The OCZ Vertex 3 Review (120GB)
by Anand Lal Shimpi on April 6, 2011 6:32 PM ESTThe Real Issue
While I was covering MWC a real issue with OCZ's SSDs erupted back home: OCZ aggressively moved to high density 25nm IMFT NAND and as a result was shipping product under the Vertex 2 name that was significantly slower than it used to be. Storage Review did a great job jumping on the issue right away.
Let's look at what caused the issue first.
When IMFT announced the move to 25nm it mentioned a doubling in NAND capacity per die. At 25nm you could now fit 64Gbit of MLC NAND (8GB) on a single die, twice what you could get at 34nm. With twice the density in the same die area, costs could come down considerably.
An IMFT 25nm 64Gbit (8GB) MLC NAND die
Remember NAND manufacturing is no different than microprocessor manufacturing. Cost savings aren't realized on day one because yields are usually higher on the older process. Newer wafers are usually more expensive as well. So although you get ~2x density improvement going to 25nm, your yields are lower and wafers are more expensive than they were at 34nm. Even Intel was only able to get a maximum of $110 decrease in price when going from the X25-M G2 to the SSD 320.
OCZ was eager to shift to 25nm. Last year SandForce was the first company to demonstrate 25nm Intel NAND on an SSD at IDF, clearly the controller support was there. As soon as it had the opportunity to, OCZ began migrating the Vertex 2 to 25nm NAND.
SSDs are a lot like GPUs, they are very wide, parallel beasts. While a GPU has a huge array of parallel cores, SSDs are made up of arrays of NAND die working in parallel. Most controllers have 8 channels they can use to talk to NAND devices in parallel, but each channel can often have multiple NAND die active at once.
A Corsair Force F120 using 34nm IMFT NAND
Double the NAND density per die and you can guess what happened next - performance went down considerably at certain capacity points. The most impacted were the smaller capacity drives, e.g. the 60GB Vertex 2. Remember the SF-1200 is only an 8-channel controller so it only needs eight devices to technically be fully populated. However within a single NAND device, multiple die can be active concurrently and in the first 25nm 60GB Vertex 2s there was only one die per NAND package. The end result was significantly reduced performance in some cases, however OCZ failed to change the speed ratings on the drives themselves.
The matter is complicated by the way SandForce's NAND redundancy works. The SF-1000 series controllers have a feature called RAISE that allows your drive to keep working even if a single NAND die fails. The controller accomplishes this redundancy by writing parity data across all NAND devices in the SSD. Should one die fail, the lost data is reconstructed from the remaining data + parity and mapped to a new location in NAND. As a result, total drive capacity is reduced by the size of a single NAND die. With twice the density per NAND die in these early 25nm drives, usable capacity was also reduced when OCZ made the switch with Vertex 2.
The end result was that you could buy a 60GB Vertex 2 with lower performance and less available space without even knowing it.
A 120GB Vertex 2 using 25nm Micron NAND
After a dose of public retribution OCZ agreed to allow end users to swap 25nm Vertex 2s for 34nm drives, they would simply have to pay the difference in cost. OCZ realized that was yet another mistake and eventually allowed the swap for free (thankfully no one was ever charged), which is what should have been done from the start. OCZ went one step further and stopped using 64Gbit NAND in the 60GB Vertex 2, although drives still exist in the channel since no recall was issued.
OCZ ultimately took care of those users who were left with a drive that was slower (and had less capacity) than they thought they were getting. But the problem was far from over.
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SolidSteel144 - Wednesday, April 6, 2011 - link
Why weren't other controllers tested?AMD's SB850 should also be able to handle these drives at full speed.
