by Josh Shaman

WD My Book Thunderbolt Duo 8TB Review (WDBUSK0080JSL)

The Western Digital My Book Thunderbolt Duo 8TB is an external storage unit that provides top-of-the-line capacity in a book-sized enclosure. Near the end of 2012, we reviewed the WD My Book Essential which provided the highest capacity on the market in a single hard drive at 4TB. Now, we're examining the WD My Book Thunderbolt Duo formatted specifically for Mac and available in 4TB, 6TB, or 8TB. Our test model comes with a whopping 8TB storage capacity. The Duo crams that exceptional storage capacity into a relatively small space using two 3.5" 4TB Hitachi Deskstar 5K4000's.

With individual customization in mind, the WD My Book Thunderbolt Duo is designed for both creative professionals craving performance and capacity and users that require loads of storage for local backup or archive. The Duo is user-configurable and can be set to RAID 0 (striping) for performance, RAID 1 (mirror) for redundancy) or JBOD to use two individual drives selecting between HFS+J or ExFAT on either disk. This latter feature makes the Duo ideal for users looking to run Windows on a Mac, while the two former features provide users the flexibility to focus primarily on having secure storage or performance from their drives.

The WD My Book Thunderbolt Duo is currently available for purchase, has a street price of $790, and comes with a three year limited worldwide warranty.

WD My Book Thunderbolt Duo Specifications

  • Capacity: 4TB, 6TB, or 8TB
  • Interface: 2xThunderbolt
  • Dimensions (H x D x W): 6.5 x 6.2 x 3.9 in. / 165 x 157 x 99 mm
  • Weight: 4.98lbs / 2.26kg
  • Operating Temperature: 41ºF to 95ºF / 5ºC to 35ºC
  • Non-Operating Temperature: -4ºF to 149ºF / -20ºC to 65ºC

Design And Build

The exterior of the WD My Book Thunderbolt is similar to that of the Duo VelociRaptor line and has the book shape that gives the line its name (albeit a very thick book). The Duo is encased a glossy gray plastic enclosure. It also has four rubber feet and a ventilated black plastic top and bottom pieces for passive cooling which allows for sufficient circulation. On the rear of the unit, there are two Thunderbolt ports as well as the DC input and a Kensington lock slot. The Thunderbolt connectivity is a huge plus as it allows for speeds around 2 times faster than USB 3.0 and 12 times faster than firewire--an important figure since this unit comes preformatted for Mac. Couple that with the ability to Daisy Chain the Duo, and there's some serious performance application. However, given the attention paid to performance, WD could have selected 7200RPM HDD's instead of 5400RPM, but the high-performance line is generally left to sister brand HGST's G-Technology line. 

The Duo's design, while not as sleek as it could be with more refinement, still matches the Mac scheme and is functional. Nonetheless, it is still worth noting that while models like the G-Technology 4TB G-DRIVE are built with solid aluminum, the Duo relies on a lower cost plastic enclosure.

On the top of the Duo is a push-button latch holding the lid in place. This provides access to a honeycomb metal ventilation grate removable by twisting a screw with your fingers like a wind-up toy. This feature is extremely convenient giving tool-less access to the drives. Inside sit the two trayless bays firmly holding the 4TB Deskstar 5K4000's. From there, drive removal is simple. There are plastic pull tabs attached one to each Deskstar and with a simple tug the hard drive is extracted. This makes long-term servicing simple, whereas with other devices like the aforementioned G-DRIVE, a number of screws may need to be removed.

Performance and Synthetic Benchmarks

Benchmarking Comparables:

The Western Digital My Book Thunderbolt Duo posts 2MB sequential reads at 248MB/s and writes at 249.1MB/s, placing it far behind both the LaCie 2big which had reads at 327.1MB/s and writes at 273.5MB/s and the WD Velociraptor which had reads at 362.6MB/s and writes at 347.6MB/s. Clearly the drive is hampered by the 5,400RPM drives inside compared to the alternatives. 

In large-block random read and write, the My Book came in at 108.2MB/s and 145.5MB/s respectively. The My Book was in last overall for reads, but it came in second beating the LaCie in writes. The LaCie posted reads at 135.4MB/s and writes at 94.3MB/s. The speedy Velociraptor placed first again with reads at 176.1MB/s and writes at 212.6MB/s though its limited capacity top-end of 2TB doesn't make this comparison quite apples-to-apples. 


The 8TB WD My Book Thunderbolt Duo offers users the ability to have first-class storage capacity with proven HDDs in a reasonably good-looking enclosure. The enclosure isn't the most high-end we've seen, but is quite capable and has a user-friendly design for drive maintenance and upgrades. Another significant value point that no doubt many users will love is that the My Book Duo offers users the ability to switch between JBOD, RAID 0, and RAID 1 modes.   

Not surprisingly, the Duo couldn't perform as well as the Velociraptor and its 10,000 RPM drives. It did come in close competition with the LaCie, performing better in the large-block random writes. While the Duo would perform better with 7,200 RPM drives and could benefit from an aluminum exterior for both design and aided cooling, its exterior design and inner workings allow it to deliver a good value with a gargantuan 8TB capacity, Thunderbolt connectivity, and solid build.


  • Thunderbolt Connectivity
  • 8TB Maximum Storage Capacity
  • Preformatted for Mac
  • Tool-less entry and Drive Servicing


  • Plastic Enclosure
  • 5,400 RPM drives

Bottom Line

The WD My Book Thunderbolt Duo offers great connectivity and tremendous capacity in a design that users will really appreciate. It's price per gigabyte is reasonable for users that need this level of storage.

WD My Book Thunderbolt 8TB at

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