Skip to main content
TERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount | USB 3.2 Gen2 10Gbps, Type-C External USB Storage, Compact Chassis, Hot Swappable Plug and Play (Diskless)
TERRAMASTER

TERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount

Bottom line: The TERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount: USB 3.2 Gen2 10Gbps; up to 1,016MB/s with four SATA HDDs installed; main trade-off: no RAID or array support — handles individual disks only.

Check price on Amazon

As an Amazon Associate, SpecPicks earns from qualifying purchases. Full disclosure →

Check price on Amazon → Compare to similar external storage

By , Founder & Editor-in-Chief · Listing data updated

Mike Perry — Hardware researcher since 2014. For external drives and portable storage, synthesises manufacturer specs and independent reviews rather than first-hand lab testing. Core beat: GPU performance across gaming, rendering, and local-LLM inference.

Pros & Cons

Pros

  • ✓ USB 3.2 Gen2 10Gbps; up to 1,016MB/s with four SATA HDDs installed
  • ✓ Compact 1U rackmount, 241mm deep (50% shorter), no rails needed
  • ✓ Fits four 3.5"/2.5" SATA drives, 30TB each, 120TB max total
  • ✓ Driver-free plug and play on Mac, Windows and Linux
  • ✓ Hot-swappable bays; ships with USB-C-to-C and USB-A-to-C cables

Cons

  • ✗ No RAID or array support — handles individual disks only
  • ✗ Pool/array creation requires a TerraMaster NAS on TOS 5.1+
  • ✗ Single-drive read caps near 510MB/s, far under 4-drive speed

Related Products

Other products in this category you may like:

SpecPicks Verdict

SpecPicks scored TERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount using a rating × review-volume × price-fit model applied to published specs and reviews across the external storage category. TERRAMASTER's external storage lineup sits within the broader category mid-tier; price and specs are the deciding factors over brand loyalty here. Judge it on the specification table and the price rather than on sentiment: check the figures that decide your use case, then put it side-by-side with two or three close alternatives in the Compare tool before clicking through.

Common buyer scenarios for external storage of this kind: matching it to an existing build, replacing a failing part, or upgrading from a previous-generation equivalent. Check the spec table below against your current setup — particularly socket / form-factor / power-rating fields — and confirm compatibility on the retailer's listing before purchase. Prices and stock are set by the retailer and may have moved since this page was last updated.

Key Features

  • Compact Design for Seamless Deployment: The D4-320U hard drive enclosure (a DAS, NOT a NAS) redefines convenience with its miniaturized 1U rackmount form factor. Measuring just 241mm (9.5 inches) in depth, 50% shorter than traditional chassis and weighing 3.2kg, this sleek enclosure fits effortlessly into standard server racks without the need for rails, simplifying installation. Its space-efficient design maximizes room utilization in data centers, storage closets, stairwells, or offices, making it a suitable choice for small businesses and SOHO users seeking centralized storage solutions
  • High Speed Data Transmission: The D4-320U HDD enclosure adopts USB 3.2 Gen2 protocol for high-speed data transmission up to 10Gbps. With 4 hard drives installed, the read/write speed can reach up to 1,016MB/s (SATA III HDD 8TB x 4). With one hard disk installed, the read speed can reach 510MB/s (SATA III HDD 1TB SSD x 1)
  • Super-large Storage Space: The D4-320U direct attached storage can support up to six 3.5 inch and 2.5 inch SATA HDD, as well as 2.5 inch SATA SSD, with a maximum capacity of 30TB per drive, providing users with up to 120TB (30TB x 4) of storage space. Note that the D4-320U does not support arrays and only works with individual disks
  • Expandable NAS Integration: Optimized for TerraMaster NAS devices running TOS 5.1 or higher, the D4-320U external HDD enclosure connects via USB to expand storage pools and create arrays through the robust TOS system. This feature makes it a powerful companion for users looking to scale their NAS capacity with ease
  • Plug and Play, Highly Compatible: The D4-320U USB storage is a plug-and-play device that does not require drivers to work. It is highly compatible with MAC, Windows, and Linux operating systems. It has a USB Type-C interface and comes with two USB cables (1 x USB type C-C cable, 1 x USB type A-C cable). The device is compatible with various computer interfaces, including USB 4.0, USB 3.2, USB 3.1, USB 3.0, Thunderbolt 5, Thunderbolt 4, and Thunderbolt 3
  • Hot Swappable Functionality: The enclosure features hot-swappable drive bays that allow you to replace or add hard drives without powering down the system, ensuring continuous operation and minimizing downtime during maintenance or upgrades

Full Specifications

BrandTERRAMASTER
Weight3.2kg
MaterialMetal
Unit Count4 Count
ConnectivityUSB
Model NumberD4-320U
CompatibilityMac, Linux
Built-In MediaPower Adapter, Quick Installation Guide, USB Cable
Mfr Part NumberD4-320U
Hardware PlatformWindows, Mac, Linux
Compatible DevicesWindows, Mac, Linux
Data Transfer Rate10 gigabits_per_second
Enclosure MaterialMetal
Hardware InterfaceUSB 3.2 Gen 2
Warranty Description2 Years
Hard Disk Form Factor3.5 inches
Connectivity TechnologyUSB
Item Dimensions L x W x H9.5"L x 17.3"W x 1.8"H
Supported Devices Quantity4
Full listing titleTERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount | USB 3.2 Gen2 10Gbps, Type-C External USB Storage, Compact Chassis, Hot Swappable Plug and Play (Diskless)

Ready to buy?

TERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount | USB 3.2 Gen2 10Gbps, Type-C External USB Storage, Compact Chassis, Hot Swappable Plug and Play (Diskless) is listed on Amazon. Price, availability, shipping and returns are set by Amazon and its sellers — check the listing for current terms. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.

Check price on Amazon →

Related External Storage

Keep exploring SpecPicks

Other buying guides

Browse the catalog

Editorial

More guides & deep dives from the SpecPicks archive

Browse all articles & guides →

More reviews from the SpecPicks archive

Browse all reviews →

Earliest SpecPicks reviews

Browse full archive →
TERRAMASTER D4-320U Hard Drive Enclosure 4Bay 1U Rack Mount | USB 3.2 Gen2 10Gbps, Type-C External USB Storage, Compact Chassis, Hot Swappable Plug and Play (Diskless)
View on Amazon →