The OCZ Vertex 3 Review (120GB)
by Anand Lal Shimpi on April 6, 2011 6:32 PM ESTThe NAND Matrix
It's not common for SSD manufacturers to give you a full list of all of the different NAND configurations they ship. Regardless how much we appreciate transparency, it's rarely offered in this industry. Manufacturers love to package all information into nice marketable nuggets and the truth doesn't always have the right PR tone to it. Despite what I just said, below is a table of every NAND device OCZ ships in its Vertex 2 and Vertex 3 products:
| OCZ Vertex 2 & Vertex 3 NAND Usage | ||||
| Process Node | Capacities | |||
| Intel L63B | 34nm | Up to 240GB | ||
| Micron L63B | 34nm | Up to 480GB | ||
| Spectek L63B | 34nm | 240GB to 360GB | ||
| Hynix | 32nm | Up to 120GB | ||
| Micron L73A | 25nm | Up to 120GB | ||
| Micron L74A | 25nm | 160GB to 480GB | ||
| Intel L74A | 25nm | 160GB to 480GB | ||
The data came from OCZ and I didn't have to sneak around to get it, it was given to me by Alex Mei, Executive Vice President of OCZ.
You've seen the end result, now let me explain how we got here.
OCZ accidentally sent me a 120GB Vertex 2 built with 32nm Hynix NAND. I say it was an accident because the drive was supposed to be one of the new 25nm Vertex 2s, but there was a screwup in ordering and I ended up with this one. Here's a shot of its internals:
You'll see that there are a ton of NAND devices on the board. Thirty two to be exact. That's four per channel. Do the math and you'll see we've got 32 x 4GB 32nm MLC NAND die on the PCB. This drive has the same number of NAND die per package as the new 25nm 120GB Vertex 2 so in theory performance should be the same. It isn't however:
| Vertex 2 NAND Performance Comparison | ||||
| AT Storage Bench Heavy 2011 | AT Storage Bench Light 2011 | |||
| 34nm IMFT | 120.1 MB/s | 155.9 MB/s | ||
| 25nm IMFT | 110.9 MB/s | 145.8 MB/s | ||
| 32nm Hynix | 92.1 MB/s | 125.6 MB/s | ||
Performance is measurably worse. You'll notice that I also threw in some 34nm IMFT numbers to show just how far performance has fallen since the old launch NAND.
Why not just keep using 34nm IMFT NAND? Ultimately that product won't be available. It's like asking for 90nm CPUs today, the whole point to Moore's Law is to transition to smaller manufacturing processes as quickly as possible.
Why is the Hynix 32nm NAND so much slower? That part is a little less clear to me. For starters we're only dealing with one die per package, we've established can have a negative performance impact. On top of that, SandForce's firmware may only be optimized for a couple of NAND devices. OCZ admitted that around 90% of all Vertex 2 shipments use Intel or Micron NAND and as a result SandForce's firmware optimization focus is likely targeted at those NAND types first and foremost. There are differences in NAND interfaces as well as signaling speeds which could contribute to performance differences unless a controller takes these things into account.
25nm Micron NAND
The 25nm NAND is slower than the 34nm offerings for a number of reasons. For starters page size increased from 4KB to 8KB with the transition to 25nm. Intel used this transition as a way to extract more performance out of the SSD 320, however that may have actually impeded SF-1200 performance as the firmware architecture wasn't designed around 8KB page sizes. I suspect SandForce just focused on compatibility here and not performance.
Secondly, 25nm NAND is physically slower than 34nm NAND:
| NAND Performance Comparison | ||||
| Intel 34nm NAND | Intel 25nm NAND | |||
| Read | 50 µs | 50 µs | ||
| Program | 900 µs | 1200 µs | ||
| Block Erase | 2 µs | 3 µs | ||
Program and erase latency are both higher, although admittedly you're working with much larger page sizes (it's unclear whether Intel's 1200 µs figure is for a full page program or a partial program).
The bad news is that eventually all of the 34nm IMFT drives will dry up. The worse news is that the 25nm IMFT drives, even with the same number of NAND devices on board, are lower in performance. And the worst news is that the drives that use 32nm Hynix NAND are the slowest of them all.
