
TrueNAS, developed by iXsystems, offers an open source alternative that runs on ZFS. The latter is a file system known for its data integrity, snapshots, compression, and replication. Those who manage their own infrastructure and don’t want to be chained to a single vendor will find TrueNAS an attractive way out. The NAS hardware remains; only the operating system changes.
x86 is the first requirement
The main reason why a device like the QNAP TVS-h874T can be converted lies in the processor. This NAS runs on a twelfth-generation Intel Core i7. TrueNAS Scale is built on a Linux kernel and expects exactly that x86 architecture. A NAS with an ARM processor, like many entry-level models, is immediately disqualified: TrueNAS simply won’t run on it.
In addition to the processor, peripherals also play a role. The 2.5GbE network ports, the Thunderbolt 4 controller, and the M.2 slots of the QNAP TVS-h874T are recognized by the Linux kernel. If in doubt, it’s best to look up the exact chipsets beforehand, but with this class of devices, most of the hardware works immediately.
The HDMI port makes the difference
A TrueNAS installation proceeds just like on a regular PC: you plug a USB stick with the installer into the device, enter the BIOS, change the boot order, and go through the installation steps on a screen. For this, you need a monitor and a keyboard.
The TVS-h874T features an HDMI output (4K at 30 Hz). You connect a monitor and a keyboard, and you have full access to the BIOS and the graphical interface. It is precisely that HDMI port that makes the entire operation simple and reliable.
NAS models without a display output are a completely different story. A device like the QNAP TS-h973AX has no HDMI or VGA port, and then you’re stuck. You can’t see the BIOS, you can’t follow the installation, and you don’t know what’s happening on the screen. Those who try anyway must resort to cumbersome tricks: installing the boot SSD in a regular PC first and then transferring it, navigating the BIOS blindly from memory, or hoping the device automatically boots from USB. Some rackmount models still offer a 3.5mm console port as an alternative, but that is not a comfortable workflow. In short: no display output, no smooth conversion. That is the rule that determines whether your NAS is suitable.
How the installation works in broad strokes
The operation itself is intentionally not rocket science. You write the TrueNAS Scale image to a USB stick, connect a monitor and keyboard, and start the device while holding down the BIOS key (usually Del or F12 on QNAP, shortly after the beep). In the BIOS, you set the USB stick as the primary boot source.
The installer then asks which drive TrueNAS should be placed on. This is the critical moment: you choose a separate boot drive — on the TVS-h874T, an M.2 2280 NVMe SSD in one of the two internal slots. You leave your data disks and the internal QNAP module untouched. A small 128 or 256 GB SSD is more than enough as a boot drive; you keep your large bays free for the actual storage pool.
After installation, you permanently set the boot order to that SSD in the BIOS, remove the USB stick, and restart. TrueNAS boots up, and from that point on, you manage everything via the web interface. You won’t need the keyboard-and-monitor combination after that.
The DOM keeps your way back open
A frequently asked question: does the QNAP OS disappear permanently? The answer is reassuring. QTS and QuTS hero are stored on an internal DOM (Disk on Module) on QNAP devices: a small flash memory located on the motherboard. As long as you install TrueNAS on a separate M.2 SSD and deliberately do NOT select that DOM during installation, the original operating system remains intact.
In practice, this means: if you ever want to go back to QTS, you simply change the boot order to the DOM in the BIOS. The device will then boot QTS again. This way back is particularly relevant for warranty issues. If the device needs repair, you switch back to QTS first. Physically, nothing has changed in the hardware, and QNAP support simply sees its own system.
Should the DOM ever become damaged, QNAP offers a safety net through its firmware recovery procedure. Using the Qfinder Pro utility and a USB boot image, you can make the DOM usable again and reinstall the firmware. It’s a messier path than a simple boot switch, but it exists.
One caveat: once you have formatted your data disks to ZFS, you lose the original QNAP RAID configuration and the data on them. QTS will run again, but without your old storage pool. A reliable backup remains the basic rule here as well.
What you give up
It’s important to be honest. By switching to TrueNAS, you lose the entire QNAP software offering: the QTS app store, Hybrid Backup Sync, the mobile apps, and the integrated features that attract many users to QNAP in the first place. You trade ease of use for control and flexibility. Furthermore, TrueNAS manages the disks via ZFS software RAID, and you no longer use QNAP‘s hardware RAID. For many professional scenarios, this is an advantage, but it remains a conscious break from the original setup.
Finally: although you aren’t physically changing anything on the device, it’s best to check your warranty terms before you start. The hardware remains intact, but you are moving outside the manufacturer’s intended use. For those who know what they are doing and keep a solid backup handy, the gain in freedom far outweighs those disadvantages.