The performance gap between HDDs and SSDs will shrink
By
Lucas Mearian
February 16, 2012 12:54 PM ET
Computerworld - SAN JOSE -- As the circuitry of NAND flash-based, solid-state drives shrinks, performance drops precipitously -- meaning the technology could be doomed, according to new research.
Speaking to about 500 attendees at the 10th Usenix Conference on File and Storage Technologies here this week, Laura Grupp, a graduate student at the University of California, San Diego, said that as NAND flash densities increase, so do issues such as read and write latency and data errors.
While the density of SSDs grows and the cost per gigabyte shrinks, "everything else about them is poised to get worse," Grupp said.
"This makes the future of SSDs cloudy: While the growing capacity of SSDs and high IOP rates will make them attractive for many applications, the reduction in performance that is necessary to increase capacity while keeping costs in check may make it difficult for SSDs to scale as a viable technology for some applications," Grupp, lead author of
the study, wrote in a research paper.
Grupp, along with Steven Swanson, director of UCSD's Non-Volatile Systems Laboratory, and John Davis of
Microsoft Research, tested 45 different NAND flash chips that ranged in size from 72 nanometer (nm) circuitry to today's 25nm technology. The chips came from six vendors.
The tests revealed that the program speed (write speed) for pages in a flash block suffered dramatic and predictable variations in latency. And, as the NAND flash wore out, error rates also varied widely between devices. Single-level cell (SLC) NAND held up the best in the tests, while multi-level cell (MLC), and in particular, triple-level cell (TLC) NAND, produced the worst results.
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