TerraMaster D4-320U: Rackmount Direct Attached Storage Enclosure

The TerraMaster D4-320U Direct Attached Storage (DAS) enclosure, featuring four bays and flexible support for 3.5-inch HDDs or 2.5-inch SSDs, is a strategic choice for expanding storage capacity in professional environments. This device is designed for rackmount installation in standard server racks, making it ideal for businesses seeking to expand large archival storage or support existing Network Attached Storage (NAS) systems.

To clarify: Direct Attached Storage (DAS) refers to storage units that connect directly to a single computer or server, typically via a USB cable, offering high performance for local storage needs. In contrast, Network Attached Storage (NAS) systems are dedicated storage devices that connect to a network, allowing multiple users and devices to access data over the network, and often include their own operating system and additional data management features. For more details on the difference between DAS and NAS.

The TerraMaster D4-320U ships diskless, giving users the flexibility to choose their preferred hard drives or SSDs. The device supports four bays, each capable of accommodating 3.5-inch drives with capacities up to 30TB, providing a massive total storage capacity of up to 120TB. The setup process is simple and straightforward; once the drives are inserted, a single USB 3.2 Gen2 cable is connected to the host device (whether a PC, server, or NAS system), and all four drives immediately appear as additional external storage units.

The storage performance largely depends on the type and speed of the installed SSDs or HDDs. Thanks to the high-speed USB 3.2 Gen2 connection, transfer rates of up to 1000 MB/s can be achieved. Tests showed that read and write speeds were very close to the advertised performance of individual Lexar NS100 SSDs used, and almost maxed out when configured in a software RAID 0 array.

It is essential to understand that the D4-320U functions solely as an external hard drive enclosure, not a full-fledged NAS system. It does not include built-in RAID or its own operating system. However, it offers significant flexibility as software RAID can be applied to combine the four drives into one large storage unit, or it can simply be used as additional storage for an existing NAS system.

TerraMaster D4-320U Design: The Ideal Solution for Server Racks

The D4-320U features a rackmount design, making it specifically tailored for businesses and organizations with existing server rack systems, rather than small offices. The installation process is exceptionally easy, as the unit can be mounted directly into the rack. An AC power cable connects to a small adapter that plugs directly into a power source, while a single USB 3.2 Type-C cable connects to the server, NAS system, or any other device for the purpose of expanding storage capacity.

The unit is delivered diskless, providing users with complete flexibility to choose and install HDDs or SSDs that meet their needs. The device supports Seagate Exos Mozaic M drives with capacities up to 30TB, enabling a total storage capacity of up to 120TB. The standard dimensions of the unit are 438 mm wide (without the bracket), 242 mm deep, and 44 mm high, with a weight of 2.7 kg before drive installation.

The four front bays are designed for quick drive loading. A push-release latch reveals a handle, allowing the tray to be pulled out, a 2.5-inch drive to be inserted with a bracket, or a 3.5-inch drive to be installed, and then pushed back in to secure it in place. It is important to note that this enclosure is simple and does not support hot-swapping drives. Each bay has two LED indicators showing drive status.

The unit boasts exceptional build quality, with pre-installed brackets ensuring easy installation and durability. At the rear, three fans operate continuously to keep the device cool, though it should be noted that they may produce some noise.

TerraMaster D4-320U Features: Flexibility and Performance for Storage Expansion

The TerraMaster D4-320U is specifically designed to serve server environments and integrates seamlessly with other TerraMaster devices, such as rackmount NAS arrays. However, the device offers superior flexibility, allowing it to be easily connected to any other NAS system to function as an expandable external storage unit.

A key advantage is the high-speed connection via a single USB 3.2 Gen2 cable that links the enclosure to a NAS system or desktop computer, supporting data transfer rates of up to 10 gigabits per second. Please note that actual speeds depend entirely on the performance of the installed drives.

The enclosure supports SATA drives measuring 2.5 or 3.5 inches, with capacities up to 30TB per drive, allowing for a total storage capacity of 120TB. Being merely an external storage enclosure (DAS), it offers wide compatibility with multiple operating systems, including Windows, macOS, and Linux.

Although the system is designed to operate in server rooms, TerraMaster has incorporated an intelligent fan management and airflow system. This system adjusts fan speeds to achieve an optimal balance between noise level and internal temperature, contributing to improved drive performance. The unit features Plug-and-Play operation, requiring minimal setup. When connected directly to a computer, the drives appear as individual storage units, and the same applies when connected to a NAS system.

