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OCZ's Vertex 3 Pro: Second-Gen SandForce Perf Preview

OCZ's Vertex 3 Pro: Second-Gen SandForce Perf Preview
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Intel's X25-M revolutionized the SSD market. But then SandForce turned it upside down, coming out of nowhere to establish a dominant position. Today we see the company preview its second-generation controller, unleashed over a native 6 Gb/s interface.

Back in September of last year, we previewed OCZ’s high-speed data link technology in OCZ's HSDL: A New Storage Link For Super-Fast SSDs. This is a PCI Express-based interconnect designed to overcome the limits of conventional SAS and SATA. The argument was that both serial interconnects, which now top out at 6 Gb/s, artificially limit what today's fastest NAND flash devices are capable of.

Granted, most folks are still limited to SATA 3Gb/s. Intel only just added 6 Gb/s support to its problematic Cougar Point chipsets, while AMD's SB850 has offered that capability for a little while longer. But it's not like 3 Gb/s signaling is really holding most of us back anyway. Before the 6 Gb/s interfaces make real sense as differentiators, we need more storage devices capable of saturating the ~300 MB/s a 3 Gb/s link theoretically enables.

Right now, there is a mad rush to bring those next-generation 6 Gb/s devices to market. Crucial's C400 is expected to emerge within the next month and a half. Intel's SSD 510-series drives are just over the horizon as well. But OCZ beat both competitors to getting actual drives into our hands for a performance preview. The Vertex 3 Pro we have is admittedly pre-production and intended for an enterprise audience. But at the end of the day, those are the environments that stand to gain most immediately from a transition to higher-performance storage. And of course, we will be seeing consumer-level drives based on this same technology before long.

OCZ's Vertex 3 Pro specs, based on SandForce's new and highly-anticipated SF-2582 controller, greatly exceed the only other currently-available 6 Gb/s SSD, Crucial's C300--and not by a slim margin. OCZ is citing sequential reads of up to 550 MB/s and writes as high as 500 MB/s, with 70 000 IOPS in random 4 KB writes.

Flash Memory: SLC & MLC

With the next generation of SSDs on the horizon, it makes sense to cover the basics on how NAND flash works. The typical system memory that we rely on for temporary storage between the drives and our processor (generally DDR3 in today's systems) is volatile in that it requires power for data retention. Once you shut down your computer, all the information in RAM is lost. NAND flash is different. It is non-volatile memory. When you write to a solid-state drive, it holds the data, even after you power down your computer. Unlike platters inside a hard drive, flash memory's ability to hold a charge gives out if it is erased too many times.

There are two main types of NAND memory used in today's SSDs (four if you count eSLC and eMLC but we will save that for another day): Single-Level Cell (SLC) and Multi-Level Cell (MLC). At the manufacturing level, both are nearly identical. The difference is in how data is stored, and that in turn affects performance, reliability, and cost.

A flash cell is made up of a single transistor, with an additional "floating" gate that stores electrons. These electrons are the result of an electrical field generated from the large voltage difference between the drain the and source. This field is what allows the nonconductive silicon substrate to function as a conductive channel. The idea is that, as electrons flow through the channel, the field is used to bump electrons up to the floating gate. However, even as the electron travels down the channel, gaining momentum, the energy gained is insufficient to push the electron onto the gate. Those electrons that already have a high momentum approaching the gate can end up being bumped up into the gate by first hitting a silicon atom within the channel. It is the number of electrons in the floating gate that affects the voltage of the cell, and voltage is used to determine the cell's state.

SLC Levels
Value
State
0
Programmed
1
Erased


How does this relate to data? Single-Level Cell flash stores one bit per cell. It is a single-bit binary system. It is either a "0" or a "1." Since states are dependent on voltage, the electrical charge you induce on the floating gate affects the state.

In the diagram, the threshold voltage occurs at 4.0 V. Above 4.0 V, the cell will read as holding data. 

MLC Levels
Value
State
00
Completely Programmed
01
Partially Programmed
10
Partially Erased
11
Completely Erased


If a Single-Level Cell holds one bit per cell, then a Multi-Level Cell obviously holds more than one. As shown in the table, we now are looking at two bits per cell. This comes out to four states. While that sounds great on paper, there is a cost to increasing storage density.

Flash memory only has so much voltage tolerance. You can't just double the voltage to multiply the scale. Instead, you need more sensitively between each state. This means more programming to manipulate a very precise amount of charge stored in the floating gate. MLC works in the same way SLC does, but with greater precision on charge placement and charge sensing. 

Comparison of SLC and MLC (3x nm)

SLC
MLC
Bits/Cell
1
2
Density
16 Gb
32 Gb
Read Speed
100 ns
120 ns
Block Size
64 Kb
128 Kb
Endurance
100 000 cycles
3 000 cycles
ECC Capability
8 b/512 B
24 b/1 KB
tPROG
0.5 ms
1.2 ms
tERASE
1.5 - 2 ms
3 ms
Operating Temp
Industrial
Commercial


All of this means that you can use the same wafer size and get double the density with MLC. Of course, there is a penalty. First, accelerated degradation of the silicon channel is responsible for the lower endurance of MLC-based flash. This occurs because there is more activity, as it needs to pass different charges with greater frequency. Second, as you increase the precision, performance is affected. Remember that storing one bit is straightforward. The cell just has to be above or below 4 V.

SSDs (at least so far) only employ two-bit per cell MLC. As you keep increasing the density, you have to give up more and more performance and endurance, which is why three-bit per cell MLC is not what vendors call compute-quality yet. It's only used in devices like USB flash drives, removable flash cards, and portable media players.

