Because performance takes a backseat to features in this unit, I'll cover that aspect of the My Cloud EX4 later. The EX4 offers all of the user-friendly features of the original My Cloud, packed in a metal four-bay enclosure that boasts a number of high-end perks the My Cloud does not.

First and foremost among them is RAID support, specifically RAID 5 if you purchase the device prepopulated with drives (which gives you the maximum capacity possible while keeping your data safe from a single drive failure). In addition to RAID 5, the EX4 supports RAID 0 (maximum performance, but no redundancy), RAID 1 (two disks mirrored), RAID 5+Hot Spare (same as RAID 5, but with a spare drive installed and ready to become operational in the event of a drive failure), and RAID 10 (nested RAID).

Western Digital's My Cloud network-attached storage unit earned a Editor's Choice when I reviewed it in October. I praised it for its performance and its user-friendly features. But 3TB is the maximum capacity that WD can deliver in that product, and since it's a single-bay device it can't provide the reassuring redundancy of RAID. The company's announcement of the My Cloud EX4 today erases those limitations and adds a raft of other features. Speed isn't one of them, however.

The unit we tested came from the factory with four 2TB drives in RAID 5, which means any one of the four drives could fail and you would still be able to recover all your data (2TB is reserved for parity, leaving 6TB of usable storage). Because the drives are hot-swappable, you can yank out the failed drive and replace it with a new one, and the EX4 will automatically rebuild the array without any downtime.

Good for the studio

The balance of the EX4's feature set is very appealing. Personally, you'll appreciate its friendly, dashboard-like user interface, its DLNA server and iTunes support so your team can share their favourite tunes, and perhaps even its built-in torrent downloader. Stick your business head on and you'll value its dual gigabit ethernet ports, with support for both link bonding (so you can pool the bandwidth of two broadband connections) and automatic failover (if one connection fails, the EX4 automatically switches to the other). Dual power connections deliver similar functionality: If one power supply fails, the EX4 can automatically switch to the other (though you must purchase the second one). Active directory support enables you to connect an EX4 to your company's domain, and volume encryption means the box won't boot without a password.

You'll also like the EX4's onboard display and its dual USB 3.0 ports. The former keeps you informed as to what's happening with the box without your needing to fire up a client, and you can use the latter to back up USB storage devices. You can also back up the EX4 to a USB storage device, but a more plausible scenario would be to back it up to another EX4 over your local network, or to the cloud using an Amazon S3 or Elephant Drive account. WD includes ten WD SmartWare Pro licenses for client-PC backups in the purchase price, and the NAS supports Time Capsule for Mac backups.

WD also offers mobile apps for Android and iOS devices, along with a number of third-party apps including the ability to run Wordpress and Joomla CMSs. The company will soon release an SDK (software development kit) to encourage additional third-party development for its My Cloud platform.

One feature that's sorely missing from both the My Cloud and the My Cloud EX4 is the ability to sync folders via the cloud. Connected Data's Transporter 2 and QNAP's TurboNAS storage devices, among others, allow you to set up folders on the NAS and on client machines that automatically synchronize over the Internet. When you change a file on one computer, tablet, or smartphone, the updated file automatically goes to all your other linked devices. WD really needs this feature for its products.


The My Cloud EX4 delivers a great collection of features for its price tag. You can buy a bare unit and supply your own drives (WD recommends its own, of course, but the company has also certified a number of its competitors' drives), or you can buy an EX4 that's prepopulated with WD's own Red drives (which are designed for 24/7 operation).

In our benchmarks, the four-drive My Cloud EX4 read both our 10GB collection of files and folders and our single 10GB file somewhat faster than the single-drive My Cloud, but it was significantly slower reading than the much more expensive QNAP TS-469 Pro. (The QNAP box is one of the fastest we've tested, but its £700 street price without drives is almost the same as the EX4's with drives.) As you can see in the benchmark chart, the EX4 was significantly slower than both devices when writing a single 10GB file, and it also fell behind the other two boxes when writing our 10GB collection of files and folders. The QNAP drive was more than twice as fast as both WD drives on the files-and-folders write test.

The smaller My Cloud is equipped with a dual-core CPU, in contrast to the single-core CPU in the EX4. But the EX4's single-core CPU runs at 2GHz, versus the My Cloud's 650MHz processor. The QNAP, meanwhile, offers the best of both worlds: a dual-core processor that runs at 2GHz.

We replaced the EX4's WD Red drives, which spin their platters at 5,400rpm, with four 1TB, 7,200rpm Seagate Constellation drives to see if the faster drives would improve the EX4's performance. It didn't matter: The benchmark results were nearly the same.

For many creative studios, the EX4's low price tag, ease of use and strong feature set trump its slow performance.


The My Cloud EX4 has all the features you want in a four-bay NAS and is priced right, provided that you accept its performance deficiencies.