Hardware Aspects and Setup Impressions

Western Digital is no stranger to dual-disk RAID-0/-1 capable solutions, having released a USB 2.0 / Firewire 800 capable unit back in 2011 and a first-generation Thunderbolt device in 2012 along with a high-performance variant using VelociRaptor drives later in the same year. All these used software RAID, and that is where things are changing now. The My Book Duo comes with hardware RAID (and hardware encryption, if opted for). It has a USB 3.0 interface. There are two additional USB 3.0 ports in a hub configuration at the rear of the unit.

Hardware & Platform Analysis

The picture below shows the contents of the package. Bundled along with the main chassis is a 36 W power adapter and a USB 3.0 cable. The design of the chassis is very similar to what was used in previous two-bay solutions that supported replacement of disks by users (such as the My Cloud EX2).


The gallery below has some more shots of the chassis as well as some teardown pictures.

In order to provide 'daisy-chaining' capabilities, WD has put in an ASMedia ASM1074 USB 3.0 hub chip on the board. This has one upstream and four downstream ports, and supports UASP (USB Attached SCSI Protocol). We also see a JMicron JMS561 USB 3.0 to dual SATA III bridge chip on the board. In terms of layout, it is obvious that the JMS561 links to one of the downstream ports on the ASM1074. Two other downstream ports are made available on the rear side of the chassis to connect additional USB 3.0 peripherals, as needed by the user.

One of the important aspects of the My Book Duo RAID storage box is the fact that the bundled drives are WD Reds. This allows for a balanced mix of performance and power consumption, while also allowing for the unit to be connected in continuous backup mode to a PC running 24x7.

Software Aspects

Unlike the LaCie 2big Thunderbolt 2, the WD My Book Duo doesn't have any way to configure the RAID level without connecting it to a PC and installing the WD software. At the minimum, the WD Drive Utilities software must be installed, unless the user wants to keep the default shipping RAID configuration (RAID 0). This software allows running of diagnostics (S.M.A.R.T, bad sector detection), RAID management, configuration of idle time for spinning down the disks and full erasure of the disk contents.

The WD Secure software allows setting up of a password to cryptographically protect the data on the disks. Mounting an encrypted drive without the password auto-mounts a UDF filesystem with the password unlocker utility. So, it is possible to move around an encrypted DAS without the need to install the WD Drive Utilities on the PC to which it gets attached.

In addition to these core software utilities, WD also includes a comprehensive backup suite. WD SmartWare Pro can be installed and configured to provide continuous or scheduled file backups. It can also integrate with Dropbox. For system level backup, the WD Edition of Acronis True Image is available. Readers interested in the details of various operational aspects of the WD My Book Duo can refer to the the user manual (PDF).

Introduction Performance Evaluation


View All Comments

  • npz - Monday, July 14, 2014 - link

    If the layout (stride and chunk size) is optimal, it would be close to RAID-0 for multithreaded workloads, since both disks can be read independently. Actually even single threaded/single-process workloads can benefit if the program is using asynch/queued IO.... but this *IF* the DAS unit were using linux (mdadm) or software raid.

    However it's not, it's using a very simple Jmicron controller to do the mirroring.
  • BillT2014 - Monday, July 14, 2014 - link

    I've never before heard that a raid1 component drive might not be universally readable. All the controller is supposed to do is make the two drives identical. A single component of the RAID should be readable by any other system that supports that filesystem. Reply
  • jamyryals - Monday, July 14, 2014 - link

    Would this, or something similar from another manufacturer, work connection to a USB 2.0 port? I would like to use this connected to an older machine, but I don't really want to add a USB 3.0 adapter card. If the device slowed to USB 2.0 speeds that would be fine. Reply
  • celestialgrave - Tuesday, July 15, 2014 - link

    How hot did the drives get? Did the fan ever have to spin up to full speed? How would you characterize the fan noise? Reply
  • BillT2014 - Wednesday, March 25, 2015 - link

    Still waiting for an explanation of this sentence:

    " Inserting the removed disk into a PC's SATA slot didn't show the stored data (as expected, since this is hardware RAID)."

    This defies all sense. RAID is RAID whether it is software or hardware. Maybe the reason the drive wasn't readable is because it was a RAID 0 component? That would never be readable as such under any circumstances. But a RAID 1 drive should always be readable.

  • BillT2014 - Friday, March 27, 2015 - link

    The final sentence also defies everything we know about RAID:

    "Potential areas of improvement, however, include support for hot-swapping drives and provision for data recovery from a RAID 1-member drive directly connected to a PC."

    The reviewer ought to know that if a RAID 1-member drive, directly connected to a PC, is not recoverable, then the problem is the reviewer, not the drive.

    One might wonder if the reviewer was unwittingly testing a RAID 0 member?

    These issues should be addressed and the review should be corrected. It's amazing that it has stood so long like this.
  • yeub - Sunday, March 29, 2020 - link

    thanks for much for the post

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