Inside the Vertex 4

At a high level, Everest 2 is architecturally very similar to its predecessor. The SoC is still built on a 65nm G process and maintains the same basic architecture. Clock speeds are up now from 333MHz to 400MHz. There are also microarchitectural tweaks at work here – limits in Everest 1 have since been removed for Everest 2. Everest 2's sequencer is much improved, but getting more detail than this is basically impossible.


Everest 1's Block Diagram, Similar to Everest 2

Just as with previous OCZ drives, the Vertex 4 ships with its own custom designed PCB. Unlike most SSDs we've seen, the Vertex 4 places its Everest 2 controller in the center of the PCB – with NAND fanning out in a circle around it. The Indilinx SoC uses the drive housing as a heatsink as two thermal pads help conduct the heat away from the chip:


OCZ Vertex 4 512GB

In the 512GB version we find quad-die packaged Intel 25nm synchronous MLC NAND devices, sixteen of them in total. The 256GB version keeps the same number of devices but drops the die count per package from 4 to 2. Despite launching with Intel NAND, OCZ claims broad support for Flash from other vendors. Touting that advantage really only matters if there's cheaper NAND available on the market, today Intel NAND is still priced competitively enough to make it an obvious fit.


OCZ Vertex 4 512GB

OCZ is currently testing 20nm Intel NAND and 24nm Toggle Mode NAND with the Everest 2. Both are functional at this point, but neither is optimized in the current firmware. Should Toggle Mode NAND pricing or performance offer a measurable advantage, OCZ will introduce a separate product based on it. Currently, low-density 24nm Toggle NAND isn't price competitive and thus it's not used at launch. OCZ did add that a 1TB Vertex 4 would almost certainly use Toggle NAND as Toshiba's high-density pricing (64GB, octal die packages) is better than from IMFT these days. We're still at least a quarter away from seeing 20nm NAND used in volume, so enabling support for either of these options will require a firmware update.
With its sights fixed on OEMs, OCZ is far more concerned about drive longevity than it once was. OEMs don't like having to re-qualify components, they want a steady supply of the same product for the lifespan of whatever system they're selling. If a system is shipping to a government buyer, that lifespan can be extremely long. As a result, OCZ wanted to build a controller that was as forward looking as possible. Everest 2 needed to be able to migrate to 20nm without requiring another qualification pass from OCZ's customers. As NAND cell sizes shrink, error rates go up. Only so much can be dealt with at the NAND factory, the controller is extremely important to maintaining data validity.

The original Octane could correct up to 78 random bits for every 1KB of data using its BCH ECC engine. While that was more than sufficient for 25nm NAND, OCZ is planning for the future with Everest 2 and implemented a more robust ECC engine capable of correcting up to 128 random bits for every 1KB of data. OCZ believes the Everest 2's ECC capabilities are enough to ensure reliable operation with 20nm IMFT NAND and perhaps the first 1x-nm IMFT NAND as well. For consumers however, this has no bearing on the Vertex 4's performance/reliability as a drive today (Octane's ECC engine was enough).

1GB of DDR3-800 On-Board

The Everest 2 controller is flanked by a 512MB Micron DDR3-800 DRAM. Another 512MB chip exists on the flip side of the PCB bringing the total to a whopping 1GB of DDR3 memory on-board. OCZ makes no effort to hide the DRAM's purpose: Everest 2 will prefetch read requests from NAND into DRAM for quick servicing to the host. When serviced from DRAM, reads should complete as fast as the interface will allow it – in other words, the limit is the 6Gbps SATA interface, not the SSD.


OCZ Vertex 4 256GB

In order to get 128GB, 256GB and 512GB drives to market as quickly as possible, OCZ is shipping them all with 1GB of DRAM on-board. The 128GB and 256GB drives simply won't use all of the DRAM however. A future revision of the Vertex 4 will pair the 128/256GB drives with 512MB of memory instead to save on costs.


OCZ Vertex 4 256GB

The amount of memory bandwidth offered to the Everest 2 controller is insane – we're talking about 3.2GB/s, as much as many modern day smartphone SoCs, and as much as a desktop PC had a decade ago.

OCZ wouldn't tell me if the costs of shipping 1GB of DDR3 memory outweigh the savings from not having to pay SandForce for silicon anymore. Even though it owns Indilinx, R&D and manufacturing aren't free. All of that factored in, the cost of the Everest 2 controller is likely cheaper than SandForce's 2281, but it's not clear to me if the added cost of DRAM offsets that gap. None of this matters to end users, but it's an interesting discussion regardless. OCZ will have to deliver aggressive pricing regardless of its internal cost structure.

AES-256 Encryption

Similar to the Octane/Everest 1, all data written to NAND in the Vertex 4 goes through Everest 2's 256-bit AES encryption engine. Modern SSDs scramble data before writing to NAND to begin with (certain data patterns are more prone to errors in flash than others) and encryption offers security benefits in addition to working as a good scrambling engine. If you're going to support scrambling, the jump to enabling encryption isn't all that far.