A5 - Wednesday, April 6, 2011 - link
If you go back and look at the Sandy Bridge launch article (http://www.anandtech.com/show/4083/the-sandy-bridg... you'll see that the Intel and AMD controllers have essentially identical performance. No reason to double his benchmark time for a 1% difference.acripps - Wednesday, April 6, 2011 - link
Newegg should have one to my door tomorrow......The last drop of my yule spending authorization. It will spend the next few years drifting through various machine incarnations....till it passes out of the pool in a give-away pc....somewhere around 2014.watzupken - Wednesday, April 6, 2011 - link
Following this issue I had with them, there won't be another OCZ product from me. Anand did point out a good thing that this issue is far from over since OCZ left buyers like myself and others out in the cold in the exchange. So other than the 60 and 120GB drives, no other drives are eligible for an exchange. Worst case, I got the affected drive back due to an exchange as the earlier drive failed. I return fast drive, get a slow drive back. How nice.devlabz - Wednesday, April 6, 2011 - link
Last few articles I ended up wondering why random read speed in SF controllers is slower than random write. I may have missed some important article explaining all that stuff, tho i read all of them. Isn't flash technology favoring the read speeds? Or it have something to do with lookups for the random data chunks?Most likely this will be the year where I'll try to get a SSD drive, and since my main reason will be to reduce the compilation times of my projects and I think that my biggest gain will be with highest random read IOPs drive? Am I wrong here? Or will it matter that much actually?
FunBunny2 - Wednesday, April 6, 2011 - link
I've read, don't remember where, that the IMFT 25nm NAND has on-die ECC circuitry. So:- did you find such
- is OCZ, or anyone, exercising it
???
Movieman420 - Wednesday, April 6, 2011 - link
Yeah...Tosh also just introduced their 'built-in ECC' nand.http://www.techpowerup.com/143619/Toshiba-Debuts-S...
The thing is, from what I understand anyway, that this nand will take the ECC burden off the controller. Thing is tho that SandForce controllers actually accell at ECC duties vs other controllers. This is a major selling point because as the die process continues to shrink, the ECC burden will continue to increase. So I guess I'm saying that I'm not too sure that more expensive ecc-nand would be practical if the controller doesn't suffer from the increasing ECC issue. Someone with more knowledge about how the SF controller works could probably answer the question best...cough*Anand*cough. ;)
Movieman420 - Wednesday, April 6, 2011 - link
The dismal performance of the Hynix nand was news to me. It does however explain why there were many users with horrid performance posting on the Ocz forums. I suspect these were the ones who where told that the problem was with their PC/Lappy. It has never once been mentioned on the forum that some drives may have low performing nand inside. No wonder they kept reminding folks not to open their drives 'due to potential warranty issues'. It seems Ocz was being less than forthcoming even before the whole 25nm nand thing blew up. I really really REALLY hope that Ocz puts an end to the shady business we've seem for the last few months...they are a great company with a great product. Omission and/or deception isn't gonna fly, especially when you cater to enthusiasts who are not exactly stupid. It's those same 'enthusiasts' who made Ocz's early success possible in the first place. I know that things have since changed and now the vast majority of their sales are to commercial and enterprise customers. They'd never think of pulling this with those customers, but they'll do it to the very people who made their early success possible in the first place? This post and my previous one come from the prospective of a die hard customer who also happens to be an Ocz shareholder as well. Just wish I could afford enough to actually have a say so in the way things go down. :Pxboxist - Wednesday, April 6, 2011 - link
Anand,I'm a very casual hardware enthusiast, and admittedly most of the technical aspects discussed in this article eludes me.
With that said, I don't need to understand everything to continue to be impressed by your enthusiasm for the products in your industry, and the way you carry yourself as an ambassador for all of your users. The way you went after OCZ here has to be applauded.
fixxxer0 - Wednesday, April 6, 2011 - link
after being disappointed in some way with just about every (large) company i've dealt with, whether it be insurance, auto makers, electronics, appliances, you name it... i am glad to see one finally accepting responsibility, and doing the right thing.i do not expect 100% perfection from every company at all times. i know sometime things are DOA, or defective, or flawed. but to actually have a company take that extra step and make it right without you having to sue them is commendable.
personally, when it comes time on deciding which drive to go with, it will mainly be on the numbers, but OCZ's ethics will definitely give them the edge if there is a toss up.