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DailyTech chats with JMicron about its controllers used in the majority of today's mainstream SSDs

AnandTech’s Anand Lal Shimpi investigated the performance of Intel's X25-M MLC (Multi Level Cell) SSD, and compared it to OCZ Technology's first generation Core SSD, which used Samsung NAND flash along with a JMicron controller. He found that random write performance was abysmal, due to extremely high write latencies.  This was a problem attributed to the JMicron controller, which was problematic since many other SSD manufacturers used JMicron's controller as well.

JMicron has not been too happy about the negative buzz surrounding its controller around the internet. They have been working on the problem but it is hard to change perceptions once first impressions have been made. In the following interview we asked a few questions and gave JMicron the opportunity to tell their side of the story.

Tell us a little bit about JMicron.

JMicron was founded in 2001 and our headquarters are located in Hsinchu Science Park, Taiwan. As a fabless IC design house, JMicron focuses on high speed serial link technology such as Serial ATA, PCI-Express, USB, RAID and Storage applications. Our products are widely adopted by major motherboard and notebook vendors such as ASUS, Gigabyte, ACER, HP, Dell, Toshiba, Lenovo, etc. JMicron is also the first fabless company in Taiwan that can mass produce SATA II application products.

When did you first find out about the write latency issue?

We have been developing SSD technology since 2006 and launched our first generation SSD controller, JMF601A/602A at the end of 2007. It soon attracted the attention of SSD makers because of the feature set and high performance. We found the write latency issue around March, 2008. The issue only happens under a special condition, when the system data is close to full and the host keeps writing data on it. It takes time to do internal garbage collection, data merge and housekeeping.

What did you do to solve it?

We revised the hardware architecture and launched JMF601B/602B in June 2008.  JMF601A/602A was the old version after B version was available. Currently, all JMicron customers are using latest version, including ASUS NB/EeePC, OCZ, Super Talent, Transcend, etc. The B version improves the write latency a lot. Besides, JMicron also can reserve more spare blocks to alleviate the issue. Because more spare blocks reservation would decrease the drive capacity, most SSD makers tend to not enlarge the spare size.

Note by author: This is part of the reason why OCZ Technology's drives are labeled as 30, 60, 120, and 250 GB instead of the regular 32, 64, 128, 256 GB. Almost all SSDs make use of spare blocks; it is not a feature specific to JMicron.

It should also be noted that AnandTech's testing used OCZ's Core V1 , the Core V2 was meant to address deficiencies and integrate some improvements.

OCZ created a new design that uses up to 64MB of cache to eliminate the write latency issue in their Vertex series of SSDs.

What is the current status of JMicron's controllers?

The JMF601/602 is designed for netbooks and portable applications. They are not so good for servers and  heavy access loading (for example, multi-task access at the same time). We think that's why most users have good performance but some don't. We strove to solve the write latency issue after the AnandTech article was published. And we made some progress in the new firmware versions.

Note by author: Each SSD vendor has the ability to use JMicron's own firmware, or to use their own version. The firmware used can make a big difference. More on this in a future article.

What do you have planned for the future?

Some customers have introduced high speed SSDs with JMicron's RAID controller JMB390, plus two JMF602B controllers. The target performance is 233MB/sec on sequential read and 166MB/sec on sequential write. Moving forward, JMicron is developing SSD controllers with DRAM cache and it is expected to be available in Q3 2009. That will totally solve the random read/write performance issue.

DailyTech will present highlights from JMicron's roadmap in a future article.

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So the real question is...
By djc208 on 1/22/2009 7:38:23 AM , Rating: 5
When will Anand pick up one of the Rev B SSDs and verify these claims?

RE: So the real question is...
By therealnickdanger on 1/22/2009 8:00:23 AM , Rating: 5

Yeah, I'm inclined to give JM the benefit of the doubt - no company expecting to survive willingly makes poor-performing products. Unfortunately, the market is flooded with SSDs right now with so many internal configuations that it makes it hard to trust anything but the Intel X25-M.

Without a full, mega-review of just about every model out there by AT, I'm hesitant to spend my money on anything else.

RE: So the real question is...
By Gideonic on 1/22/2009 8:20:35 AM , Rating: 5
an interesting review can be found here:

Concerning the following part of the interview more precisely:

Some customers have introduced high speed SSDs with JMicron's RAID controller JMB390, plus two JMF602B controllers. The target performance is 233MB/sec on sequential read and 166MB/sec on sequential write.

The RAID controller really seems to works , reducing the latency and adding write-speed. The drive seems pretty close to X25-M, costs about the same and has 3x more storage space.

I'd really like to see Anandtech review of that drive.

RE: So the real question is...
By therealnickdanger on 1/22/2009 9:21:17 AM , Rating: 2
Thanks Gideonic. Geez, at this pace, the selection in 6 months will be ridiculous!

