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OCZ's Vertex 4 solid-state drive

A sort of homecoming

OCZ's original Vertex wasn't the first SSD on the market, but it deserves a lot of credit for popularizing solid-state drives among enthusiasts. The first iteration debuted in late 2008 with an Indilinx Barefoot controller that offered much better performance than the flaky JMicron chip making the rounds at the time. Although the 120GB drive's $470 price tag seems high by today's standards, it was a bargain compared to Intel's X25-M, which cost more but offered just 80GB of storage. The Vertex also gained TRIM support via a firmware update, while Intel famously reserved that feature for its second-gen X25-M.

Since its arrival, the Vertex has spawned multiple models distributed across a several generations. About a year after the first Vertex arrived, OCZ ditched Indilinx for a new muse. SandForce's SF-1200 controller served as the basis for the Vertex 2, and one year after that, the SF-2200 controller brought 6Gbps Serial ATA connectivity to the Vertex 3. Now, it's time for round four.

Rather than sticking with SandForce, the Vertex has fallen back into the arms of its first love. OCZ actually bought Indilinx last March, so the relationship is much closer now. Less than nine months after the acquisition, the OCZ Octane SSD arrived with a new Indilinx Everest controller onboard. A second-generation version of that controller, dubbed Everest 2, now provides the foundation for the Vertex 4.

The Octane is a solid drive, with competitive performance and a seemingly decent reliability record, so there's reason to be optimistic about the new Vertex. This latest offering features numerous hardware and firmware changes that promise better performance and improved endurance. Let's see what it can deliver.

Introducing the second child
Modern SSDs are made up of three primary components: the controller, the NAND flash, and the firmware that ties them together. OCZ controls the first and last elements, and those are the areas in which the Vertex 4 differs the most from the Octane. Let's start with the controller, which takes center stage on the drive's circuit board. Seriously, it's right in the middle of the action:

Most SSDs put the controller closest to the SATA connector, with the NAND chips arranged in an orderly grid below. The Octane follows that layout, but the Vertex arranges the NAND in a sort of ring around the controller. This arrangement was designed to make the trace lengths between the controller and the NAND more consistent; in typical SSD configurations, some NAND packages are much farther from the controller than others.

Another notable feature of the board is the array of "golden fingers" located along its bottom edge. The pattern looks like it might be a match for the mSATA interface, but OCZ tells us this is simply a connector for its internal debugging tools. Alas, you won't be able to overclock the drive by flipping a few DIP switches. There's no need to, anyway, because OCZ has turned up the clocks itself.

The Everest controller in the Octane runs its dual ARM cores at "less than 300MHz," according to OCZ. In Everest 2, those cores are clocked at a speedier 400MHz. The gen-one chip's 6Gbps Serial ATA interface remains, as do its eight memory channels. The 65-nm fabrication process used to manufacture the chip is unchanged, as well. 256-bit AES encryption support? Check.

Everest 2 does feature a new error correction engine, which OCZ credits for improving the Vertex 4's NAND endurance. This programmable ECC block can be tuned to match the "specific error characteristics" of different flash flavors. NAND built on finer fabrication processes is more prone to errors and can typically withstand fewer write/erase cycles, making robust error correction an increasingly important feature for SSDs.

The new ECC engine is a big part of nDurance 2.0, a collection of technologies focused on extending drive life. We first heard about nDurance when it was introduced with the Octane as a "highly integrated and complementary solution set of NAND flash management techniques." OCZ wouldn't say more at the time, but it contends that version 2.0 is better, of course. This latest iteration purportedly gives the Vertex 4 a much lower write amplification factor than the Octane. OCZ achieved this feat without resorting to compression. Instead, the nDurance 2.0 concatenates multiple write requests and attempts to reduce the number of unnecessary copy-back operations.

The Vertex 4's actual write amplification factor will depend on the workload, but OCZ says it should be lower than on any other SSD with the same 7% overprovisioning percentage, including those based on SandForce controllers. That would be an impressive feat considering the compression voodoo built into the last couple of generations of SandForce chips.

Another component of nDurance 2.0 is RNA, otherwise known as Redundant NAND Array. This programmable redundancy scheme protects against physical flash failures by striping data and the associated parity bits across multiple flash cells. Like similar redundancy schemes offered by other SSDs, RNA can survive the death of up to a single flash die without losing the user's data. The distributed parity bits do consume some of the NAND capacity, though. Redundancy is never free.