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Part of Western Digital’s My Cloud Business NAS lineup, the DL4100 is getting long in the tooth, but that doesn’t mean it’s ready for retirement. You can buy it as a barebones, driveless enclosure or in 8TB and 12TB filled prepopulated versions, with our unit shipping with a pair of WD Red 4TB drives and the other two bays left free. Drives are fitted in well-engineered slide-out caddies, making it easy to remove any problem drives and fit new ones.

There’s nothing too exciting about the DL4100’s design, but it’s sturdy and well-executed – not to mention the only NAS on test with a two-line LED display, which is always useful for quick alerts and messages. Connectivity is strong, though, with two USB 3 ports split front and rear, plus a USB 2 port at the back. With dual Gigabit Ethernet ports, you’re covered for link aggregation or a connectivity failure, and WD gives you two power supply inputs, so that it’ll keep running with a spare PSU should the main one die. Just watch out for the noise levels; it starts off making a racket and makes quite the hum even when that dies down.

The DL4100’s biggest strength is its software. Rather than go for a desktop-style interface, WD has opted for a control panel interface where different elements handle different functions, with a bar at the top providing shortcuts to the homepage, users, shared folders, apps, cloud sync, backup, storage and soon. It also has better app support than the similar TeraStation 3220, including DLNA Media Server features, a WordPress server, home automation and more. And while it’s not quite as versatile as Synology’s software, WD’s My Cloud file sync features and Windows app do a great impression of a Dropbox-style cloud storage service, only running locally within your network, under your control.

This is a solid, business-focused NAS, but it has one weakness that really holds it back. As it’s based on an older Intel architecture and a dual-core Atom processor, it struggles to compete with the faster, Celeron-based NASes, trailing behind them on both backup tasks and sequential file transfer tests. It’s close, but we’d say the Buffalo is the better business NAS, while Asus and Synology win when it comes to the home. 

Western Digital My Cloud Business DL4100 (4TB) specifications

Model number


Price (inc VAT)

£467 (£560)


2yr RTB (driveless), 3yr RTB (populated)

Dimensions (WDH)

170 x 232 x 192mm

Noise level

Not stated


Intel Atom C2338

CPU cores

Dual core

CPU speed, cores


RAM/maximum RAM


Bays (free)

4 (2)

Drive type

3.5in SATA 6Gb/sec hard disk

Max internal capacity


RAID modes

JBOD, 0, 1, 5, 6, 10

Bay type

Slide-in caddy

Hot swap?


2.5in drives supported


SSD support


Status display

5 x status LEDs, 2-line backlit LCD

Gigabit Ethernet ports


10GB Ethernet ports


USB ports (rear)

USB 3, USB 2

USB ports (front)



Additional PSU socket

802.3ad link aggregation


Load balancing


Network failover


Major network protocols


iSCSI target


USB expansion options


NAS OS/firmware

Not stated

Main desktop software

WD SmartWare Pro, WD Sync, MyCloud mobile apps

Remote access


Cloud integration

Dropbox, Elephant Drive


Acronis TrueImage


Plex, Squeeze Centre, IceCast



Testing and Development


Other major services

Joomla, Transmission, WordPress, aMule

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