The Drive

The Black2 consists of a 120GB SSD and 1TB dual-platter 5400rpm hard drive. It's not a hybrid drive (or SSHD) by definition like the Momentus XT because there's no caching involved. The SSD and hard drive appear as separate partitions, giving the end-user the power to decide what data goes to the SSD and what doesn't. WD calls the Black2 a dual-drive, which is a logical name for the drive because it's fundamentally two drives in one.

(Sorry for the poor quality photos -- I no longer have access to the DSLR I used before)

WD Black2 Specifications
Interface SATA 6Gbps
Sequential Read 350MB/s
Sequential Write 140MB/s
Power Consumption 0.9W (idle/standby) / 1.9W (read/write)
Noise 20dBA (idle) / 21dBA (seek)
Warranty 5 years
Price $299

Included in the retail package is a USB 3.0 to SATA adapter and Acronis True Image WD Edition (via download) for easy data migration. There is no driver disc to my surprise but a small USB drive, which when plugged in runs a command that sends you to WD's download page (i.e. the actual drivers have to be downloaded).

Internally the drive is rather unique. The hard drive itself is the same as WD's Blue Slim model (7mm dual-platter 5400rpm drive) but in addition to the hard drive, there are two PCBs. The bigger PCB contains the SSD components (controller, NAND, DRAM) and the smaller one is home to Marvell's bridge chip, which allows the SSD and hard drive to utilize the same partition table.

WD went with a rather rare JMicron JMF667H controller in the Black2. It's a 4-channel controller and is based on the ARM9 instruction set, but as usual JMicron doesn't provide much in the way of public details.

JMicron used to be a fairly big player in the consumer SSD space back in ~2009 but the lack of a SATA 6Gbps controller pushed SSD OEMs to go with other manufacturers. The JMF667H isn't JMicron's first SATA 6Gbps controller, although it seems that all the members of JMF66x family are mostly the same with a few tweaks. I've seen the JMF66x controllers used in some Asian brand SSDs (e.g. Transcend SSD740) but the biggest demand for JMF66x has been in the industrial SSD side.

As for the NAND, WD has only disclosed that the NAND is 20nm MLC, suggesting that we're dealing with IMFT NAND (Micron or Intel). I tried googling the part numbers but it appears that the NAND is custom packaged as there was no data to be found. However, I'm guessing we're dealing with 64Gb dies, meaning eight dies (64GB) per package. There's also a 128MB DDR3-1600 chip from Nanya, which acts as a cache for the JMF667H controller.

Setting Up the Black2

When the Black2 is first connected, it appears as a 120GB drive and gaining access to the 1TB hard drive portion requires driver installation. The reason why the driver is required is due to the limits of the SATA protocol. Connecting two drives to a single SATA port would require port multiplication, which isn't supported by all SATA controllers as it's not an official requirement. Most modern SATA controllers do support port multiplication but for instance older Intel and nVidia chipsets don't. It's always better to play it safe and not have any specific hardware requirements, especially as most people have no idea what chipset is in their system.

Once the drivers have been installed, the Black2 will show up as a single drive with two partitions. The way this works is pretty simple. Operating systems use Logical Block Addresses (LBAs) for read/write commands, which are used to keep the data seen in the OS and the data in the drive in sync. As OSes have been designed with hard drives in mind, they use linear addressing, meaning that the LBAs start from 1 (i.e. the outer circle of the hard drive) and increase linearly as more data is written. Partitions are based on LBA ranges and as some of you might remember (and may still do it), splitting a hard drive into two partitions was a way to increase performance because the first partition would get the earliest LBAs with the highest performance.

In the Black2, the earliest LBAs (i.e. 120GB) are assigned for the SSD partition, whereas the rest are for the hard drive. The Marvell chip keeps track of all the LBAs and then sends data to the SSD or hard drive based on the LBA.

Out of interest, I also tried creating a 1120GB volume to see how the drive reacts. It certainly works and I was able to read and write data normally, but the issue is that you lose control of what goes to the SSD and what doesn't. As the earliest LBAs have been assigned to the SSD, the SSD will be filled first and once 120GB has been written the drive moves to writing to the hard drive, meaning that you are pretty much left with the hard drive for anything write related. If you go and delete something that's in the SSD, the next writes will go those SSD LBAs so in theory you could use the Black2 as a single volume drive, but it wouldn't be efficient in any way.

Unofficial Mac Support

The drivers WD provides are Windows only but there is a way, at least in theory, to use the drive in OS X. You need Windows access for this and what you do is set up the partitions in Windows and then use OS X's Disk Utility to format the partitions from NTFS to HFS. 