Similar to other SSDs, the Vertex 4's encryption key is generated randomly at the factory. Unfortunately, also similar to other SSDs, there's no client facing tool to reset or manage the key. I believe the key is regenerated upon a secure erase and it can be tied to an ATA password, however what I'd really like to see is the bundling of a software package that can allow users to generate a new key and require a password at boot (not all ATA password implementations are super secure). I know there are third party applications that offer this functionality today, but I'd like to see something ship with one of these FDE drives by default so more consumers can actually use the feature. There's no point to having a self encrypting drive that gives up your data as soon as you plug it in to another system. While I'm making requests, I'd also like to see a way for OS X users to take advantage of built in full disk encryption.

Ndurance 2.0 and a 5-year Warranty

With Everest 2 OCZ supports redundant NAND arrays, similar to the latest Intel and SandForce controllers. By including redundant NAND on-board, the drive could withstand the failure of more than a single die without any data loss. The Vertex 4 doesn't have OCZ's redundant NAND technology enabled, although the enterprise version of the drive (Intrepid 3) will likely turn it on.

OCZ is also doing some granular manipulation of voltages at the NAND level in order to get the most endurance out of these drives (not all NAND is created equally, adjusting to characteristics of individual NAND devices can lead to more p/e cycles out of the drive). While this isn't really a concern for 25nm NAND on the Vertex 4 today, it is likely a feature we'll see played up with the move to 20nm and for eMLC versions of the drive targeted at the enterprise.

Confidence in reliability is at an all-time high with the Vertex 4 as it ships with a 5-year warranty, up from 3 years with the Octane, Vertex 2 and Vertex 3.

Introduction Random Read/Write Speed
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  • kristof007 - Thursday, April 05, 2012 - link

    I've been looking around for articles and just looked at bench marks (ignore the M3 and Vertex 4 reviews) and it seemed like the Crucial m4 was hands down the best drive. I purchased it yesterday via Newegg for $299 (it was on sale). Sounds like I won't be disappointed.

    I was wondering if you guys could maybe have like a top 3 list for SSDs (or heck .. for all categories) with quick pro's and con's for what is out at the moment and what is the best one performance wise.

    By the way, I haven't been reading much AT lately, but I've seen a few of your articles and would like to thank you for your work!
    Reply
  • nathanddrews - Wednesday, April 04, 2012 - link

    The 830 offers up nearly the best "real world" disk busy performance in both the light and heavy benchmarks and has proven to be extremely reliable and consistent without being very expensive. The M4 is great... but a bit outdated performance-wise (not as fast as the 830). Reply
  • antef - Wednesday, April 04, 2012 - link

    Thanks for the replies. I guess I saw them as trading places a good bit in the benchmarks, but I do see that the 830 often comes out on top. I guess I figured the performance difference is practically nil for mainstream uses and the M4 seems more highly reviewed. But the 830 has been out for less time, so that may improve over time. Reply
  • nathanddrews - Wednesday, April 04, 2012 - link

    That's just it - the differences in overall performance aren't likely to keep one awake at night. In the case of a person that has never used an SSD, just about any SSD available online today will completely shock and awe.

    An SSD that is 20% faster than another SSD which are both 900% faster than a 5400RPM HDD... not a big deal.
    Reply
  • antef - Wednesday, April 04, 2012 - link

    "Shock and awe" is the correct way to describe my feelings the first time I saw Windows boot in 3 seconds. :) Reply
  • beginner99 - Wednesday, April 04, 2012 - link

    Price wise for average user the m4 is the best bang for the buck. Here its the cheapest sata-3 128 GB drive and 20$ cheaper than the Samsung. Also m4 uses less power, eg better for a laptop. Reply
  • ExarKun333 - Wednesday, April 04, 2012 - link

    Looks like a trade-off that gave-up read performance for write performance with poor power consumption. Based on the charts, the HyperX 240GB or the Intel 520 would be better all-around options. The OCZ name also doesn't inspire a lot of confidence when it comes to reliability or support. They will really need up their game for customer service this generation to build some confidence in them. Reply
  • alan1476 - Wednesday, April 04, 2012 - link

    If you are not impressed by this drive the review did not do this drive justice. If someone reviews a drive especially an SSD you have to understand the inner workings and just how it applys itself to applications in the real world. This SSD is ground breaking. Reply
  • cknobman - Wednesday, April 04, 2012 - link

    I see no Sandforce 512gb drives shown in the performance charts.

    Its pretty common knowledge that SSD performance goes up with capacity and showcasing the Vertex 4 512gb drive against either smaller SSD's or older controllers makes it look better than it likely is.

    Did anyone notice the abysmal speeds for the 120gb model???
    I also noticed pretty high power consumption.

    I don't consider this review proper until you place a 2nd Gen 512gb SandForce drive in the charts to compare directly against the 512gb Vertex 4 drive.
    Reply
  • Kristian Vättö - Wednesday, April 04, 2012 - link

    240GB Vertex 3 is actually faster than 480GB Vertex 3:

    http://www.anandtech.com/bench/Product/352?vs=561
    http://www.ocztechnology.com/res/manuals/OCZ_Verte...
    Reply

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