I’ve been meaning to write about a comment regarding NAND Flash memory and SSDs written by Thomas McCormick in LinkedIn’s Solid State Storage Group and this seems like the perfect time. McCormick is an Integrated Hardware/Software Product Development Leader at ECI Innovations, a custom instrumentation and control systems design house in Chelmsford, MA. McCormick was responding to a blog post written by Greg Schulz (“Researchers and marketers don’t agree on future of NAND flash SSD”) who founded Storageio and whose blog is located at storageioblog.com. In the post in question, Schulz discussed the famous/infamous UCSD report on the bleak future of NAND Flash memory. (For even more details, see my discussion of that report at “The sky is falling! The sky is falling! Paper predicts the bleak future of SSDs and NAND Flash memory”)
Essentially, the UCSD paper concluded that NAND Flash memory optimized for simpler applications such as USB memory drives and SD cards emphasizes cost/bit over durability, reliability, and retention time, thus making such NAND Flash memory increasingly unattractive for use in SSDs, which need to emphasize the attributes that aren’t presently valued.
In his comment to the Schulz blog post, McCormick wrote:
“I think that there is little doubt that NAND flash market has been predominantly chasing $/GB. All other parameters such as endurance, performance, retention, BER appear to be secondary concerns as they have been degrading rapidly with recent NAND process technologies (both shrink and increasing bits per cell).
Flash memory system designers serving markets other than consumer (such as enterprise and embedded) need to be concerned with these diminishing parameters and design flash memory systems that make accommodates for these new parameters. Researchers can point out the flaws, but researchers can also develop solutions as can flash system designers in industry. There is always another replacement technology for NAND just around the corner, but the present is NAND and researchers and industry need to work together to ensure that the needs of the markets are met.”
When I wrote about the UCSD report, I discussed alternative storage media such as MRAM and Memristors, which both aspire to the non-volatile memory crown currently worn by NAND Flash memory. But McCormick’s comment suggested yet another alternative, which is why I’ve returned to this topic.
It’s entirely possible for the NAND Flash industry to niche itself the way that the DRAM market has become niched. For DRAMs, we now have part families optimized for PCs and Servers (DDR), for mobile applications (LPDDR), and for graphics (GDDR). If SSDs get big enough—and there’s no reason to doubt that they will if they haven’t already done so—then there’s a possibility that a new niche for NAND Flash memory could arise with somewhat different optimizations than those employed for the USB memory stick and SD card markets. In fact, the promises of improved durability and reliability of 3D NAND Flash memory might well be first realized in parts optimized for SSD applications.
Denali Memory Report 