Researchers Challenge NAND Flash with Phase Change Memory

By Michael Feldman

June 6, 2011

A team of researchers at the University of California, San Diego (UCSD) has built a solid state storage system that they claim outperforms state-of-the-art flash memory products. The new system, know as Moneta, uses phase change memory, a technology that some predict will replace the NAND flash memory used in nearly every solid state drive (SSD) today. The UCSD prototype will be on display this week at the Design Automation Conference in San Diego.

Moneta, which is the Latin name for the goddess of memory, uses phase change memory (PCM) module from Micron Technology as the storage medium and employs Xilinx FPGAs as memory controllers. The system DIMM, referred to as Onyx, is a 640 MB device made up of 40 of Micron’s 16 MB PCM (P8P) chips.* The entire system houses 16 of these DIMMs, yielding 10 GB of raw storage: 8 GB usable and 2 GB for error correction and metadata. The card connects to a Linux host via a PCIe x8 link. The prototype and its performance characteristics are described in detail here.

Like NAND flash memory, phase change memory is non-volatile, but it’s a total different digital animal. PCM is based on a metal alloy called chalcogenide and works, as its name suggests, by changing the state of the alloy. To write data, electrical current is applied to generate heat, which switches the alloy between its crystalline and its amorphous state. To read the data back, a smaller current is applied to determine which state the alloy is in.

PCM has several significant advantages over NAND. To begin with, it is inherently more robust than NAND, having an average endurance of 100,000,000 write cycles as compared to 100,000 for enterprise-class SLC NAND. That means the wear leveling algorithm can be much simpler, resulting in less software and memory overhead. PCM is also byte addressable, which means it is much more efficient than NAND at accessing smaller chunks of data, again reducing system complexity. Finally, PCM is just faster. The bits can be switched quickly, and can be flipped in place, avoiding the laborious block erase-and-write cycle required by NAND.

A longer term advantage cited for PCM is that it will scale better than NAND (or even DRAM) as process geometries shrink below 20nm. This has yet to be proven, but it has certainly encouraged companies like Micron and Intel to invest heavily in the technology.

The PCM hardware is only half of the Moneta story though. The system’s real value is contained in the software, which has been tuned for the higher performing PCM. Specifically, they developed a low-level block driver for Moneta that bypasses the Linux I/O scheduler, such that throughput and latency are optimized.

“We’ve found that you can build a much faster storage device, but in order to really make use of it, you have to change the software that manages it as well. Storage systems have evolved over the last 40 years to cater to disks, and disks are very, very slow,” said Steven Swanson, professor of Computer Science and Engineering at UCSD and director of its Non-Volatile Systems Lab (NVSL). “Designing storage systems that can fully leverage technologies like PCM requires rethinking almost every aspect of how a computer system’s software manages and accesses storage. Moneta gives us a window into the future of what computer storage systems are going to look like, and gives us the opportunity now to rethink how we design computer systems in response.”

To prove the technology’s worth, the UCSD team compared Moneta to a well known NAND flash product, in this case, an 80GB Fusion-io ioDrive. However, being a first-generation prototype, the results are somewhat of a mixed bag.

For 512-byte block accesses, Moneta can read data at 327 MB/sec and write at 91 MB/sec; which is between two and seven times faster than the Fusion-io ioDrive. For large data blocks (32K and up), Moneta can read data at 1.1 GB/sec and write data at 371 MB/sec. Here the PCM system is still outrunning the ioDrive for reads, but is actually somewhat slower in writes. The researchers attribute this to the ioDrive’s better aggregate bandwidth associated with its larger memory capacity, all of which is optimized for large block sizes.

Keep in mind that Fusion-io also offers PCIe flash devices with much more capacity and associated bandwidth than the version the UCSD researchers benchmarked. For example, Fusion-io claims 1.5 GB/sec in both reads and writes for its 320 GB ioDrive Duo with 64K block sizes, and 6.0 GB/sec in reads and 4.4 GB/sec in writes for its giant 5TB ioDrive Octal. Obviously size matters.

Other NAND SSD vendors are pushing the capacity/bandwidth envelop as well. Micron’s 700GB P320h flash drive delivers 3 GB/sec for reading and 2 GB/sec for writing (128K blocks); the latest 900GB RamSan-70 card for Texas Memory Systems manages 2 GB/sec reads and 1.4 GB/sec writes; and Virident Systems’ 800GB tachIOn drive tops out at 1.44 GB/sec and 1.2 GB/sec for reads and writes, respectively.

Of course, I/O bandwidth is just a single criteria. Performance under various loads and conditions (like when a drive becomes full) is also important. Cost, latency, longevity, power consumption are other factors that need to be considered.

In the case of power consumption, the UCSD researchers point out that because of the less idiosyncratic behavior of PCM compared to NAND, the software driver is simpler, thus there is a reduction in CPU usage. The researchers say that their Moneta prototype spends between 20 and 50 percent less CPU time performing I/O operations for small requests. That frees up the CPU to do application work and reduces the overall power consumption of the storage system.

