UniFi UNAS Pro 4 Review: Where Does It Fit in the Lineup?

Ubiquiti continues to expand the UniFi storage lineup—and with more options comes a more nuanced decision-making process. Today, we’re taking a deep dive into the UNAS Pro 4, a 1U, 4-bay rackmount NAS with dual NVMe cache support.

After spending time unboxing, configuring, and testing it in our lab, one big question kept coming up:

Where exactly does the UNAS Pro 4 fit between the UNAS Pro and the UNAS Pro 8?

Let’s walk through the hardware, the setup experience, the software, and—most importantly—the real-world use cases.

First Impressions & Hardware Overview

As expected from UniFi, the packaging is clean and professional. The UNAS Pro 4 includes:

• Rack rails
• Rack ears and mounting hardware
• Power cable
• 1U 4-bay chassis
• Dual NVMe cache support (via internal access door)
• Two 10Gb SFP+ ports
• 1Gb management port
• UniFi RPS redundant power interface
• Three internal (non-serviceable) fans

The NVMe installation is straightforward. If you purchase Ubiquiti’s NVMe drives, they include the required sled and tool. You can also buy the sled separately (around $19) and install your own NVMe drives.

From a form factor standpoint, it’s similar to the 4-bay UNVR chassis—compact, rack-friendly, and clean.

Setup Experience: Fast and Frictionless

Deployment was exactly what we’ve come to expect from UniFi:

1. Rack the unit
2. Open the UniFi app
3. Device auto-detects
4. Rename and configure
5. Done in about two minutes

No drama. No complicated initialization process.

Storage Configuration & RAID Options

In our configuration:

• 4x 8TB HDDs
• 2x 1TB NVMe drives

The RAID options include:

• RAID 5
• RAID 6
• RAID 10

We chose RAID 10 for performance and redundancy.

That resulted in:

• 32TB raw capacity
• 16TB usable storage

Yes—half the raw storage is lost in RAID 10. RAID 5 would provide 24TB usable, but RAID 10 delivers better performance.

And this is where the first big question arises:

With only four bays, are we giving up too much capacity at this performance tier?

NVMe Cache Configuration

The dual NVMe drives can be configured in:

• RAID 0 (Read-only cache) – Maximum performance, no redundancy
• RAID 1 (Read/Write cache) – Redundant, half the usable cache

We chose RAID 1 for redundancy and write acceleration.

This setup improves:

• Frequently accessed file reads
• Write performance (data lands in cache before writing to HDD)

However, it’s important to understand the workload profile.

If you're storing:

• Plex libraries
• Large media archives
• Cold storage files
• Backup repositories

You may not see major read performance gains from NVMe caching.

But if you're running:

• Shared templates
• Databases
• Frequently edited files
• Active creative workloads

The NVMe cache can significantly improve responsiveness.

UniFi Drive 4.0 Software

UniFi’s storage software continues to evolve rapidly.

Notable features include:

🔹 UniFi Endpoint

• Maps the NAS as a network drive automatically
• Simplifies SMB setup
• Integrates with UniFi Identity

🔹 Health & Monitoring

• Drive health
• Temperature metrics
• Fan control (Balanced mode is impressively quiet)
• Usage and throughput analytics

🔹 Backup Options

You can back up to:

• Another UNAS
• Google Drive
• Dropbox
• Wasabi
• OneDrive
• Amazon S3
• Backblaze

Additionally, Office 365 backup support is rolling out:

• OneDrive (live)
• Exchange, Teams, SharePoint (coming soon)

This rapid feature expansion is one of the most compelling reasons to stay in the UniFi ecosystem. The platform today looks very different than it did just two months ago—and it will likely continue improving over the device’s 5–6 year lifespan.

The Big Question: Pro 4 vs Pro vs Pro 8

Let’s break it down.

UNAS Pro 4 – $499

• 4 bays
• Dual 10Gb SFP+
• NVMe cache support
• 8GB RAM
• 2GHz ARM processor
• Single RAID group

Strengths:

• Faster processor than original Pro
• NVMe acceleration
• Compact 1U
• Same price as UNAS Pro

Limitations:

• Only 4 bays
• Limited expansion
• 10Gb difficult to saturate with 4 spinning disks

UNAS Pro (7-Bay Classic)

• 7 bays
• 10Gb connectivity
• No NVMe cache
• 8GB RAM
• 1.7GHz processor

This remains a very strong contender.

For many environments—including our own editors working daily in Adobe Premiere—the original Pro is “fast enough.”

The biggest advantage?

More drive bays.

And when it comes to storage devices, capacity often wins.

UNAS Pro 8 – $799

• 8 bays
• Dual redundant hot-swappable power supplies
• 16GB RAM
• More expansion headroom
• 2U form factor

For professional environments, the additional $300 buys:

• Future-proofing
• More RAM
• More bays
• Redundant power
• Better 10Gb utilization potential

If you're deploying in a business environment expected to last 5–6 years, the Pro 8 is hard to ignore.

Real-World Performance Perspective

Here’s the reality:

To truly saturate 10Gb networking, you generally need 6–7 spinning disks in a performant RAID configuration.

With only four drives, the Pro 4 may not fully utilize its 10Gb capability unless heavily leveraging NVMe cache.

So the decision comes down to workload:

Choose UNAS Pro 4 if:

• You’ll never exceed 4 bays
• You need faster small-file performance
• You rely heavily on active, frequently accessed files
• You value NVMe acceleration

Choose UNAS Pro if:

• You want maximum storage per dollar
• You don’t need NVMe
• Your workload is primarily large file storage
• You want more expansion flexibility

Choose UNAS Pro 8 if:

• You’re deploying in a professional environment
• You want redundant power
• You expect growth
• You want higher sustained throughput
• You care about long-term scalability

So Where Does It Fit?

Originally, I wasn’t overly excited about the UNAS Pro 4. But at $499, matching the Pro’s price, it becomes more interesting.

There is a specific slice of users who:

• Want better performance
• Won’t exceed four drives
• Benefit from NVMe cache
• Don’t need Pro 8-level scalability

But if it were my money?

For home use, I still lean slightly toward the UNAS Pro (7-bay) for storage flexibility.

For business deployments, I lean toward the UNAS Pro 8 for longevity and redundancy.

The Pro 4 sits in that narrow middle ground—very capable, very fast in the right workloads, but highly dependent on use case.

Final Thoughts

UniFi is doing something interesting here.

Much like the Protect camera lineup, we’re seeing increasingly granular choices. The differences aren’t massive—they’re nuanced.

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