How to Build a NAS? | Start With Two Same-Size Drives

For the full breakdown, see our best DIY NAS Case guide.

Once you understand how to build a NAS, the project stops sounding like a data-center job. You use a normal desktop or small-form-factor PC with an x86_64 CPU, install TrueNAS SCALE on its own SSD, add two matching data drives, and then let the software handle the heavy lifting. This page covers the parts that matter, the software to choose, and the setup mistakes that waste money.

Build a NAS: The Hardware That Matters

TrueNAS SCALE’s current hardware guide, version 25.04, starts from a short specification: an x86_64 CPU, 8 GB of RAM, a 20 GB SSD for the operating system, and two identically sized drives for the first storage pool. Those four choices shape every other buying decision.

The full details are in the official TrueNAS SCALE 25.04 hardware guide, so check it before ordering anything. If the case is the last part you need, our tested roundup of the best DIY NAS cases sorts the options by drive bays and cooling so you can match a case to a two-drive or four-drive plan.

Which NAS Software Should You Use?

Use TrueNAS SCALE when the box might run apps, containers, or virtual machines; the hardware guidance in this article is written specifically for that operating system family. It is also a strong choice for plain file sharing because it is built on ZFS.

Choose the software before you buy hardware. TrueNAS SCALE expects direct access to your disks, so a simple motherboard with its own SATA ports handles most home builds cleanly. That approach keeps the setup close to the tested path and lets you move into containers or VMs later without rebuilding the machine.

The Setup Order That Works

Install in this order: put TrueNAS SCALE on the boot SSD, create one storage pool from the two data drives, then add shares and turn on services from the web UI. Skipping that order is where configs get confusing.

1. Build the machine with the boot SSD and both data drives connected.
2. Download the TrueNAS SCALE installer, write it to a USB stick, and boot from that stick.
3. When the installer asks for a target drive, select the dedicated SSD. Do not install the OS on a drive you plan to use for storage, because that target gets erased.
4. Log in to the TrueNAS SCALE web interface and create a storage pool using the two identically sized data drives.
5. Set up shares and enable services, such as SMB, from the web UI. Once those shares appear on your network, the build is done.

Three mistakes cause most of the frustration:

• Buying one large drive and expecting redundancy. The minimum pool uses two identically sized drives. If you want one drive to fail without losing files, choose a mirror when you create the pool.
• Undersizing the boot device. The 25.04 baseline is 20 GB. A bigger SSD is inexpensive and gives you room for extra boot environments.
• Hiding drives behind a RAID controller. ZFS wants to see each disk directly. If your controller has an HBA or passthrough mode, use it.