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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coil222 - Wednesday, March 18, 2009 - link
Yes I run a pair of MTRON 7500s in a raid 0 stripe for my OS and Gaming (wow). I don't recall numbers off the top of my head but tests were better on the raid 0 than a single drive configuration.Watch this:
http://www.youtube.com/watch?v=96dWOEa4Djs&fea...">http://www.youtube.com/watch?v=96dWOEa4Djs&fea...
sawyeriii - Wednesday, March 18, 2009 - link
I just wanted to state how much I loved the combination of technical and real world information in this article.What is the possibility of having different page sizes built into a drive? I.e. you could have a drive with many 1k page packages on one die, 2k on another, and most others 4k. Could that theoretically help? Could the controllers work with that (or would you need to combine multiple 1k's into a 4k transfer size)?
PS One note on page 3, the VelociRaptor and Intel in the first chart (responce time) are switched, however the text is correct.
StormyParis - Wednesday, March 18, 2009 - link
the ugly truth is that an SSD won't let you do anything that you couldn't do without it, and due to its cost and small capacity, it's not a replacement drive, it's an extra drive: not less power consumption but more, not less noise but just the same. You just gain a bit of time when booting up and lauching apps... which I do about 1/week and 1/day, respectively. Assuming your system has enough RAM (and if it doesn't, buy RAM before buying an SSD !), you won't feel much difference once the apps are launched.For the same cost, I'd rather buy a bigger screen.
It's urgent to wait for prices to come down. But I'm all for lots of people buying them now and help get the price down for us wiser buyers.
Rasterman - Thursday, March 19, 2009 - link
I've already decided my next system in a few months will have one, after you go through 5 hard drive failures (over several years) lets see how much your willing to pay to not have to put up with it anymore. If you use your PC for anything useful (work) then an SSD is a no brainer even at $1000/64GB IMO if the data security is there, speed is secondary for me.When you already have the best screen, video card, memory, why not have the best drive? And your argument is pretty dumb, almost any upgrade won't let you do anything that you couldn't do without it, not just SSDs.
Calin - Wednesday, March 18, 2009 - link
You get lower power due to the lower power use of the SSD and the fact that the other drive is not stressed with difficult access patterns (small random reads/writes). Remember that idle power of a SSD drive is very low7Enigma - Wednesday, March 18, 2009 - link
No, his comment was accurate for most users. Due to the small capacities and high cost these will be used as boot drives primarily with maybe a single heavily used program (say the current game or program you are playing/using), the rest will be on an additional drive. So while the power consumption of the SSD would be less than the old drive, the aggregate power usage of both (even when the larger storage drive is primarily at idle) will be higher than the single HD.And I believe you meant to say traditional HD for idle power?
strikeback03 - Wednesday, March 18, 2009 - link
If all you were going to throw on the drive is the OS and a game, a 32GB drive should be plenty. The reason the 80GB and up range is important is so general consumers can load all their programs on it.But yes, in consumer usage other than a laptop, some people who were previously using one drive for both boot and storage would likely need a mechanical HDD is addition to the SSD. OTOH, those who were using a Velociraptor (or RAID array) for boot and another drive for storage will see their power consumption decrease.
sawyeriii - Wednesday, March 18, 2009 - link
Have you used a SSD? (If so which)I would state that it is not a luxary product, it is a premium product. The price difference you pay WILL translate to faster performance (if you choose correctly). More RAM only helps upto a point.
Remember performance is based on a system of parts...
CPU
RAM
NORTHBRIDGE
GPU
SOUTHBRIDGE
I/O INTERFACE
HDD/SDD
Microsoft's Windows Experience Index has specific flaws, but the concept is sound... The system can only go a fast as the slowest component in the system (relative to the amount of time used by that component).
Testtest - Wednesday, March 18, 2009 - link
... there's also Supertalent's Ultradrive ME (MLC) and LE (SLC) and Photofast's G-Monster v3At least the Supertalent drives are quite a bit cheaper with the same drive layout/controller than the Vertex drives and only differ in the firmware (which isn't bad either).
It's however possible at least with the Ultradrive ME currently to provoke a kinda timeout error after they've been fully filled once and then still beeing written on. I don't own a Vertex so I can't test that there but if it was a controller issue, it should pop up there sooner or later as well (if you take a look in their suppport forum some error reports seem very similar).
Intels have their 80% bug, Indilinx drives have their issues too it seems - let's hope that firmware can cure it!
Great article btw!
iwod - Thursday, March 19, 2009 - link
Both SuperTalent and OCZ 30 / 32 GB drive cost exactly the same on NewEgg$129