I have to mention here that this issue isn't exclusive to OCZ. All other SF drive manufacturers are faced with the same potential problem as they too must shop around for NAND and can't guarantee that they will always ship the same NAND in every single drive.
The Problem With Ratings
You'll notice that although the three NAND types I've tested perform differently in our Heavy 2011 workload, a quick run through Iometer reveals that they perform identically:
| Vertex 2 NAND Performance Comparison | ||||
| AT Storage Bench Heavy 2011 | Iometer 128KB Sequential Write | |||
| 34nm IMFT | 120.1 MB/s | 214.8 MB/s | ||
| 25nm IMFT | 110.9 MB/s | 221.8 MB/s | ||
| 32nm Hynix | 92.1 MB/s | 221.3 MB/s | ||
SandForce's architecture works by reducing the amount of data that actually has to be written to the NAND. When writing highly compressible data, not all NAND devices are active and we're not bound by the performance of the NAND itself since most of it is actually idle. SandForce is able to hide even significant performance differences between NAND implementations. This is likely why SandForce is more focused on NAND compatibility than performance across devices from all vendors.
Let's see what happens if we write incompressible data to these three drives however:
| Vertex 2 NAND Performance Comparison | ||||
| Iometer 128KB Sequential Write (Incompressible Data) | Iometer 128KB Sequential Write | |||
| 34nm IMFT | 136.6 MB/s | 214.8 MB/s | ||
| 25nm IMFT | 118.5 MB/s | 221.8 MB/s | ||
| 32nm Hynix | 95.8 MB/s | 221.3 MB/s | ||
It's only when you force SandForce's controller to write as much data in parallel as possible that you see the performance differences between NAND vendors. As a result, the label on the back of your Vertex 2 box isn't lying - whether you have 34nm IMFT, 25nm IMFT or 32nm Hynix the drive will actually hit the same peak performance numbers. The problem is that the metrics depicted on the spec sheets aren't adequate to be considered fully honest.
A quick survey of all SF-1200 based drives shows the same problem. Everyone rates according to maximum performance specifications and no one provides any hint of what you're actually getting inside the drive.
| SF-1200 Drive Rating Comparison | ||||
| 120GB Drive | Rated Sequential Read Speed | Rated Sequential Write Speed | ||
| Corsair Force F120 | 285 MB/s | 275 MB/s | ||
| G.Skill Phoenix Pro | 285 MB/s | 275 MB/s | ||
| OCZ Vertex 2 | Up to 280 MB/s | Up to 270 MB/s | ||
I should stop right here and mention that specs are rarely all that honest on the back of any box. Whether we're talking about battery life or SSD performance, if specs told the complete truth then I'd probably be out of a job. If one manufacturer is totally honest, its competitors will just capitalize on the aforementioned honesty by advertising better looking specs. And thus all companies are forced to bend the truth because if they don't, someone else will.
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kensiko - Thursday, April 7, 2011 - link
It's true, I never saw any big company letting customers having so much impact on them. The forum is really the big thing here.lukechip - Wednesday, April 6, 2011 - link
I've just bought an 80GB Vertex 2. OCZ state that only "E" parts are affected, but at StorageReview, they show that they had a non "E" part which contained 25nm NAND. Also, OCZ say that the only parts affected are the 60 GB and 120 GB models.I've just purchased an 80 GB model, and have no idea what is inside it, nor whether I'd prefer it to be an 'old' one or a 'new' one.
The new SKUs that Anand listed indicate that moving forwards, all 80, 160 and 200 GB Vertex 2 units will be 25nm only, and all 60, 120 and 240 GB Vertex 2 units will be 34nm only. I can't imagine they can keep this up for long, as 34nm runs out and they have to move the 60, 120 and 240 GB models to 25 nm.
What I suspect is that prior to 25 nm NAND becoming available, all 80 GB units used the Hynix 32 nm NAND. Based on Anand's tests, I suspect this mean they were the worst performing units in the line up. 80 GB units built using the new 25 nm NAND would actually perform better than those built with Hynix 32 nm NAND.
So whereas 60 GB and 120 GB customers really want to have a unit based on 34 nm NAND, 80 GB customers like me really want to have a drive based on 25 nm NAND. Hence OCZ are not offering replacements for 80 GB units. A new 80 GB unit is better than an old 80 GB unit, even though it is not as good as an old 60 GB unit
So my questions are:
1/ Is what I am suggesting above true ?