TerraMaster D4-320U Performance: High Speeds and Flexible Use

During extensive testing, the TerraMaster D4-320U was connected to both a studio setup and a desktop PC equipped with an ASUS Prime Z890-P Wi-Fi motherboard, in addition to being tested with a MacBook Pro. Storage performance was also evaluated by connecting it to a NAS system as an external storage unit, where it was recognized instantly.

It was noted that the unit was noisier than most other quiet devices, with the fans constantly running and emitting a faint but noticeable hum. This fan noise could be a nuisance in quiet work environments, especially during tasks like video editing. Therefore, it is advisable to place the device in a separate room or connect it to a NAS system over the network when using it for large archival storage.

When installing four 1TB Lexar NS100 SSDs and connecting the unit to a Windows PC via USB 3.2, excellent transfer speeds of approximately 520 MB/s per drive were recorded, matching the advertised limits for SSDs. After creating a software RAID, file transfer speeds increased to around 930 MB/s.

After about a month of intensive daily use, the system continued to operate highly efficiently without any issues, confirming its effectiveness as a fast and direct solution for accessing massive amounts of storage without the delays often associated with pulling files from a NAS system. However, two downsides were noted: its large size (being designed for racks, it’s not ideal for desktop use) and the constant fan noise, which remained noticeable even when the unit was elevated from the surface.

The D4-320U was later moved to another room and connected as additional storage for a NAS system. It was immediately recognized and effortlessly increased the existing 16TB capacity by an additional 4TB without any configuration problems. Its transfer speeds even surpassed those of the system's internal storage, demonstrating seamless and efficient integration.

After two months of continuous use, the D4-320U became an integral part of the network. The SSDs were faster than the NAS system's internal drives, significantly accelerating file transfers. This feature makes it an ideal choice for photographers and video editors who require high speeds.

One of the system's main strengths is its great flexibility, as the unit ships empty, giving the user the freedom to configure settings according to their needs. Different drives can be mixed and matched, although matching sizes is preferred when using software RAID. If RAID is not used, greater flexibility is available; for example, two 30TB HDDs and two 1TB SSDs can be used. The choice depends entirely on individual requirements and budget.

This device represents an excellent storage solution for anyone who owns a server rack and wishes to increase storage capacity without having to change the internal drives of their NAS system. This solution allows you to invest incrementally, adding larger drives as needed, avoiding the need to overhaul your entire system at once, and helping to maintain simplicity and affordability.

Final Verdict: Comprehensive Review of the TerraMaster D4-320U

The D4-320U is clearly designed for commercial use and enterprise environments, and this device will be particularly appealing to users who already own a server rack or are considering installing one in a studio or office. The device features a standard rackmount form factor, making installation extremely simple; all it requires is mounting it next to the server or NAS system and connecting a single USB cable.

For users who do not own racks but prefer the idea of a four-bay Direct Attached Storage (DAS) solution, the D4-320U can be connected directly to their computer. However, it should be noted that the continuous fan noise may be a nuisance in a quiet workspace, and the device will still require proper mounting.

Once the device is installed in the rack and set up, it becomes easy to use and requires little monitoring. If connected to your NAS system, you can configure and access it with the flexibility you desire. The device's flexibility stands out significantly, as you can install large capacity hard drives, fast SSDs, or even a mix of both, and completely configure it to suit your specific needs.

If your NAS system is experiencing a shortage of storage space, the D4-320U represents a logical and effective solution. A single USB cable provides enormous expansion capacity, and if your NAS's operating system supports it, the integration is seamless and at a much lower cost than purchasing a completely new NAS system.

Despite its advantages, there are still some minor issues. The continuous fan noise was the most bothersome aspect. Even with small and efficient SSDs, the fans always ran and were clearly audible. This may not be an issue in a naturally noisy server room, but it could become annoying if the unit is close to the user.

Additionally, while I appreciate the simplicity of the single USB port, I wished it were possible to daisy-chain units together when reaching maximum capacity (120TB), which is only possible with Thunderbolt technology. With only one USB 3.2 port, your NAS system needs to support multiple connections if you plan to expand further, a feature that TerraMaster's rackmount devices support, but it goes beyond my current setup.

In conclusion, the device demonstrated remarkable ease of use as a rackmount solution. Once installed, it was easily accessible, fast performing, and simple to manage. If I were to set up a permanent rack in my studio, I would seriously consider using a device like the TerraMaster D4-320U as a storage expansion solution.

Although this solution may not be the most suitable for very small businesses, it is worth considering for storage needs in environments requiring large capacity and reliable performance.