Introduction and Specifications
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. The new drives are members of SanDisk’s Extreme II family of products and target PC enthusiasts, gamers, and multi-media aficionados.
We’ve got a trio of SanDisk’s Extreme II drive in hand and will how you how they perform versus a number of competing products on the pages ahead. Before we get to the numbers though, below are the main features and specifications for the SanDisk’s Extreme II drives, followed by a teardown of one of one of the drives. Check out the good and then we’ll move on and see how the drives measure up...
The initial line-up of SanDisk Extreme II solid state drives will consist of 120GB, 240GB, and 480GB 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 three drives at 545MB/s – 550MB/s. Write performance between the 240GB and 480GB drives differs by only 10MB/s (510MB/s vs. 500MB/s), though the 120GB drive tops out at 340MB/s.
All three of SanDisk’s initial Extreme II 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 19nm eX2 ABL MLC NAND flash memory, an 8-channel Marvell 88SSS9187 controller with SATA 6Gbps interface, and a DDR3 DRAM cache. The 120GB drive features 128GB of total NAND flash memory, the 240GB drive features 256GB, and the 480GB drive features 512GB. 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 128MB, 256MB, and 512MB capacities for the 120GB, 240GB, and 480GB drives, respectively.
In addition to the DRAM cache, SanDisk also employ a proprietary technology dubbed nCache in the Extreme II 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.
SanDisk is going to be offering a couple of different configurations of their Extreme II drives at retail, with bundles that target different users. The drives included in the kits are identical, but there will be versions offered for notebook and desktop users. The notebook kits come bundled with a 7mm to 9.5mm shim, while the desktop bundle includes a 2.5” to 3.5” mounting bracket, screws, and a SATA cable.