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Corsair's Neutron Series XT solid-state drive reviewed

My SSD controller has more cores than yours
— 8:00 AM on November 17, 2014

Corsair's Neutron Series is developing a habit of introducing us to new SSD controllers. The initial members of the family were the first consumer-oriented drives to feature Link_A_Media Devices' LM87800, a good all-around performer that's particularly adept at handling more demanding workloads. Today, the new Neutron Series XT provides our first look at Phison's latest PS3110-S10 controller.

Like LAMD, Phison isn't exactly a household name. The Taiwanese firm has been around for ages, though, and its previous PS3108 controller can be found in several value-oriented SATA SSDs, including Corsair's Force Series LS. The PS3110 adds more horsepower along with enterprise-friendly features intended to push Phison into the realm of high-end PCs and entry-level servers.

Phison's ambitions aren't lost on Corsair, which says the Neutron Series XT was "designed for the absolute best in class performance" for a SATA SSD. Since we've tested pretty much every high-performance SATA drive out there, it's only appropriate that we see how the XT compares.

Quad cores meet A19 NAND
Like just about every other SSD controller, the PS3110 has a 6Gbps host link and an eight-channel NAND interface. But unlike its peers, which typically have no more than three processor cores, the chip is a full-blown quad. Three of its four cores are devoted exclusively to flash management chores like background garbage collection. Phison claims this additional horsepower lowers command latencies and helps to improve performance with sustained workloads and when the drive is nearly full.

Consumer drives are often filled close to capacity, but the associated workloads are usually very bursty in nature. Sustained I/O is typically confined to servers, where some of the controller's other perks should be appreciated. The PS3110 boasts end-to-end data protection that performs error detection correction between the drive's controller, DRAM cache, and NAND storage. The controller also has a Smart ECC scheme that uses RAID-like parity to recover from uncorrectable errors caused by flash failures.

Phison's SmartFlush feature aggressively pushes in-flight data to the flash in order to minimize the chance of data loss due to unexpected power failures. The Neutron Series XT doesn't appear to have capacitors devoted to keeping the lights on, though. Consumer-oriented SSDs like this one rarely feature robust power-loss protection.

256-bit AES encryption support is pretty common even on consumer-grade drives, and the PS3110's implementation is compliant with the TCG Opal 2.0 spec. Unfortunately, the spec sheet doesn't mention the IEEE 1667 credentials required by Microsoft's eDrive standard.

On the flash front, the PS3110 supports the current generation of "1y" nanometer NAND along with next-gen chips fabbed with "1z" tech. The controller can address the NAND in MLC or TLC mode, which is a notable change from the MLC and SLC configs available with Phison's previous SSD controller. Trading SLC for TLC makes a lot of sense for consumer-grade drives. Swapping one bit for three also has some appeal for entry-level servers, since those machines are unlikely to require ultra-high-endurance flash. In fact, Samsung is already selling budget server SSDs with TLC NAND.

In the Neutron Series XT, the Phison controller is paired with the "A19" variant of Toshiba's 19-nm MLC NAND. SSDs generally use the same NAND throughout the line, but the XT employs different die sizes depending on the total capacity. The 240GB and 480GB variants sport 8GB chips, while the 960GB flagship has larger 16GB ones.

Having more, smaller dies is preferable in lower-capacity SSDs because it allows the controller to flex more of its internal parallelism. Most SSD controllers require at least 32 dies to achieve peak performance, and at 8GB per die, even the XT 240GB has sufficient NAND to hit top speed. Corsair's "internal performance metrics" suggest the base model should have no problem keeping up with its larger siblings.

Capacity Die config Max sequential (MB/s) Max 4KB random (MB/s) Endurance
Read Write Read Write
240GB 32 x 8GB 564 547 391 378 124TB
480GB 64 x 8GB 562 542 404 361 124TB
960GB 64 x 16GB 562 532 384 357 124TB

Corsair doesn't list random 4KB IOps for each capacity, but it does indicate that the family hits "up to" 100k IOps with reads and 90k IOps with writes. You can work backwards from the MB/s totals to get the number of 4KB IOps.

I'll do the math for the endurance spec: the Neutron Series XT is rated for 124TB of total writes, which works out to 70GB per day for the length of the five-year warranty. The terabyte total is fairly generous, and the five-year coverage matches the warranty attached to Corsair's other Neutron SSDs. (Corsair initially indicated that the XT had a three-year warranty, but the company has since clarified that the coverage lasts for five years.)

Users can monitor drive wear by checking the SMART attributes with third-party software or Corsair's own SSD Toolbox utility. In addition to providing an overall health rating, the attributes track bad blocks, host writes, and both program and erase errors. Too bad there's no decoder ring for the vague "vendor specific" variables.

The Toolbox utility performs other functions, such as applying firmware updates, cloning drive contents, optimizing Windows settings, and completing secure erase procedures. It's not the fanciest SSD software around, but it's unobtrusive, and it covers all the important bases.

Before we dive into our performance results, I have to take a moment to highlight a somewhat mundane detail. But there's a certain elegance to the XT's two-piece chassis, which sandwiches the drive without a single screw. Even with the top popped off, the circuit board is held in place by little nubbins that poke in from the sides.

The simplified clamshell is surely a cost-cutting measure, as is the stubby circuit board that sits inside. Given the extremely price-competitive nature of the consumer SSD market, it's easy to see why Corsair might want to shave pennies wherever it can—not that there's anything wrong with that. The case still feels solid, and the brilliant red paint adds a dash of 'zazz.