Western Digital is well known to the average consumer as a hard drive manufacturer. By extension, it also opens up the network-attached storage (NAS) market to them. In the second half of 2013, the company started to unify their embedded Linux-based offerings under the My Cloud tag. The My Cloud network attached hard disk and the My Cloud Mirror (2-bay offering) targeted home users, while the EX 2-bay and 4-bay units targeted prosumers and small office / home office (SOHO) installations. For business users, the DL series was introduced earlier this year. A few weeks back, Western Digital announced an updated operating system for the My Cloud units - My Cloud OS 3. Along with that, the My Cloud Mirror Gen 2 was also introduced. In this review, we will take a look at the My Cloud Mirror Gen 2 and the features enabled by My Cloud OS 3.

Introduction and Testbed Setup

Western Digital's embedded Linux-based NAS offerings target a wide range of market segments. The My Cloud Mirror Gen 2 targets the typical average consumer - someone who has a vague idea of what network attached storage means, but has never used one in his setup. This type of customer is typically not very tech-savvy, and so, ease of use is very important. Several features that power users take for granted might not be necessary in a product targeting such a consumer. Eagle-eyed consumers might note that the My Cloud Mirror Gen 2 and the My Cloud EX2 share a similar chassis. The difference between the two is in terms of firmware features. The following aspects are not supported in the My Cloud Mirror Gen 2:

  • iSCSI LUNs
  • Encrypted shared folders / volumes
  • IPv6 for the network interface
  • Hot-swap capability for hard drives
  • Active Directory support

Compared to the My Cloud Mirror model from last year, the Gen 2 version has a faster internal platform. While Gen 1 used the Marvell ARMADA 370 SoC with a single-core ARMv7 CPU running at 1.2 GHz, the Gen 2 uses the Marvell ARMADA 385 SoC sporting two ARM Cortex-A9 cores running at 1.33 GHz. Other than that, the other specifications such as the external I/O ports and amount of RAM on the board remain the same. As we shall see later, the faster CPU will definitely be of help in handling the extra features provided by the My Cloud OS 3.

Given the nature of the target market, there is no diskless version of the My Cloud Mirror Gen 2. Western Digital ships three capacity points - 4TB, 6TB and 8TB, priced at $310, $370 and $410 respecitvely. The units ship with two WD Red drives (with NASware 3.0) of equal capacity.

The specifications of our review unit of the WD My Cloud Mirror Gen 2 are provided in the table below

WD My Cloud Mirror Gen 2 Specifications
Processor Marvell ARMADA 385 (MV 88F6821)
(Dual-Core ARM Cortex-A9 @ 1.33 GHz)
RAM 512 MB
Drive Bays 2x 3.5" SATA II / III
Network Links 1x 1 GbE
External I/O Peripherals 2x USB 3.0
Expansion Slots N/A
VGA / Display Out N/A
Full Specifications Link WD My Cloud Mirror Gen 2 Specifications
Price USD 310 (2x 2TB)

The various specifications of the NAS are backed up by the data gleaned via SSH access to the unit. The lspci output refers to the PCIe lanes on the 88F682x [Armada 385] ARM SoC. The actual part number is 88F6821 according to Marvell's specifications list.

The WD My Cloud Mirror Gen 2 ships with a network cable and a 36W (12V @ 3A) power adapter.

The industrial design of the unit is similar to what was used in previous two-bay solutions that supported replacement of disks by users - the WD EX2 and the WD My Book Duo come to mind. Even though hot-swap is not officially supported, we did observe that hot-swapping worked - streaming of content from the NAS was not interrupted when one of the disks was suddenly yanked out. Adding a new disk to the volume was also not an issue as long as the instructions in the web interface were followed. Coming back to the chassis design, the disk removal mechanism is not completely tool-less. After popping open the top of the My Cloud Mirror Gen 2 unit, a metal flap needs to be unscrewed and the disks need to be pulled out with an attached tag (pictures in the gallery below). This requires a little bit of force while tugging. Considering that consumers have been taught to treat hard disks as fragile and not to be subjective to excessive force, this is not a pleasant experience. On the other hand, Western Digital might not be expecting consumers in this target market to replace the drives on their own.

In the rest of the review, we will take a look at how to setup and use the WD My Cloud Mirror Gen 2. We will also be looking in detail into the official WD apps on the mobile (WD My Cloud) and desktop (WD Sync) side. This is followed by benchmark numbers for both single and multi-client scenarios using a CIFS share. Finally, we will also talk about power consumption and RAID rebuild numbers. Prior to all that, we will take a look at our testbed setup and testing methodology.

