Optane

Extending the Write/Erase Lifetime of Phase Change Memory: Part 1- PCM Element Separation and Endurance

Ron NealeThis is the first of a new line-up of Memory Guy posts by Ron Neale.   In this 4-part series Ron takes a look at the recently-published analysis by a team from IBM and Yale University (Wiley: Communications of Advanced Materials, Volume 30, Issue 9, March 1, 2018 “Self-Healing of a Confined Phase Change Memory Device with a Metallic Surfactant Layer,” Xie et al) which has cast some new light on the complexity of the movement and element separation in phase change memory (PCM) device structures.


In this series of articles I will briefly review what I think is an important piece of work and its implications for the future of  PCM write/erase (w/e) endurance in commercial PCM memory arrays. Today’s production Phase-Change Memory, the basis of the Intel/Micron 3D XPoint Memory, wears out faster than expected.  This series will investigate some of the potential reasons for this discrepancy.

Back in 2016 a research team led by IBM claimed the world record for PCM w/e endurance of  greater than 2 x 10E12 cycles (ALD-based Confined PCM with a Metallic Liner Toward Unlimited Endurance, Proc IEDM 2016 ). As of today commercially available PCM memory arrays offer w/e endurance of some six orders of magnitude less.  The table below Continue reading

Latest White Paper: New Memories for Efficient Computing

A Potpourri of Emerging MemoriesThere has been a lot of discussion in the trade press lately about new memory technologies.  This is with good reason: Existing memory technologies are approaching a limit after which bits can’t be shrunk any smaller, and that limit would put an end to Moore’s Law.

But there are even more compelling reasons for certain applications to convert from today’s leading technologies (like NAND flash, DRAM, NOR flash, SRAM, and EEPROM) to one of these new technologies, and that is the fact that the newer technologies all provide considerable energy savings in computing environments.

Objective Analysis has just published a white paper that can be downloaded for free which addresses a number of these technologies.  The white paper explains why energy is wasted with today’s technologies and how these new memory types can dramatically reduce energy consumption.

It also provides a Continue reading

Micron’s Super-Fast New 32GB NVDIMM

 

Switch TrackMicron Technology has introduced a 32GB NVDIMM-N.  Perhaps the most important thing about this device is not so much its high density as the fact that it runs at higher bus speeds than competing NVDIMMs, doing 2933 megatransfers per second (MT/s), a speed that Micron representatives tell us is required to support Intel’s Skylake processor.

Up to this point NVDIMM-Ns have been limited to 2400 MT/s, which is fast enough for Broadwell, but which misses the mark for Skylake.  Design is tricky even at this slower speed, requiring a number of expensive high-speed multiplexers in the DRAM’s critical speed path.

“Multiplexers?”  Yes, NVDIMMs use them, even though no other kind of DIMM does.  The Memory Guy can explain why, having just finished a report covering the NVDIMM market and technology.

Here’s a little refresher for those who either don’t remember or never knew that NVDIMM-N requires multiplexers.  The NVDIMM-N looks to the system like a standard Continue reading

Examining 3D XPoint’s 1,000 Times Endurance Benefit

3D XPoint Endurance GraphicThe Memory Guy, as a regular reader of The SSD Guy’s posts, found an interesting one that compares the endurance of Optane SSDs against that of NAND flash SSDs.  Perhaps this could provide some insight into the Intel & Micron claim that 3D XPoint Memory’s endurance is 1,000 times that of standard NAND flash, shown in the graphic to the left.

The SSD Guy post converts several different measures of SSD endurance against each other: TBW, DWPD, and GB/Day.  Definitions of these terms can be found in that post.

It occurred to me that any of these can be used to roughly gauge the relative endurance of 3D XPoint Memory against that of NAND flash.

Take DWPD for example: Drive Writes per Day.  Not only is this a measure of how many times that an SSD can be over-written every day, but it’s also an indication of the number of times that each memory cell can be overwritten.  If you know this, and if you know how long Continue reading