The JMF667H: JMicron's Long-Awaited SATA 6Gbps Controller

The JMF667H is JMicron's first controller to be used in mainstream client SSDs since the JMF618 in 2010. As one would expect, JMicron is betting a lot on the controller because it's its best and possibly the only chance to get back in the market.

Typical to lower-end controllers, the JMF667H is a 4-channel design. Limiting the channel count allows for smaller die size, which in turn is proportional to the manufacturing cost. Marvell has been doing the same for a while now by offering a 4-channel "Lite" version at a lower cost since especially caching and mSATA SSDs cannot take the full benefit of eight channels anyway.

Furthermore, the JMF667H supports 8-way interleave per channel, which means that up to eight requests can be interleaved in a single channel. Interleaving is the reason why higher capacity SSDs perform better because instead of waiting for each NAND die/plane to respond before issuing a new request, the controller can issue requests to up to eight dies/planes. There is still some overhead compared to having more individual channels because each request takes one clock cycle but interleaving allows for the most efficient utilization of the available channels and NAND. 

The JMF667H supports all the latest SLC and MLC NAND available, including IMFT's 20nm 128Gbit MLC NAND and Toshiba's A19nm NAND. However, the maximum capacity is limited to 256GB, which is a slight drawback. 128GB and 256GB are still definitely the most popular capacities, so in that sense the JMF667H should cover the majority of the market but bigger SSDs are constantly gaining popularity as prices go down. JMicron told me that this is something they'll definitely take into account in future product planning and I would expect the next generation controller from JMicron to support at least 512GB of NAND.

Our first experience with the JMF667H was with the WD Black2 dual-drive earlier this year. Back then I wrote:

"Furthermore, the SSD in the Black2 is only mediocre, although I must say I wasn't expecting much in the first place. There must be a reason why none of the big OEMs have adopted JMicron's controllers and I think performance is one of the top reasons."

JMicron understood our concern. The SSD market is more competitive than ever and mediocre performance is no longer acceptable. JMicron went back to the drawing board and started working on a new firmware with focus on performance consistency, as one of my biggest criticisms was towards the fact that the IOPS would frequently drop to zero in the WD Black2.

After months of development and validation, the firmware is finally ready for the public. It is so new that even the OEMs do not have it available yet and thus JMicron sent us reference design drives. In addition, OEMs tend to make their own customizations and tweaks whereas the reference designs we have are based on the original JMicron firmware.

JMicron sent us four drives in total: two 128GB and two 256GB drives. The difference between the drives are their NAND configurations as one half of the drives use Micron's 20nm 128Gbit MLC NAND while the other half uses Toshiba's A19nm 64Gbit MLC NAND. These are the NAND configurations you would expect to see from the OEMs -- IMFT's 20nm 128Gbit NAND is currently the cheapest option in the market but Toshiba's A19nm 64Gbit NAND provides higher performance. The 256GB model with Toshiba NAND we received is actually over-provisioned down to 240GB for better performance but obviously this is up to the OEM to decide.

JMicron JMF667H Reference Design Specifications
NAND Toshiba A19nm 64Gbit MLC IMFT 20nm 128Gbit MLC
Capacity 128GB 256GB 128GB 256GB
Cache (DDR3-1600) 128MB 256MB 128MB 256MB
Sequential Read 540MB/s 522MB/s 539MB/s 520MB/s
Sequential Write 328MB/s 456MB/s 152MB/s 309MB/s
4KB Random Read 81K IOPS 83K IOPS 65K IOPS 77K IOPS
4KB Random Write 76K IOPS 78K IOPS 37K IOPS 74K IOPS
Power Consumption 2mW / 30mW / 3.4W (DevSLP / Slumber / Maximum)
Encryption No

The table above summarizes the performance differences between IMFT's 128Gbit NAND and Toshiba's 64Gbit NAND pretty well. In best case scenarios the drives with Toshiba NAND provide more than twice the throughput at the same capacity. This is mostly due to the difference in capacity per die because as we have covered before, the capacity per die has a tremendous impact on performance since it's directly related to parallelism. 

NAND Configurations
NAND Toshiba A19nm 64Gbit MLC IMFT 20nm 128Gbit MLC
Capacity 128GB 256GB 128GB 256GB
# of NAND Packages 16 16 8 8
NAND Package Configuration 1x8GB 2x8GB 1x16GB 2x16GB

The JMF667H supports DevSleep and other power saving states (HIPM+DIPM) but it does not provide any form of encryption support. Lack of support for TCG Opal 2.0 and IEEE-1667 is definitely a shortcoming and I would really like to see more manufacturers pay attention to this. Hopefully JMicron's future designs will address this.

One of the biggest issues JMicron had with its first controllers was the lack of cache. When the internal cache was filled up, the drive would start to stutter. Fortunately the later designs brought support for external DRAM, which is the case with JMF667H as well. The controller supports up to 512MB (4Gb) of DDR3, which is plenty of cache for a 256GB drive to store the NAND mapping table and ensure smooth operation. Our 128GB samples use DRAM from Elite Semiconductor Memory Technology Inc while the 256GB samples shipped with Nanya's DRAM, although this is again up to the OEM to decide.

