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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jjj - Wednesday, April 6, 2011 - link
any chance of a comparison soon for the new gen SSDs running on p67 vs the non native sata 3 controllers out there(the marvell controller on many 1366 and 1155 boards or/and some cheap PCIe sata3 cards) and maybe an AMD system too?A5 - Wednesday, April 6, 2011 - link
I think they did a comparison in the P67 article. The P67 controller is the fastest, followed by AMD (it's within a few %), and then the 3rd part controllers are a good bit slower.Movieman420 - Wednesday, April 6, 2011 - link
What more can I say? I've been chomping at the bit over this issue ever since SR broke the story. As a loong time Ocz customer (ok...fanboy..lol) I couldn't believe Ocz was behaving like that. The max speed rating using the fastest test available is excusable...like you said, if Ozc would have went the altruistic route then the competition would have take full advantage in about 1 millisecond. After finding out about the inevitable switch to 25nm I quickly ordered another drive for my existing array from a lesser known vendor that I hoped was still selling older stock. I received the drive and to my dismay it was a 25nm/64Gb piece. Adding this drive to my existing array of 34nm/32Gb drives would have a definite negative effect. Which brings me to my point."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."
This is only partially true. Replacements were offered based on drives that formatted below IDEMA capacity. If your drive formatted to the correct size, you were not eligible to swap. The only problem is that the 64Gb dies were also used in Vertex 2/Agility 2 drives that feature 28 percent over-provisioning (i.e. 50, 100, 200gb models). In this case the decreased capacity was 'hidden' for lack of a better term. This is where I locked horns with them. The exchange was only offered for the 60'E' and 120'E' drives even tho many others suffered the same performance issue for the same reason. I had to raise a bit of hell before they agreed to replace my 64nm/64Gb 'non-E' drive with a 34nm replacement. At first they would only swap for another 25nm drive and I stated that my issue was with performance NOT die size. They ended up replacing my drive with a 34nm model only because it would have put a hurting on my existing raid array of 34nm drives...they made it clear that this was an exception since I had a raid array that would be negatively affected. So anyone who bought a 28 percent OP drive with 64Gb nand chips was DENIED any sort of exchange unless a raid array was involved. As far as I know, that policy still stands unless Ryan or Alex decides to make good on the exchange for 28 percent OP, non 'E' 64Gb die drives which are internally identical to the 'E' drives just with a different amount of OP set by the firmware. While I may have been 'lucky' if you will because I had an array involved, there's people out there that purchased a high OP model which if anything should be a slightly better performer and instead it's the complete opposite. Charge a premium for the more expensive NAND? Absolutely! Just don't offer a half hearted exchange that doesn't cover all models affected...and not just for the ones whose OP doesn't hide the issue.
CloudFire - Wednesday, April 6, 2011 - link
thanks anand! really glad you put some pressure on Ocz. I hope other companies will follow suite as well. Here's to hoping you'd continue to do the right thing for us consumers in the future! :DDennis.Huang - Wednesday, April 6, 2011 - link
Thank you for the review and for your actions on behalf of customers. This was a great review for me as a new person to SSDs. Do you have any thoughts of the performance of the 480GB version of the Vertex 3 and/or do you plan to do a review on that version too?kensiko - Thursday, April 7, 2011 - link
I saw some number on the OCZ forum, I think it came from Ryder, for the 480GB and it performs even better than the 240.kensiko - Thursday, April 7, 2011 - link
Here:IO METER (QD=1) 2008 on P67 SATAIII
120GB 240GB 480GB
4KB Random READ 16.31 15.58 17.77
4KB Random WRITE 14.45 14.97 15.99
128KB Seq. READ 190.23 255.17 355.89
128KB Seq WRITE 345.21 342.99 313.98
bennymankin - Wednesday, April 6, 2011 - link
Please include Vertex 2 120GB, as it is probably one of the most popular drives out there.Thank you.
kensiko - Thursday, April 7, 2011 - link
The F120 does it, but true it's not the 25nmShark321 - Friday, April 8, 2011 - link
I concur. Vertex 2 120 GB should be compared to Vertex 3 120GB. I suspect the differences will be minimal on SATA II. It's basically the same product, with slight controller and firmware changes.