The SSD Anthology: Understanding SSDs and New Drives from OCZ
by Anand Lal Shimpi on March 18, 2009 12:00 AM EST- Posted in
- Storage
The Return of the JMicron based SSD
With the SSD slowdown addressed it’s time to start talking about new products. And I’ll start by addressing the infamous JMicron JMF602 based SSDs.
For starters, a second revision of the JMF602 controller came out last year - the JMF602B. This controller had twice the cache of the original JMF602A and thus didn’t pause/stutter as often.
The JMicron JMF602B is the controller found in G.Skill’s line of SSDs as well as OCZ’s Core V2, the OCZ Solid and the entire table below of SSDs:
| JMicron JMF602B Based SSDs |
| G.Skill FM-25S2 |
| G.Skill Titan |
| OCZ Apex |
| OCZ Core V2 |
| OCZ Solid |
| Patriot Warp |
| SuperTalent MasterDrive |
All I need to do is point to our trusty iometer test to tell you that the issues that plagued the original JMicron drives I complained about apply here as well:
| Iometer 4KB Random Writes, IOqueue=3, 8GB sector space | IOs per second | MB/s | Average Latency | Maximum Latency |
| JMF602B MLC Drive | 5.61 | 0.02 MB/s | 532.2 ms | 2042 ms |
On average it takes nearly half a second to complete a random 4KB write request to one of these drives. No thanks.
The single-chip JMF602B based drives are now being sold as value solutions. While you can make the argument that the pausing and stuttering is acceptable for a very light workload in a single-tasking environment, simply try doing anything while installing an application or have anti-virus software running in the background and you won’t be pleased by these drives. Save your money, get a better drive.
The next step up from the JMF602B based drives are drives based on two JMF602B controllers. Confused? Allow me to explain. The problem is that JMicron’s next SSD controller design won’t be ready anytime in the near future, and shipping mediocre product is a better option than shipping no product, so some vendors chose to take two JMF602B controllers and put them in RAID, using another JMicron controller.
Two JMF602B controllers and a JMicron RAID controller
The problem, my dear friends, is that the worst case scenario latency penalty - at best, gets cut in half using this approach. You’ll remember that the JMF602 based drives could, under normal load, have a write-latency of nearly 0.5 - 2 seconds. Put two controllers together and you’ll get a worst-case scenario write latency of about one second under load or half a second with only a single app running. To test the theory I ran the now infamous 4K random write iometer script on these “new” drives:
| Iometer 4KB Random Writes, IOqueue=3, 8GB sector space | IOs per second | MB/s | Average Latency | Maximum Latency |
| JMF602B MLC Drive | 5.61 | 0.02 MB/s | 532.2 ms | 2042 ms |
| Dual JMF602B MLC Controller Drive | 8.18 | 0.03 MB/s | 366.1 ms | 1168.2 ms |
To some irate SSD vendors, these may just be numbers, but let’s put a little bit of thought into what we’re seeing here shall we? These iometer results are saying that occasionally when you go to write a 4KB file (for example, loading a website, sending an IM and having the conversation logged or even just saving changes to a word doc) the drive will take over a second to respond.
I don’t care what sort of drive you’re using, 2.5”, 3.5”, 5400RPM or 7200RPM, if you hit a 1 second pause you notice it and such performance degradation is not acceptable. Now these tests are more multitasking oriented, but if you run a single IO on the drive you'll find that the maximum latency is still half a second.
The average column tells an even more bothersome story. Not only is the worst case scenario a 1168 ms write, on average you’re looking at over a quarter of a second just to write 4KB.
The G.Skill Titan has recently garnered positive reviews for being a fast, affordable, SSD. Many argued that it was even on the level of the Intel X25-M. I’m sorry to say it folks, that’s just plain wrong.
One of the most popular dual JMF602B drives
If you focus exclusively on peak transfer rates then these drives work just fine. You’ll find that, unless you’re running a Blu-ray rip server, you don’t spend most of your time copying multi-GB files to and from the drive. Instead, on a normal desktop, the majority of your disk accesses will be small file reads and writes and these drives can’t cut it there.
Some vendors have put out optimization guides designed to minimize stuttering with these JMF602B based drives. The guides generally do whatever they can to limit the number and frequency of small file writes to your drive (e.g. disabling search indexing, storing your temporary internet files on a RAM drive). While it’s true that doing such things will reduce stuttering on these drives, the optimizations don’t solve the problem - they merely shift the cause of it. The moment an application other than Vista or your web browser goes to write to your SSD you’ll have to pay the small file write penalty once more. Don’t settle.
But what option is there? Is Intel’s X25-M the only drive on the market worth recommending? What if you can’t afford spending $390 for 80GB. Is there no cheaper option?
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ryedizzel - Thursday, March 19, 2009 - link
Anand,I just wanted to thank you for an amazing article. I am a very picky buyer and technology critic, so I always come to your site for the ‘real’ story on things. In fact for the amount of time, research, and (useful) testing methodologies you invest, I almost feel guilty receiving this information for free. Especially since your findings benefit the industry as a whole since it causes manufacturer’s to fix/improve their products (well at least the smart ones do). The i7 motherboard roundup was another great example of this. Seriously, if you have a place for donations I would send you $50 in a heartbeat. I know it’s not much but if others did the same it would add up to a decent token of appreciation.
