Introduction and Specifications
When we took at look at SanDisk's Extreme II series of solid state drives in June of last year, we began our article by noting, "odds are, if you’ve bought anything that uses flash memory in the last 20 years or so, you already own a small piece of SanDisk technology. The company has been a leader in flash memory storage since the late ‘80s and manufactures products used in everything from smartphones and portable media players to digital cameras and camcorders. With such a long history in the flash memory business, it’s should be no surprise that SanDisk offers an array of solid state storage solutions for desktop and mobile PCs as well. In fact, SanDisk recently expanded their product stack with some new, high-performance SSDs that leverage the company’s own NAND flash memory and Marvel’s popular 88SSS9187 controller." All of that still applies today, as we present to you SanDisk's follow-on product, the Extreme Pro series.
The SanDisk Extreme Pro series of solid state drives features much of the same technology as its predecessor, but it has been updated with newer NAND and a refined firmware that kicks performance up a notch. And while endurance ratings haven't changed, SanDisk shows supreme confidence in these drives by offering an industry-leading 10 year warranty.
The initial line-up of SanDisk Extreme Pro solid state drives will consist of 240GB, 480GB, and 960GB models. The specifications for the three drives are listed in the chart above, and we’ll be testing all three on the pages ahead. As you can see in the chart, expected read performance is similar for all of the drives at 550MB/s. Write performance between the drives differs a bit, however, with the 240GB model coming in at 520MB/s and the other at 515MB/s.
All three of SanDisk’s initial Extreme Pro series drives conform to the standard 2.5” form factor and are only 7mm thick. They have basic enclosures made of a plastic composite material, with decals top and bottom—one with the branding on top and another on the bottom that lists the drive specifications and model numbering, etc.
Inside the drives you’ll find an array of SanDisk-made second-gen 19nm eX2 ABL MLC NAND flash memory, an 8-channel Marvell 88SSS9187 controller with SATA 6Gbps interface, and a DDR3 DRAM cache. The 240GB drive features 256GB of total NAND flash memory, the 480GB drive features 512GB, and the 960GB drive features 1024GB. The additional ~7% of unused NAND is reserved for wear leveling and other maintenance operations. The size of the DRAM cache on the drives differs as well, with 256MB, 512MB, and 1GB capacities for the 240GB, 480GB and 960GB drives, respectively.
In addition to the DRAM cache, SanDisk also employ a proprietary technology dubbed nCache Pro in the Extreme Pro drives. The nCache is actually a chunk of the MLC NAND that operates in an SLC-like mode. SanDisk’s nCache technology accumulates small writes in the non-volatile nCache, and consolidates them before flushing them to the larger MLC NAND flash. This multi-tiered caching approach is designed to improve random write performance and increase the drive’s endurance. Speaking of endurance, SanDisk rates all of the drives at >80 TBW (terabytes written) with a 2M hour MTBF.