The bottom line is that if Moneta can be scaled up to larger memory capacities and aggregate bandwidth on a single PCIe device, its natural advantage in read performance, small (i.e., random) write performance, and endurance will give the NAND-based SSD makers something to think about. The UCSD researchers contend that a PCM-based storage system will be of particular value in applications like high-performance caching systems and key-value stores, that require high performance reads and small writes. For example, applications that do a lot of random I/O, like large graph computations, are especially suited to Moneta-type architectures.

The UCSD team plans to upgrade Moneta in the next six to nine months, using denser and higher performing PCM devices. No PCM roadmap from Micron or anyone else has been made public, but the researchers say that the Moneta technology could be commercially available in just a few years.

*The original version of this story erroneously reported the DIMM and P8P storage specifications in GB rather than MB. –Editor

Subscribe to HPCwire's Weekly Update!

Be the most informed person in the room! Stay ahead of the tech trends with industy updates delivered to you every week!

Google Cloud Makes Good on Promise to Add Nvidia P100 GPUs

September 21, 2017

Google has taken down the notice on its cloud platform website that says Nvidia Tesla P100s are “coming soon.” That's because the search giant has announced the beta launch of the high-end P100 Nvidia Tesla GPUs on t Read more…

By George Leopold

Cray Wins $48M Supercomputer Contract from KISTI

September 21, 2017

It was a good day for Cray which won a $48 million contract from the Korea Institute of Science and Technology Information (KISTI) for a 128-rack CS500 cluster supercomputer. The new system, equipped with Intel Xeon Scal Read more…

By John Russell

Adolfy Hoisie to Lead Brookhaven’s Computing for National Security Effort

September 21, 2017

Brookhaven National Laboratory announced today that Adolfy Hoisie will chair its newly formed Computing for National Security department, which is part of Brookhaven’s new Computational Science Initiative (CSI). Read more…

By John Russell

HPE Extreme Performance Solutions

HPE Prepares Customers for Success with the HPC Software Portfolio

High performance computing (HPC) software is key to harnessing the full power of HPC environments. Development and management tools enable IT departments to streamline installation and maintenance of their systems as well as create, optimize, and run their HPC applications. Read more…

PNNL’s Center for Advanced Tech Evaluation Seeks Wider HPC Community Ties

September 21, 2017

Two years ago the Department of Energy established the Center for Advanced Technology Evaluation (CENATE) at Pacific Northwest National Laboratory (PNNL). CENATE’s ambitious mission was to be a proving ground for near- Read more…

By John Russell

Stanford University and UberCloud Achieve Breakthrough in Living Heart Simulations

September 21, 2017

Cardiac arrhythmia can be an undesirable and potentially lethal side effect of drugs. During this condition, the electrical activity of the heart turns chaotic, Read more…

By Wolfgang Gentzsch, UberCloud, and Francisco Sahli, Stanford University

PNNL’s Center for Advanced Tech Evaluation Seeks Wider HPC Community Ties

September 21, 2017

Two years ago the Department of Energy established the Center for Advanced Technology Evaluation (CENATE) at Pacific Northwest National Laboratory (PNNL). CENAT Read more…

By John Russell

Exascale Computing Project Names Doug Kothe as Director

September 20, 2017

The Department of Energy’s Exascale Computing Project (ECP) has named Doug Kothe as its new director effective October 1. He replaces Paul Messina, who is s Read more…

Takeaways from the Milwaukee HPC User Forum

September 19, 2017

Milwaukee’s elegant Pfister Hotel hosted approximately 100 attendees for the 66th HPC User Forum (September 5-7, 2017). In the original home city of Pabst Blu Read more…

By Merle Giles

Kathy Yelick Charts the Promise and Progress of Exascale Science

September 15, 2017

On Friday, Sept. 8, Kathy Yelick of Lawrence Berkeley National Laboratory and the University of California, Berkeley, delivered the keynote address on “Breakt Read more…

By Tiffany Trader

DARPA Pledges Another $300 Million for Post-Moore’s Readiness

September 14, 2017

The Defense Advanced Research Projects Agency (DARPA) launched a giant funding effort to ensure the United States can sustain the pace of electronic innovation vital to both a flourishing economy and a secure military. Under the banner of the Electronics Resurgence Initiative (ERI), some $500-$800 million will be invested in post-Moore’s Law technologies. Read more…

By Tiffany Trader

IBM Breaks Ground for Complex Quantum Chemistry

September 14, 2017

IBM has reported the use of a novel algorithm to simulate BeH2 (beryllium-hydride) on a quantum computer. This is the largest molecule so far simulated on a quantum computer. The technique, which used six qubits of a seven-qubit system, is an important step forward and may suggest an approach to simulating ever larger molecules. Read more…

By John Russell

Cubes, Culture, and a New Challenge: Trish Damkroger Talks about Life at Intel—and Why HPC Matters More Than Ever

