Consumer adoption of Solid State Drives has been on the rise due to increasing competition and dropping prices. SSDs offer unparalleled random access times compared with traditional magnetic storage, but have the disadvantages of higher prices and lower capacities. Most consumer grade SSDs use Multi-Level Cell NAND flash in order to easily increase capacity and reduce costs.
One of the newer consumer grade SSDs has been OCZ's Vertex series, featuring maximum read speeds of 250 MB/s and maximum write speeds of 120 MB/s in the 120GB model. It uses a NAND flash controller from Indilinx in order to avoid problems with a stuttering effect present in older generation SSDs.
Although most recent SSD launches have targeted consumers, the enterprise server market is still the largest source of demand for SSDs. In many cases, SSDs are used in a tiered storage scenario, replacing short-stroked 15k RPM mechanical hard disk drives. Even though SSDs are expensive in terms of cost per gigabyte, they offer the greatest performance return due to their fast access times and read/write rates. Power and cooling requirements are also greatly reduced, a bonus for environmentally conscious companies looking to cut costs.
Due to the heavy transactional workloads required, these enterprise grade SSDs must use Single Level Cell NAND chips. All NAND chips have a limited number of writes per cell, but SLC NAND has ten times the number of writes available versus MLC NAND flash chips. MLC flash typically has around 10,000 write-erase cycles, while SLC flash has around 100,000 write-erase cycles. Wear-leveling algorithms are used to limit the number of writes and manage write-erase cycles. The higher the capacity of the SSD, the more room there is for the algorithms to do their work.
OCZ Technology is leveraging the current design of the Vertex series by swapping out MLC chips for more costly SLC chips in order to target this market specifically. The Vertex EX series will be available in 60GB and 120GB models, with maximum read speeds of 260 MB/s and maximum write speeds of 210 MB/s in the 120GB model. Random read and write speeds are not currently available yet, but are expected to be superior to regular Vertex series SSDs using MLC flash. The firmware has also been tuned for a higher number of IOPS (Input/Output Operations Per Second), since it is a commonly used benchmark in the enterprise market.
Pricing and shipping dates for OCZ's Vertex EX series have not yet been announced, but OCZ will offer a two-year warranty when they ship.
Intel is the current volume and performance leader in the enterprise server and workstation SSD market. However, its most advanced SSD is the X-25E 64GB SLC SSD, with sustained sequential read/write speeds of up to 250/170 MB/s.
Super Talent is the only other SSD manufacturer featuring SLC capacities larger than Intel's. It recently launched the MasterDrive RX Series, with SLC SSD models available in 128GB and 256GB capacities. It offers sustained sequential read/write speeds of up to 230/200 MB/s for SLC models.
quote: Traditional magnetic technology will always beat SSDs in the longevity stakes unless they find a way to eliminate cell wear.