SanDisk has been a leader in the storage industry for more than 20 years. Founded in 1988 by Dr. Eli Harari, the company has grown from a three-person Silicon Valley startup to the world's largest provider of flash memory storage solutions. The company offers a wide range of products including memory cards, USB flash drives, SSDs and its popular line of Sansa music and video players.
The latest addition to SanDisk's line of consumer-oriented solid state drives is the Ultra II. This easy, affordable upgrade solution is available in capacities ranging from 120GB up to a massive 960GB, and, depending on the capacity, is powered by one of two controllers from Marvell. Where the 120GB and 240GB versions of the drive are equipped with the 4-channel 88SS9190, the 480GB and 960GB versions get the 8-channel 88SS9189. The Ultra II is also the first SSD from SanDisk to use TLC NAND flash. While this high-density NAND is more affordable than the MLC Toggle NAND flash found in SanDisk's Extreme Pro SSD, there is a bit of a trade off in regards to endurance (program/erase cycles) and performance.
To overcome the challenges associated with TLC NAND flash, the Ultra II utilizes a tiered caching system which combines a sizeable DRAM cache with SanDisk's nCache 2.0 technology. This new version of nCache improves write performance and endurance by minimizing write amplification on the TLC NAND flash.
With nCache 2.0, data is first written to the SLC blocks. When the SLC blocks are partially full, data is copied from there to TLC blocks. This copy operation is done using the NAND's On Chip Copy feature, which is capable of copying data inside the NAND without needing to use the controller or the DDR DRAM cache. During this process, On Chip Copy takes three SLC blocks and folds them into a single SLC block. These blocks are written sequentially, resulting in optimized write amplification (< 1).
The Ultra II also incorporates what SanDisk calls Multi-Page Recovery (M.P.R). Intended as a last line of data protection, Multi-Page Recovery uses page-level striping to recover errors that could not be corrected by other traditional means.
For this review, we purchased the 240GB version of the Ultra II. This drive is capable of delivering up to 550 MB/s sequential read and 500 MB/s sequential write speeds as well as up to 91,000 random read and 83,000 random write IOPS.
|SanDisk Ultra II 240GB Solid State Drive|
Dimensions and Weight
Needless to say, this is only a taste of what the Ultra II has to offer. To give you an idea of what to expect, we'll take a closer look at SanDisk's new SSD and then see how well it performs. Does the Ultra II have what it takes? Is it the best bang for your buck? Keep reading as we find out.