As the cost of solid-state drives falls, SSDs have become a more cost-effective way to increase performance-hungry enterprise applications' response times. There are important differences between SSD products, and between SSDs and their magnetic counterparts, so cost alone shouldn't drive purchasing decisions. First, flash-based hard drives wear out because the oxide layer that stores its binary data degrades with every program/erase (P/E) cycle. All SSDs use NAND flash; some use the more durable SLC NAND, while others use the less expensive MLC NAND. Most SLC memory supports about 50,000 P/E cycles, while MLC generally lasts about 5,000 cycles. Drive vendors employ "wear-leveling" techniques that spread P/E cycles across all cells to prolong a drive's usable life.
As Storage Week 2013 continues, the CRN Test Center evaluates five solid-state drives that recently hit the market, sizing up their place in the enterprise. All drives conform to the 2.5-inch form factor and comply with the SATA 3.0 specification, which performs at a maximum theoretical transfer rate of 6 Gb/s.