September 13, 2017

Trish Damkroger wasn’t looking to change jobs when she attended SC15 in Austin, Texas. Capping a 15-year career within Department of Energy (DOE) laboratories, she was acting Associate Director for Computation at Lawrence Livermore National Laboratory (LLNL). Her mission was to equip the lab’s scientists and research partners with resources that would advance their cutting-edge work... Read more…

By Jan Rowell

How ‘Knights Mill’ Gets Its Deep Learning Flops

June 22, 2017

Intel, the subject of much speculation regarding the delayed, rewritten or potentially canceled “Aurora” contract (the Argonne Lab part of the CORAL “ Read more…

By Tiffany Trader

Reinders: “AVX-512 May Be a Hidden Gem” in Intel Xeon Scalable Processors

June 29, 2017

Imagine if we could use vector processing on something other than just floating point problems.  Today, GPUs and CPUs work tirelessly to accelerate algorithms Read more…

By James Reinders

NERSC Scales Scientific Deep Learning to 15 Petaflops

August 28, 2017

A collaborative effort between Intel, NERSC and Stanford has delivered the first 15-petaflops deep learning software running on HPC platforms and is, according Read more…

By Rob Farber

Russian Researchers Claim First Quantum-Safe Blockchain

May 25, 2017

The Russian Quantum Center today announced it has overcome the threat of quantum cryptography by creating the first quantum-safe blockchain, securing cryptocurrencies like Bitcoin, along with classified government communications and other sensitive digital transfers. Read more…

By Doug Black

Oracle Layoffs Reportedly Hit SPARC and Solaris Hard

September 7, 2017

Oracle’s latest layoffs have many wondering if this is the end of the line for the SPARC processor and Solaris OS development. As reported by multiple sources Read more…

By John Russell

Six Exascale PathForward Vendors Selected; DoE Providing $258M

June 15, 2017

The much-anticipated PathForward awards for hardware R&D in support of the Exascale Computing Project were announced today with six vendors selected – AMD Read more…

By John Russell

Google Debuts TPU v2 and will Add to Google Cloud

May 25, 2017

Not long after stirring attention in the deep learning/AI community by revealing the details of its Tensor Processing Unit (TPU), Google last week announced the Read more…

By John Russell

Top500 Results: Latest List Trends and What’s in Store

June 19, 2017

Greetings from Frankfurt and the 2017 International Supercomputing Conference where the latest Top500 list has just been revealed. Although there were no major Read more…

By Tiffany Trader

Leading Solution Providers

IBM Clears Path to 5nm with Silicon Nanosheets

June 5, 2017

Two years since announcing the industry’s first 7nm node test chip, IBM and its research alliance partners GlobalFoundries and Samsung have developed a proces Read more…

By Tiffany Trader

Nvidia Responds to Google TPU Benchmarking

April 10, 2017

Nvidia highlights strengths of its newest GPU silicon in response to Google's report on the performance and energy advantages of its custom tensor processor. Read more…

By Tiffany Trader

Graphcore Readies Launch of 16nm Colossus-IPU Chip

July 20, 2017

A second $30 million funding round for U.K. AI chip developer Graphcore sets up the company to go to market with its “intelligent processing unit” (IPU) in Read more…

By Tiffany Trader

Google Releases Deeplearn.js to Further Democratize Machine Learning

August 17, 2017

Spreading the use of machine learning tools is one of the goals of Google’s PAIR (People + AI Research) initiative, which was introduced in early July. Last w Read more…

By John Russell

EU Funds 20 Million Euro ARM+FPGA Exascale Project

September 7, 2017

At the Barcelona Supercomputer Centre on Wednesday (Sept. 6), 16 partners gathered to launch the EuroEXA project, which invests €20 million over three-and-a-half years into exascale-focused research and development. Led by the Horizon 2020 program, EuroEXA picks up the banner of a triad of partner projects — ExaNeSt, EcoScale and ExaNoDe — building on their work... Read more…

By Tiffany Trader

Amazon Debuts New AMD-based GPU Instances for Graphics Acceleration

September 12, 2017

Last week Amazon Web Services (AWS) streaming service, AppStream 2.0, introduced a new GPU instance called Graphics Design intended to accelerate graphics. The Read more…

By John Russell

Cray Moves to Acquire the Seagate ClusterStor Line

July 28, 2017

This week Cray announced that it is picking up Seagate's ClusterStor HPC storage array business for an undisclosed sum. "In short we're effectively transitioning the bulk of the ClusterStor product line to Cray," said CEO Peter Ungaro. Read more…

By Tiffany Trader

IBM Advances Web-based Quantum Programming

September 5, 2017

IBM Research is pairing its Jupyter-based Data Science Experience notebook environment with its cloud-based quantum computer, IBM Q, in hopes of encouraging a new class of entrepreneurial user to solve intractable problems that even exceed the capabilities of the best AI systems. Read more…

By Alex Woodie

  • arrow
  • Click Here for More Headlines
  • arrow
Share This