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TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure

BH #TED4320U • MFR #D4-320U
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TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure
Key Features
  • 4 x 3.5/2.5" SATA Drive Bays
  • 1 x USB-C 3.2 Gen 2 Port
  • Read Speeds of up to 1016 MB/s
  • Write Speeds of up to 960 MB/s
The TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure can function as a stand-alone storage enclosure or be used an expansion enclosure for TerraMaster NAS devices running TOS 5.1 or above in a compact 1 RU rack-mountable design. Built with four SATA drive bays that can handle 2.5 or 3.5" hard drives and SSDs, the D4-320U delivers read speeds of up to 1016 MB/s and write speeds of up to 960 MB/s when equipped with four SSDs. It connects to your host Windows, Mac, Linux, or TOS system using a 10 Gb/s USB-C 3.2 Gen 2 port that is compatible with USB 3.2 Gen 1, Thunderbolt 3, or Thunderbolt 4.
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TerraMaster D2-320U Overview

The TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure can function as a stand-alone storage enclosure or be used an expansion enclosure for TerraMaster NAS devices running TOS 5.1 or above in a compact 1 RU rack-mountable design. Built with four SATA drive bays that can handle 2.5 or 3.5" hard drives and SSDs, the D4-320U delivers read speeds of up to 1016 MB/s and write speeds of up to 960 MB/s when equipped with four SSDs. It connects to your host Windows, Mac, Linux, or TOS system using a 10 Gb/s USB-C 3.2 Gen 2 port that is compatible with USB 3.2 Gen 1, Thunderbolt 3, or Thunderbolt 4.

Please note that the D4-320 may not be configured as a RAID without the use of third-party software. Plug-and-play connectivity means that no additional drivers are required for use, while three intelligent 40mm cooling fans operate based on system temperature, ensuring that the drives operate within their optimal range.

Please note that the D4-320 does not currently support individual drives larger than 22TB.

Expansion of NAS Storage Space
Based on careful adaptation and optimization by the professional team at TerraMaster, the D4-320U offers seamless connection to the USB interface of TerraMaster NAS. Leveraging the powerful TOS system developed by TerraMaster, users can easily create arrays and storage pools on the D4-320U, effectively expanding the storage space of their NAS to meet growing demands for data. This feature is only applicable to TerraMaster NAS devices running TOS 5.1 or above. Based on this innovative feature, the D4-320U provides users with a more flexible and diverse storage expansion solution.
Intelligent Disk Sleep
The D4-320U supports work mode management by intelligently entering sleep mode along with the computer system. This design not only effectively reduces the working time of the hard drives, minimizing wear on the hard drive motors, but also extends the lifespan of the hard drives themselves. This maximizes efficient storage while also providing peace of mind in terms of protecting hard drive assets.
Safety
To ensure the safety of the device and hard drives, the D4-320U incorporates an advanced power protection design. In the event of users incorrectly connecting an incompatible power source, the device will immediately activate a built-in protection mechanism, effectively preventing damage to the device and hard drives from excessive currents or unstable voltages. This considerate design offers added peace of mind on using the D4-320U, eliminating any concerns about potential losses due to power-related issues.
Automatic Backup
Make scheduled backups of your data with the user-friendly TPC Backupper software. After connecting your device to your computer and installing the client, you can set up tasks to back up folders and disk partitions from your compatible Windows PC to TerraMaster USB devices or NAS storage servers. Compatible with Windows 8, 8.1, 10, and 11 systems, this software supports incremental and differential backup strategies, providing reliable protection to your data.

TerraMaster D2-320U Specs

Key Specs
RAID
No
Number of Bays
4x 2.5"/3.5"
Inputs/Outputs
1x USB-C 3.1/3.2 Gen 2
Drives
RAID
No
General
Number of Bays
4x 2.5"/3.5"
Inputs/Outputs
1x USB-C 3.1/3.2 Gen 2
Media Card Slots
No
PCI Expansion
No
Software
OS Compatibility
Windows
macOS
Linux
Security
Encryption
No
Security Features
No
Electrical
Input Power
100 to 240 VAC, 50 / 60 Hz
Power Consumption
45.5 W (Maximum)
8.1 W (Idle)
PSU
1 x 72 W
Physical
Operating Conditions
32 to 104°F / 0 to 40°C at 5 to 95% Humidity
Storage Conditions
-4 to 140°F / -20 to 60°C at 5 to 95% Humidity
Certifications
CCC, CE, FCC, KC
Cooling
3x 40 mm Fans
Noise Level
26.7 dBA
Dimensions
17.3 x 9.5 x 1.8" / 440 x 241 x 45 mm
Weight
6.0 lb / 2.7 kg
Packaging Info
Package Weight
9.92 lb
Box Dimensions (LxWxH)
22.1 x 14.9 x 4.2"

TerraMaster D2-320U Reviews

See any errors on this page?

Will this device support PCIe 4.0 x4 M.2 SSDs? If ...

Will this device support PCIe 4.0 x4 M.2 SSDs? If not, what?
Asked by: Brian
The TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure does not support or have space for M.2 SSDs. It uses 3.5/2.5" SATA drives.
Answered by: JP A
Date published: 2025-09-25

Is there space in these drive bays for SSDs with ...

Is there space in these drive bays for SSDs with attached heat sinks? Will the unit support that?
Asked by: Brian
No, there is no space in the TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure for SSDs.
Answered by: JP A
Date published: 2025-09-25

Are these drive bays SATA III?

Are these drive bays SATA III?
Asked by: Brian
Yes, the drive bays on the TerraMaster D4-320U 4-Bay USB 3.2 Gen 2 Rack-Mounted Hard Drive Enclosure are SATA III.
Answered by: Michael S
Date published: 2025-09-25
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