This video presentation gives an introduction to 3D XPoint, Intel’s next-generation non-volatile memory (NVM) technology, developed by Intel and Micron. The presenter, Rick Coulson, senior fellow at Intel and leader of the Intel NVM Solutions Group, has more than 30 years of experience in storage and memory technologies. The 3D XPoint technology is Intel’s answer to the challenge that the widening gap between central processing unit (CPU) and storage performance creates for increasing the system performance. The video covers three main topics: a review of the evolution of performance of storage technologies; an overview of the 3D XPoint technology; and an analysis of the instantiations of the technology on computing platforms.

The first part of the presentation discusses the improvement in storage performance over the last 60 years. From 1956 to 2016, the processor clock speed has improved about 40,000,000 times, from 100 Hz to 4 GHz, while the hard disk drive (HDD) storage latency has improved only 100 times, from 600 ms to 6 ms for mainstream HDDs, which represents a 400,000 times slower improvement. Until 2016, the gap between processor and storage performance has been filled using solid state drives (SSDs) such as NAND SSDs. Enterprise class NAND SSDs using the NVMexpress (NVMe) interface provide latencies of less than 100 microseconds and up to 500,000 input/output operations per second (IOPS). NAND SSDs provide an improvement factor of 10,000 of the access time over HDDs, but that is still 4000 less than the improvement in processor clock speed.

The second part of the presentation introduces the 3D XPoint technology. The 3D XPoint technology, announced by Intel in 2015, is the next generation of NVM, providing 1000 times smaller latency than NAND SSD (less than 100 ns), 1000 times the durability of NAND SSD, and 10 times the density of dynamic random-access memory (DRAM). The presentation includes a video clip that gives an overview of the process of creating a 3D XPoint NVM structure: (1) slice submicroscopic layers of material into columns, each containing one memory cell and one selector; (2) connect the columns using a crosspoint structure consisting of perpendicular wires (word wires and bit wires), which enable memory cells to be individually addressed; (3) stack the memory grids created at point (2), yielding a high-density 3D structure, the 3D XPoint; and (4) each memory cell is written to or read by varying the voltage sent. The 3D XPoint design provides a transistor-less, scalable, high-performance memory medium.

The third part of the presentation describes the two instantiations of 3D XPoint in a system: as block storage, and as persistent memory. As block storage, 3D XPoint is a super-fast SSD, marketed under the brand name of Intel Optane, and packaged as a PCIe/NVMe device that provides 10 microsecond latency and up to 500,000 IOPS. The 10 microsecond latency of Intel Optane is 10 times smaller than that of the best current NAND SSD, but it is still far from the potential of 3D XPoint, which can reach a latency under 100 ns. Most of the latency occurring is attributed to the software stack of block storage, which becomes a performance bottleneck. 3D XPoint shows its full potential when used as persistent memory. In this second instantiation, 3D XPoint is packaged like DRAM system memory, using dual in-line memory modules (DIMMs), and is accessed through DDR4-compatible memory channels.

Persistent memory has two main use cases: as a large system memory, and as a persistent memory-aware file system. In the first case, 3D XPoint is used as high-capacity system memory, with the DRAM becoming the cache for the persistent memory. System memory based on 3D XPoint can reach up to four times the capacity of DRAM-based memory at a lower cost than DRAM and without modifications to the operations system or applications. Using 3D XPoint as system memory requires support from the processor; the next generation of Intel Xeon processors will provide support for 3D XPoint-based DIMMs. In the second case, 3D XPoint is explicitly managed as persistent memory, using the SNIA-approved open NVM programming model, which includes interfaces such as persistent memory aware file systems, standard file application programming interface (API), and load/store. In conclusion, 3D XPoint is a novel, fast, dense, non-volatile, inexpensive memory technology that can be used either as block storage (ultra-fast SSD), as a high-capacity system memory, or as a new type of persistent memory.

This presentation is worth watching by all those interested in the emergence of storage class memory.