If the FM-25S2S-128GBT1 uses the same method as the FM-25S2S-256GBT1 reviewed in your link, I may just grab two for a RAID-0... :D

Here's a review of the 128GB Titan, which appears to be the same controller/method as the 256GB version:

Write speeds are certainly better than the Intel drive, but the lack of on-board cache definitely hurts the G.Skill drives with small read/writes. No stuttering though, which is great!

RE: So the real question is...
By Gideonic on 1/22/2009 10:06:41 AM , Rating: 3
Good find, really seems to be a good deal. Wouldn't hurry buying it though, as according to some rumors ( ) bigger Intel drives are just around the corner with price-drops (hopefully).

Seeing how fast SDDs evolve and that they are still a bit too pricey, it seems to be a smart move to wait for the time being.

By therealnickdanger on 1/22/2009 2:31:42 PM , Rating: 2
Haha, if there's one thing I've never been called, it's "smart". The example I always give are the two 36GB Raptors I bought for ~$500 (combined) several years ago. What I can get for my dollar today absolutely crushes what I got 4 years ago. IMO, it's every bit as smart to buy now. ;-)

RE: So the real question is...
By Jansen on 1/22/2009 8:56:27 AM , Rating: 2
RE: So the real question is...
By mindless1 on 1/22/2009 11:18:26 AM , Rating: 4
On the contrary, they knew the performance parameters of their chips, decided to release them anyway instead of accepting they had overlooked a crucial aspect of performance, and it stung a lot of early adopters.

It would be ridiculous to think they had not found the issues during in-house testing, when even casual use uncovers them. Their sole claim to fame was being earlier to market (by not spending enough time to develop the tech properly) at a good price point.

In other words, screw the customer, so long as we can make a buck. Nevermind the senseless waste on everyone's part we are just too vain to accept we didn't do enough work to have a good product and will let people pay a second time for what they should've had the first time.

That goes for their PATA chips too, this is a recurring theme with JMicron.

RE: So the real question is...
By Kary on 1/22/2009 12:33:25 PM , Rating: 2
of course, and all of the makers of SSD's looked at the JMicron and said "Man, this is the crappiest choice out there, lets go with it."

(end sarcasm)

Even if everyone knew it had a problem, from the number of companies using the design I still have to think it was the best option available at the time.

RE: So the real question is...
By JKflipflop98 on 1/22/2009 12:57:49 PM , Rating: 5
You just said what the poster you replied to said. Except you weren't nearly as eloquent.

Jmicron knew they had the only game in town. They knew it had issues, but since they were the only ones around with a "functional" part, they went ahead and shipped, then collected the cash.

This is a pretty stupid way to do business, because everyone you just screwed over is going to remember that going forward. Jmicron, in my mind, is now a 2nd rate supplier of parts. Ya, they work - but they kind of suck. Just like AMD. Ya, a Phenom works, and it's alright for the money. But what everyone really wants is an i7.

Corporate greed kills another one. Say hello to Creative for us when you get to Hell.

RE: So the real question is...
By leexgx on 1/22/2009 10:19:01 PM , Rating: 2
never really liked jmicro before SSD came any way speed sucked compared to native Sata (more of that was due to been linked to the PCI bus not PCI-e 1x lane)

most of these performance problems are Very apparent when using first gen SSD jmicron, problem should of not taken an year to notices an problem as steep as this one the Write latencys was (V2 fixed) so high any sort of multi writes would kill any benefit of the SSD (some was as bad as 1 second ! delay but most doing 250ms delay) its that slow Vista would not install on some of the SSD drives come up with Delayed write fails on install lol (if you own an intel chip set and have 2 SSD in raid make sure delayed write is turned on useing the intel matrix program should improve performace)

but must admit the hack thay used 2 jmicron chips basically raid to sides of the SSD to remove the problem works very fast as well as lots of storage (250gb) and priced at the same as an intel x35-m (guess on model there) was very price vs storage + speed

RE: So the real question is...
By mindless1 on 1/23/2009 11:27:52 PM , Rating: 2
If you consider AMD 2nd tier, JMicron would have to be 3rd or 4th tier. With AMD you at least get adequate value, the performance you expect that meets the basic need of the part. JMicron could more similarly be equated to Via, netbooks aside since finally something that needs to be cheap, and therefore we don't mind if it's slow and limited, found a niche.

RE: So the real question is...
By ipay on 1/22/2009 8:50:42 PM , Rating: 2
fool me once shame on you, fool me twice shame on me.. u see a pattern??

RE: So the real question is...
By RU482 on 1/22/2009 4:04:25 PM , Rating: 2
yes, please review the OCZ rev2, and Vertex. Hell, review drives with a Samsung controller as well. End user reviews can only be trusted so much

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