Oh and please don’t take people’s grammar or nitpicky corrections the wrong way. Yes it can be annoying, but in the end it does help the article become closer to perfect since others catch little things overlooked by human error. In the end we are all grateful for these articles, otherwise we wouldn’t be here reading them!
bsoft16384 - Thursday, March 19, 2009 - link
You know, the JMicron SSDs really aren't so bad. Yes, you'd have to be crazy to spend $400 on one when there are better options like the X25-M (or the new Vertex series for that matter).But I paid $65 for my 30GiB OCZ "Core" SSD. Yeah, random writes are piss slow. I knew this. The drive replaced the 5400.5 that came with my EEE PC.
I'm not going to be doing any 'extensive multitasking' on my EEE. I'm not running a file server, I certainly don't have antivirus in the background, and I don't spend all day installing new apps.
I'm running 7. Compared with the 5400.5, the system boots faster, Chrome loads faster, but Windows updates take longer. That's a trade-off I'm willing to deal with, considering that I get less noise and more battery life in return.
I can tell you this - the JMicron SSDs beat the pants off of the PCIe MLC SSDs that ship with many netbooks.
So, yeah, I guess this is a product that's "unfit for market". But it's perfect for some of us. If I wanted a boot drive for a Linux media/backup server (along with HDDs for storage), I could see choosing a $50 SSD over a $50 HDD.
It's all about your needs. No one is pretending that JMicron SSDs are fast, at least not at writing. But if your usage is mostly read-centric (or "nothing-centric", as is frequently the case on netbooks), and your chief criteria are low power and low price, the JMicron SSDs do quite well.
petersterncan - Thursday, March 19, 2009 - link
Anand,That was an awesome article... and good for you to give OCZ to do the right thing... and they did!
Kudos also to OCZ for actually listening to feedback and doing something about it.
Adul - Thursday, March 19, 2009 - link
Good work Anand :)SSDMaster - Thursday, March 19, 2009 - link
The stuttering problem with SSD's can be fixed with diskpart. Go do some research before you post an article this massive and convoluted.goinginstyle - Thursday, March 19, 2009 - link
No it does not, it will help if the partition is properly aligned but it is not a cure, neither is the rest of the voodoo magic being spouted on the OCZ forums. They help, but do not cure the stuttering problem with the JMicron based drives. I just love the fact that OCZ wants to sell you a drive (Core series) that does not work properly, have you purchase third party software, and then hack the OS in order to improve the performance of the product. Glad to see it fixed with the Vertex and Summit drives though, but it will take a long time before I even think about using an OCZ product again. I was hoping to see the new ADATA and SuperTalent drives in this article, maybe those are coming in the next segment he mentioned.SSDMaster - Friday, March 20, 2009 - link
Yes, it does.I have a Core series 60GB OCZ drive. I bought it right before Newegg increased the price on the drives. The stuttering was horrible, and worthless even as a secondary drive if it was formatted with XP. Also, after using Diskpart and aligning the drive I could not install XP on the drive and have it bootable.. Which sucked.
But there's ways around that, and guess what, I have a stutter free flash drive for cheap that gets very good performance numbers, and boots Server 2008 in under 10 seconds.
bsoft16384 - Thursday, March 19, 2009 - link
OCZ's product works fine. You may not like the performance, but it's certainly not unusable.The $65 I paid for my 30GiB OCZ "Solid" SSD is about what you'd pay for a USB flash drive. The disk I have has a USB interface, which is very convenient, plus it's plenty fast enough for my EEE PC.
I'm glad that Anand has done these reviews. People need to understand what they're getting into when they by a JMicron SSD. If you don't expect much, you won't be disappointed.
Arguably for a normal notebook/desktop you should buy a normal hard drive if your budget is under $100. But the JMicron SSDs do a good job in netbooks (which, again, aren't too fast to begin with) at a very low price.
I have aligned my partitions and disabled swap on my Windows 7 install (on my EEE). I also have 2GB of memory in my EEE. I haven't done any fancy tweaking on the OS.
Compared with the EEE 900A that I had briefly (PCIe SSD), my EEE 900HA is dramatically faster. You can't run XP or Vista on PCIe SSDs unless you have a lot of patience. You *can* run it on a JMicron SSD.
I honestly don't notice any stuttering. I don't run antivirus and I don't multitask much on this machine. If I demanded from my EEE what I demand from my desktop (Q9300 + 8GB + WD6400AAKS), I know that the SSD would choke up. But I'm not going to do that on a 1.6GHz single-core Atom anyway.
So, yeah, OK. I guess I think that trashing JMicron SSDs is a little like trashing USB flash drives for being slow. Paying $300 for a UFD would be stupid, as is paying $300 for a JMicron SSD. But in the sub-$100 category, you don't expect much.
When better SSDs drop below $100, maybe I'll upgrade. Until then, I'm enjoying 5 hours of battery life on my 900HA.
tomoyo - Thursday, March 19, 2009 - link
Well I think it's unusable for my needs if I'm running it as an operating system drive. I place a giant important on the latency of the drive at that point and it certainly includes random writes. Which is why I would never ever buy an ssd that's majorly below the Intel write performance. It's not worth the price premium or loss of storage size compared to the standard hard drive.Bikerskummm - Thursday, March 19, 2009 - link
Fantastic article Anand!Just a few thoughts:
I have had some trouble replicating some of the Samsung SLC results...
Despite filling the drive up and emulating a well used drive as described in the article I cannot get my Sammy drive's performance to degrade as much as you managed to especially regarding random write performance...
Now my system used for testing is a socket 775 (qx9650) and I was testing on ICH9R and WINXP (SP3) but still I would expect to see similar figures ...
I do not have an X58 system to test on at the moment but I would be very interested if The Sammy SLC drives were shown to degrade faster / perform worse with a X58 / ICH10R / Vista x64 (SP1?) setup...