Virtually every storage analyst and editor (including me) put solid-state disk (SSD) drives on their Top Technologies of 2009 list, despite miniscule unit shipments. Although you could argue that reliability concerns are a gating factor to widespread adoption of SSDs, the real gating factor is the same as it's always been — high cost. That may be changing.
A number of enterprise-class SSD vendors have added multi-level cell (MLC) SSDs to their existing line of single-level cell (SLC) SSDs. As discussed in "Does MLC flash belong in enterprise SSDs?" by Objective Analysis SSD analyst and director Jim Handy, the price differences between SLC and relatively low-cost MLC flash are significant.
SLC-based SSDs will probably always have a place at the high end of the SSD spectrum because of inherent durability and performance advantages (check out the stats on Texas Memory's SLC-based RamSan-6200 system — five million IOPS), but the trend is toward MLC enterprise SSDs. This is because a variety of vendors have figured out innovative ways to use software and controller technologies to mitigate the performance/endurance differences between MLC and SLC. See Jim's article on page X for an in-depth discussion of this trend.
In a recent newsletter, Storage Strategies Now senior analyst James E. Bagley noted that MLC client (non-enterprise) SSD drives are now priced at less than $6 per GB and enterprise-class MLC drives are headed for the <$10-per-GB range in volume quantities by the end of the year — not in the ballpark of traditional hard disk drives, but the trend is encouraging.
In addition to the move toward MLC flash, Bagley highlights a few more trends in the SSD space this year, including SAS-based MLC enterprise SSDs and new file management strategies that more effectively integrate SSDs in storage arrays (examples: EMC's FAST and Sun's ZFS, with more to come).