Performance, Conclusion, and Final Thoughts


To avoid any network overhead, we configured the EX4 on a direct gigabit connection to an isolated PC. There is too much variability with a live network, so this is the best way to get consistent results with no outside interference from various network services, etc. We copied the 32 and 64 bit Windows 8.1 installation images to and from the EX4. The larger files gave added time for stable speed readings.



Slightly higher speeds are possible with jumbo frames in use, but these are the out of the box settings. We feel the results are fair given that all links in the chain (switches, routers, network adapters) must support larger than standard frame sizes in order to take advantage of higher MTU settings. The speeds seen above are lower than I would have hoped to see, and were duplicated on two independent test network setups. The some additional testing we performed (below) may shed some more light on a possible cause.


The EX4 also supports the creation of iSCSI volumes. These volumes are stored as image files within the main volume and can be mounted as standard mount points via the built-in iSCSI Initiator in Windows. It took nothing more than pointing the Initiator at the EX4 and formatting within Disk Management. This is an advanced feature implemented in a simple fashion by Western Digital.

We experienced some issues with iSCSI transfers on our sample. Speeds were lower than expected – in the 40 MB/sec range for both reads and writes. This is abnormal for iSCSI links, which normally run closer to the raw gigabit speed of 90-100 MB/sec. These speeds were duplicated on a completely different test system and configuration. Upon firther investigation, it appeared something was causing the EX4 to peg its CPU during these transfers:

We are currently working with WD and will update this space as the investigation continues. With these types of devices, a simple firmware update should correct this issue, and I suspect a future update will fix the issues we are seeing here.



  • Compact, efficient, silent design
  • Highly flexible configuration interface
  • Extremely simple drive replacement
  • Great out of the box / setup experience


  • Throughput speeds were less than stellar

Final Thoughts:

Overall, I am impressed with the Western Digital My Cloud EX4. As a storage product, it offers many storage options at a very reasonable cost, as well as a plethora of way to access that storage. USB devices and other networked targets can all be consolidated through the EX4's excellent interface and then easily accessed in a variety of methods and by a variety of mobile devices. Speeds were noted to be average for a typical consumer NAS device, but the strengths of the EX4 are clearly in the features and app capability.

The pile of features is great, but may be leading to complications as we saw some odd CPU bottlenecks while performing file transfers to and from the device, though we suspect those will be sorted out with future firmware updates. The Easy Slide system makes drive swaps as simple as humanly possible. Redundant power supply and ethernet failover capability are welcome additions, and while those are more expert-level features, it's good to see enterprise goodies trickle down into a consumer product.

The EX4 gets a Silver pending resolution of the odd speed issues we're seeing. Once those are sorted, it stands a good chance of being upgraded to Editor's Choice for a feature packed and cost effective network storage device.

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