JMicron's biggest advantage is obviously pricing. From what I have heard, the JMF667H is around $4 to $8 cheaper per unit compared to SandForce's offerings. Marvell is a bit cheaper than SandForce and the price delta is about $4 is favor of JMicron, although I must note that Marvell doesn't provide any form of firmware whereas JMicron and SandForce do. That is actually quite a lot given that most 120/128GB SSDs retail for $75 - $90 nowadays and that $4 can be the key to make the drive profitable. Of course, ultimately the pricing depends on the customer and quantity, so the above figures should be taken with a grain of salt, but they still provide some guidance of where the JMF667H stands compared to the competition. 

Introduction Performance Consistency & TRIM Validation
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  • Bindibadgi - Friday, May 30, 2014 - link

    I'm genuinely wondering if the photos are artistically filtered or simply just that bad??
  • hp79 - Friday, May 30, 2014 - link

    I think it's being artistically shot that way. I don't like it either. Photos from AMD article looks fine.

    Nice article though. Good to see another contender in SSD market, back from the hall of shame.

    It's going to be tough though. After sticking a Samsung 840 Pro 256GB in my desktop, and getting a rMBP13 laptop which has proprietary crazy fast SSD, I'm no longer in the market. But if I were to buy another SSD, it'll be whoever is cheapest (after rebates and coupons) with reasonable performance. And it should be a 7mm height so it also fits modern ultra thin laptops, not stupid 9.5mm with no reason.
  • Kristian Vättö - Friday, May 30, 2014 - link

    Better now? I was in a hurry last night as the deadline was approaching way too quickly, so the quality suffered as a result. Bear in mind that we all work from our homes, so the camera equipment and lighting differs greatly from review to review.
  • MrPoletski - Friday, May 30, 2014 - link

    For the love of god, why is it that on every SSD review here, every time I look at the performance consistancy graphs it is always for 4KB random write QD32?

    3 separate tabbed graphs, all saying 4KB random write QD32 - yet clearly only one of them is, the others being perhaps 4kb reads, or 4kb writes QD 1 or 2.

    It's this way every time I read an SSD review on anandtech, has nobody noticed this and fixed it yet or what?
  • MrPoletski - Friday, May 30, 2014 - link

    haha, this time there was an explanation in the article. Ok. IGNORE ME LOL.
  • milli - Friday, May 30, 2014 - link

    'Micron's roadmaps showed that a SATA 6Gbps JMF66x series was planned for the second half of 2010, which made sense given that Intel was integrating SATA 6Gbps to their 6-series chipsets in early 2011. But for some reason, the JMF66x never made it to the market on time.'

    I don't think that's entirely true.
    The Kingston SSDNow V200 used a JMicron JMF661 or JMF662 controller. That product launched towards the end of 2011 with great difficulties. The controller wasn't broken but the firmware was. It took Kingston six months to release a firmware that fixed the problems. Before that firmware the drive was utterly unusable (paused up to 5 seconds sometimes). After the firmware update it became usable and speed was then as advertised.
    You can read about it here:

    This was very weird because the JMF618 found in some Kingston drives, worked very well (as found in Anand's reviews).

    As for the JMF667H, I've used two Transcend SSD340 256GB drives. I suppose they are using the old firmware but performance is okay. Using those systems feels more or less like a system with a M500. Nothing earth shattering.
  • go4aBetterPC - Friday, May 30, 2014 - link

    While nice, I think JMicron is late to the market by about 1 to 2 years. For example the Micron M500 is already on the market. I would just use a another controller such as Marvell. Competitors are announcing and eventually releasing PCIe controllers. Intel has been slow to invigorate the PC market. Perhaps they are too distracted by all their Broadwell yield delays. And some key providers like Micron are trying to make their own controllers or already do in the case of Samsung, but already have relatively low cost SSD drives on the market. Perhaps JMicron should look for a buyer. The SSD market is highly competitive and there are lots of players and interest. I am hoping laptop manufacturers get their act together and start offering more ssd drives as a option. I have decided to not buy many laptops since they don't offer a 128gb or 256gb ssd drive. To me, this is the main way to invigorate the market. Too many companies wait for new Intel processors rather than take control of their own destiny. A $500 laptop that now costs $650 with a ssd would get good reviews and probably would gather a lot of sales.
  • Shiitaki - Wednesday, June 4, 2014 - link

    I just recently picked up a Samsung Evo for school for virtualizing a cluster of computers. I ended up going with the Samsung for 3 reasons. One, consistently high performance, it's the 1TB version. Two, single manufacturer of the whole item, they don't source parts from 'whomever is cheaper'. I'm thinking of Kingston here. There are plenty of reviews of the drive, Samsung is proud of it, so plenty of reviews available.

    I looked at the Optima, a pair of them in fact. But I could only find one review, and I also didn't want to buy something where the review sample is superior to what they are selling to the consumer. While it was cheaper, I didn't have faith that PNY wouldn't do what Kingston has been caught doing.

    The importance of your website to the consumer is huge. I'd like to express my appreciation for's constant diligence. If I can't find a review on something with measurements, I won't buy it.

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