Testbed Setup and Testing Methodology

The WD My Cloud Mirror Gen 2 can take up to 2 drives. Users can opt for either JBOD, RAID 0 or RAID 1 configurations. WD ships the units by default with the WD Red drives in RAID-1 (mirror). However, to keep things consistent across different NAS units, we benchmarked the unit with two Western Digital WD4000FYYZ RE drives. Our testbed configuration is outlined below.

AnandTech NAS Testbed Configuration
Motherboard Asus Z9PE-D8 WS Dual LGA2011 SSI-EEB
CPU 2 x Intel Xeon E5-2630L
Coolers 2 x Dynatron R17
Memory G.Skill RipjawsZ F3-12800CL10Q2-64GBZL (8x8GB) CAS 10-10-10-30
OS Drive OCZ Technology Vertex 4 128GB
Secondary Drive OCZ Technology Vertex 4 128GB
Tertiary Drive OCZ Z-Drive R4 CM88 (1.6TB PCIe SSD)
Other Drives 12 x OCZ Technology Vertex 4 64GB (Offline in the Host OS)
Network Cards 6 x Intel ESA I-340 Quad-GbE Port Network Adapter
Chassis SilverStoneTek Raven RV03
PSU SilverStoneTek Strider Plus Gold Evolution 850W
OS Windows Server 2008 R2
Network Switch Netgear ProSafe GSM7352S-200

The above testbed can run up to 25 Windows 7 or CentOS VMs simultaneously, each with a dedicated 1 Gbps network interface. This simulates a real-life workload of up to 25 clients for the NAS being evaluated. All the VMs connect to the network switch to which the NAS is also connected. The VMs generate the NAS traffic for performance evaluation. However, keeping in mind the nature of this unit, we restricted ourselves to a maximum of 10 simultaneous clients.

Thank You!

We thank the following companies for helping us out with our NAS testbed:

Setup and Usage Impressions
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  • Goodspike - Saturday, October 10, 2015 - link

    My concern about these consumer devices (and other consumer Cloud backup solutions) is how will the ISPs respond to having several thousand GB of data being constantly uploaded by each customer? On most my machines I try to avoid having my OS files uploaded to a Cloud service, but I wonder how many people do that. Someone could probably set one of these up in a manner where it would be uploading files 24/7.
  • stephenbrooks - Sunday, October 11, 2015 - link

    I imagine these are differential backups, so only modified files get transferred, based on comparison of file lists and modified dates (only a few MB for the whole disk).

    Also ISPs already have a bunch of BitTorrent people who upload constantly and they seem to cope with that (sometimes they get throttled).
  • bobbozzo - Sunday, October 11, 2015 - link

    I don't think this is copying anything to WD's servers, except when you use remote access, then it downloads on-demand to the remote device, possibly via WD's network.
  • Conficio - Saturday, October 10, 2015 - link

    Really no IPv6 support? Is this 1999 or what? It's linux underneath, so one has to deliberately disable IPv6.
  • ganeshts - Saturday, October 10, 2015 - link

    It is all part of a differentiation drive when compared to the EX2 series.

    I suspect most of the consumers who are going to buy this unit probably don't even know what IPv6 is.
  • Sivar - Monday, October 12, 2015 - link

    I've used two older WD EX2100 units (12TB) and have found WD's configuration interface to be the easiest to use of any NAS I have ever worked with. I think my grandma could set one up.
    Their software developers and UI designers deserve a medal.
  • whiteonline - Friday, October 16, 2015 - link

    What SSH client is that?
  • Moishe - Wednesday, November 4, 2015 - link

    Thanks for mentioning the lack of features in this versus the EX2. Lack of encryption in this is a deal killer.
  • mikato - Saturday, November 14, 2015 - link

    I don't think you said anywhere in the article that this 4TB model comes with 2 x 2TB drives! I had to look at the photos to see that. You list "USD 310 (2x 2TB)" for the price entry in the specs table, but that doesn't say anything about which model it is for (I see it's the 4TB one). If set up as a mirror, as by default, and as the product is named, you only get 2TB or storage. They sell this as having capacity of 4TB. WD's website gives you no hint about this. I looked up the listing on Amazon and thank goodness they do have "4 TB 2X2TB" in the technical details, but otherwise there is no hint there either - actually when you choose the model at the top it says "Capacity" next to the 4TB which actually only gives you 2TB capacity.

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