Unfortunately I don't have a Mac with USB 3.0 port to thoroughly test the Blackin OS X, so this is merely a heads up that it may work. I was able to read and write to the drive normally but without a faster interface I can't test that the writes are indeed going to the SSD when they should be. In theory yes, but it's possible that the drivers include more than just an automated partition set up.

Test System

CPU Intel Core i5-2500K running at 3.3GHz (Turbo and EIST enabled)
Motherboard AsRock Z68 Pro3
Chipset Intel Z68
Chipset Drivers Intel + Intel RST 10.2
Memory G.Skill RipjawsX DDR3-1600 4 x 8GB (9-9-9-24)
Video Card Palit GeForce GTX 770 JetStream 2GB GDDR5 (1150MHz core clock; 3505MHz GDDR5 effective)
Video Drivers NVIDIA GeForce 332.21 WHQL
Desktop Resolution 1920 x 1080
OS Windows 7 x64

Thanks to G.Skill for the RipjawsX 32GB DDR3 DRAM kit

Introduction Performance Consistency & TRIM Validation


View All Comments

  • Shadowmaster625 - Thursday, January 30, 2014 - link

    What a joke. For $300 you can just buy a 512GB SSD and not have to deal with a 2nd partition that might just decide to disappear at any moment due to its odd driver dependency. There's actually one on sale right now for $260. What is WD smoking? Reply
  • LauRoman - Thursday, January 30, 2014 - link

    As i understand it it is not a weird driver dependency. The driver is really only needed to flip a switch that woun't suddenly flip back by itself, even if you destroy the drive's mbr/gpt. It should work in any os after the switch is flipped. I don't know if you need a Windows install to switch it on though. Reply
  • Panzerknacker - Thursday, January 30, 2014 - link

    Exactly, that's what I'm thinking as well, the driver is only used to flip a certain switch that's unique in this particular drive. Now that I'm thinking of it they probably did this to help with installing Windows. When installing Windows the installer will only find the 120gb partition, Windows has the strange behaviour of messing around with partitions during installation and putting system stuff on other partitions. Normally you can disconnect the other drives in the system, not on this one ofc because it's 2 in 1. Then when everything is installed you can enable the other partition with the switch triggered by the driver.

    I'd wonder how you would do this without Windows tho, they should also include a hardware switch.
  • mikato - Friday, January 31, 2014 - link

    I HATE that. Detaching everything but the SSD is standard procedure during Windows installation now because of that. It's a nasty surprise when you decided to take out your hard drive or switch it with another only to find that Windows won't boot now, even when you had installed Windows on the SSD! Do you know if Windows 8 does this? Reply
  • HisDivineOrder - Thursday, January 30, 2014 - link

    It's been a long time since WD truly impressed me with a new product. Reply
  • Guspaz - Thursday, January 30, 2014 - link

    I've seen the 1TB Samsung 840 EVO go under $500. If you gave me the choice between paying $300 for a slow 1TB HDD with a pretty terrible 120GB SSD, or paying $500 for a fast 1TB SSD, which do you think I'd pick?

    About the only thing that could make the WD solution interesting is if it offered a substantially more attractive price than the SSD (and "somewhat cheaper" isn't), and if it had the SSD caching solution in hardware so that it could just be plugged in and used as a normal drive.

    With a full 1TB SSD costing not much more than this thing, it's not useful for the "notebook with only one 2.5" slot" scenario... or any other scenario.
  • coolhund - Sunday, February 9, 2014 - link

    Exactly. Also keep in mind that SSD prices keep falling and falling, while HDDs still havent gotten back to the prices that we had before that 'flood' and are not really getting cheaper nowadays. And thats why it will fail, just like the hybrid ones. I think it will actually fail even more. Reply
  • mobutu - Thursday, January 30, 2014 - link

    Too little, Too late

    I mean with very good 1TB SSDs ready to go mainstream at 400-500USD this wd2 is completely useless, especially for all the people that already use SSDs and know what a tremendous impact it has over a hdd dinosaur (performance/power/heat/silence/formfactor) (msata at 1TB already gimme a break must be a joke to look at wd2).

    HDDs are close to extinct, it is a matter of time/price until they'll dissapear completely exactly like the FDD ... both are/were huge bottleneck to a system.
  • chizow - Thursday, January 30, 2014 - link

    I thought this was pretty useless when it was announced a few months ago, but with the increasing popularity of SFF and NUC-like devices, this drive would be perfect. Reply
  • Gigaplex - Thursday, January 30, 2014 - link

    Or you could just get a 1TB SSD, this drive isn't that much cheaper. Reply

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