Display 35 Comments.
  • 1 Hide
    karma831 , February 18, 2011 4:08 AM
    Performance looks great but I don't think the price will be.
  • 0 Hide
    Bigmac80 , February 18, 2011 4:18 AM
    This is why i haven't bought a SSD yet. One it's freakin expensive 2 not enough capacity 3 it's freakin expensive! It'll go down next year when the world ends in 2012.
  • 1 Hide
    falchard , February 18, 2011 4:33 AM
    Price is lower then last generation. A shrink in die size means cheaper manufacturing costs, lower power usage, and better performance. Thats what happens when every hardware company shrinks their chips.
    Considering this is going to have the same amount of space, its going to be a cheaper SSD.
  • 1 Hide
    Scanlia , February 18, 2011 5:03 AM
    500MB/s... wow
  • 0 Hide
    aaron88_7 , February 18, 2011 5:53 AM
    These are for enterprise use, that's why they are priced so high. They have features average consumers don't need. In other words, you're wasting your money if you are putting these into your home computer.
  • 0 Hide
    dragonsqrrl , February 18, 2011 6:31 AM
    OCZ Vertex 3 Pro MSRP Pricing:
    100GB: $525, $5.35 per GB
    200GB: $775, $3.88 per GB
    400GB: $1350, $3.38 per GB

    Getting cheaper, but still far outside my price range given their relative capacities. Even taking their amazing performance into account, it's still going to be a difficult sell for all but the most passionate enthusiasts, pros with heavy server workloads, or hardcore idiots. You're definitely not going to be getting your moneys worth putting one of these into your gaming rig. Enterprise type applications experience the largest benefits from these types of drives, and it's probably the only application where the performance benefits balance out the higher costs.
  • 0 Hide
    JohnnyLucky , February 18, 2011 9:15 AM
    The article made it perfectly clear the drive is not a drive that will be offered to consumers, gamers, and pc enthusiasts. How is OCZ going to reduce prices for consumer drives? Reduce features? Cut corners? Replace high quality components with lesser quality components? On answer is OCZ will reduc features. I'd like to know what else OCZ is going to do.
  • 1 Hide
    Anonymous , February 18, 2011 9:34 AM
    Please add a TrueCrypt benchmark to your SSD evaluations, for two reasons. First, the difficulty of truly erasing data on a flash drive makes data security more important. Second, there are drives (like Sandforce) that use compression and may behave differently when storing encrypted (high entropy) data.
  • 0 Hide
    nikorr , February 18, 2011 9:36 AM
    About time
  • -1 Hide
    Miharu , February 18, 2011 10:51 AM
    Presently Plextor M2-M2S offer 370-420MB/s read for what... (64gb)150$-(128gb)250$. Vextor 3 price is out of the loop, it's too expensive. At this price I can buy 2 Plextor and put them in RAID 0.
  • 0 Hide
    alidan , February 18, 2011 10:58 AM
    THANK YOU

    you finaly put normal hdds in a ssd review with tests, its nice to see the comparison.

    now i do hate to ask this... but until SATA 6 Gb/s hit the market big, can we get the drive also tested in a SATA 3 Gb/s configuration? this would be largely bennifitial to people to know. because im assuming that even with the 3's limited bandwidth, some operations will still be faster between the two
  • 0 Hide
    sirmaster , February 18, 2011 12:43 PM
    I just got a 256GB Mushkin IO SSD directly from the Mushkin store for $200.
    http://www.mushkin.com/Digital-Storage/SSDs/MKNSSDIO256GB.aspx

    It sold out pretty fast though.

    But it was under $1 per GB finally. It's not blazing like this drive but its about 250MB/s read and 180MB/s write with 20,000 IOPS. Considering it's 4x cheaper for the capacity compared to this drive I think it was worth it.
  • 0 Hide
    dimar , February 18, 2011 12:46 PM
    Didn't see the new Plextor drives when I was ordering Corsair Performance 3 128GB SSD at newEgg. Well... I'm pretty happy with it anyway. Hope the day comes soon when regular HDDs will be remember as much as music tapes today :-) and where 2TB 1GB/s SSDs are standard :) 
  • 0 Hide
    saint19 , February 18, 2011 1:05 PM
    uhmm where is the C300?
  • 1 Hide
    Anonymous , February 18, 2011 1:12 PM
    You have to multiply the power (watts) by the time it took in order to get a meaningful, comparable number (energy).
  • 0 Hide
    Figaro56 , February 18, 2011 1:24 PM
    Why did the review have comparison against the other top SATA 6 drive out there today, EG, Crucial C300? Very odd.
  • 0 Hide
    Figaro56 , February 18, 2011 1:27 PM
    I agree, where is the Crucial C300. Go to Anandtech, they show the C300 in their review. If you own a C300 you will happy to see that it is still a relevant SSD. The Vertex 3 doesn't blow it away.
  • 0 Hide
    TeraMedia , February 18, 2011 1:42 PM
    I second ChrisHF. Power is free. It's energy that costs money and raises temperatures inside a PC case. Please include either Joules (1 Watt = 1 Joule / second), Wh (3600 Joules) or kWh (3.6 M Joules) in your discussions about energy consumption. You always end up having to note that something uses more power but finishes faster... by graphing the relative energy consumption rather than the power consumption, you automatically resolve this confusion.

    Other than that, thanks for the article. If anything, hopefully the faster high-end devices will cause lower-end devices to reduce in price just like what happens with CPUs. I can only hope.
  • 1 Hide
    dark_lord69 , February 18, 2011 2:10 PM
    I really like the performance specs but those prices are painful!
  • 0 Hide
    hardcore_gamer , February 18, 2011 4:09 PM
    The diagram of flash transistor is missing the SiO2 layer
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