2/ How can I tell what NAND I've got ? I've updated the firmware on my 80 GB unit soon after buying it, so the approach of using firmware version to determine NAND type doesn't seem too reliable to me ?
Personally, I find my unit plenty fast enough. And I understand that OCZ and other SSD vendors must accomodate what their suppliers present them with. However the lack of tranparency, and the "lucky dip" approach that we have to take when buying an SSD from OCZ lead me to conclude that they
1/ don't respect their customers and/or
2/ are very naive and stupid to expect that customers won't notice them pulling a 'bait and switch'
B3an - Thursday, April 7, 2011 - link
Anand... you seem to have forgotten something in your conclusion. You say it's best to go for the 240GB if torn between that and the 120GB. But being as two 120GB Vertex 3's are only very slightly more expensive than the 240GB version, wouldn't it make more sense to just get two 120GB's for RAID 0? Because you'd get considerably better performance than the 240GB then considering how well SSD's scale in RAID 0.Really great and interesting review BTW.
Alopex - Thursday, April 7, 2011 - link
I'd really like to see this question addressed, as well. According to several tests, SSDs scale in pretty much all categories after a minimal queue depth. It seems like the random reads here are the 120gb model's achilles' heel, but given the linearity of the scaling, it might be safe-ish to assume that 2x 120gb RAID 0 will equal 1x 240gb. For nearly the same price, it would then seem you get the same storage size, fixed the discrepancy between the two models, and hopefully see significant performance gains in the other categories like sequential read/write.I'm building a new computer at the moment, and in light of this article, I'm still planning to go with 2x 120gb Vertex 3s in RAID 0, unless someone can provide a convincing argument to do otherwise. At the moment, the only thing that really makes me hesitate is to see what the other vendors have planned for "next-gen" SSD performance. Then again, if I had that attitude I'd be waiting forever ;-)
Many thanks for the article, though!
casteve - Thursday, April 7, 2011 - link
No TRIM available in RAID.B3an - Thursday, April 7, 2011 - link
Not a big problem. I've had 3 different SSD sets in RAID 0 over the years, and i've not needed TRIM. And a certain crappy OS with a fruity theme dont even support TRIM without a hack job.ComputerNovice22 - Thursday, April 7, 2011 - link
You wrote "In the worst case comparison the F120 we have here is 30% faster than your 34nm Hynix Vertex 2."
I believe you meant 32nm Hynix, I'm not sure I'm right or not and I'm not trying to be one of those people that just likes to be right either, just wanted to let you know just in-case.
On another note though I LOVE the article, I bought a vertex 2 recently and I was very angry with OCZ after I hooked it up and realized it was a 25nm SSD ... I ended up just buying a 120Gb (510 elm-crest)
Lux88 - Thursday, April 7, 2011 - link
1. Thank you for investigating NAND performance so thoroughly.2. Thank you for benching drives with "common" capacities.
3. Thank you for protecting consumer interests.
Great article. Great site. Fantastic Anand.
sor - Thursday, April 7, 2011 - link
I worked at a Micron test facility years ago. I can only speak for DRAM, but I imagine NAND is much the same. Whenever someone drops a tray of chips and they go sprawling all over the floor... SpekTek. Whenever a machine explodes and starts crunching chips... SpekTek. I used to laugh when I saw PNY memory in BestBuy with a SpecTek mark on its chips selling for 2x what good RAM at newegg would cost.Basically anything that's dropped, damaged, or doesn't meet spec somehow, gets put into SpecTek and re-binned according to what it's now capable of. It's a brand that allows Micron to make money off of otherwise garbage parts, without diluting their own brand. On the good end the part may have just had some bent leads that needed to be fixed, on the bad end the memory can be sold and run at much slower specs or smaller capacity (blowing fuses in the chip to disable bad parts), or simply scrapped altogether.
sleepeeg3 - Thursday, April 7, 2011 - link
Thanks for the info, but IMO the bottom line is if it works reliably and it allows them to deliver something at a lower price, I am all for it. If it backfires on them and they get massive failure rates, consumers will respond by buying someone else's product. That's the beauty of capitalism.