SanDisk's Extreme II series is their Enthusiast Class SSD. SanDisk designed the Extreme II to take on all comers performance wise as well as provide unmatched endurance capabilities by lowering write amplification. SanDisk utilizes the finest components in the Extreme II. While other manufacturers are trending toward inferior TLC (Triple Level Cell or 3-bit-per-cell) NAND implementation, SanDisk is utilizing premium MLC (Multi Level Cell or 2-bit-per-cell) 19nm DDR NAND Flash to power the Extreme II. This is not just some ordinary 19nm flash; this flash has an emulated SLC (Single Level Cell) layer baked right in. SanDisk calls this emulated SLC technology "nCache".
So, what is SLC emulation and why does it matter? 1-bit-per-cell NAND (SLC) is the "good stuff" because it has vastly superior performance and longevity in comparison to (MLC) 2-bit-per-cell or (TLC) 3-bit-per-cell NAND technology. Programming a single bit-per-cell can be accomplished at a much lower latency than programming multiple bits-per-cell, and is the reason SLC NAND provides superior performance. SLC NAND is typically rated for 100K P/E (Program/Erase) cycles whereas MLC/TLC NAND is rated for 0.5K to 5K P/E cycles. The drawback to SLC NAND implementation is cost. SLC NAND is in order of magnitude more expensive to fabricate than MLC or TLC NAND. SanDisk came up with a brilliant technology called "nCache".
nCache Technology allows a layer of an MLC NAND array to be programmed as single bit-per-cell. This pseudo SLC layer has lower latency and greater endurance than the rest of the MLC NAND array. nCache Technology is used to accumulate small writes (called segments) at high speed and then flush and consolidate them to the larger MLC section of the NAND Flash memory array, thereby greatly reducing write amplification. Reducing write amplification is the key to an MLC based drive's longevity, reliability, and long term performance.
The Extreme II has at its heart Marvell's third generation 88SS8197 Flash Storage Processor. Dubbed "Monet," this processor is capable of 200 MB/s per channel internally as well as unparalleled correction capabilities due to its high performance ECC engine with Adaptive Read and Write Scheme, on-chip RAID functionality, and open architecture. An open architecture will allow SSD manufacturers to fully customize their products to meet specific customer demands and distinguish their products based on price, performance, power and functionality. Open architecture also allows SanDisk to fully customize firmware to their own specifications and even introduce innovations like "nCache".
Today we've got two and three drive Extreme II array's running balls out in RAID 0 for your viewing pleasure. Let's see how SanDisk's current Enthusiast series drives perform in RAID 0 powered by Intel Haswell ports and Microsoft Windows 8.1.