Phase change memory-based 'moneta' system points to the future of computer storage

Jun 02, 2011
This is a view of the internals of the Moneta storage array with phase change memory modules installed. Credit: UC San Diego / Steve Swanson

A University of California, San Diego faculty-student team is about to demonstrate a first-of-its kind, phase-change memory solid state storage device that provides performance thousands of times faster than a conventional hard drive and up to seven times faster than current state-of-the-art solid-state drives (SSDs).

The device was developed in the Computer Science and Engineering department at the UC San Diego Jacobs School of Engineering and will be on exhibit June 7-8 at DAC 2011, the world's leading technical conference and trade show on electronic design automation, with the support of several industry partners, including Micron Technology, BEEcube and Xilinx. The , called "Moneta," uses phase-change memory (PCM), an emerging data technology that stores data in the of a metal alloy called a chalcogenide. PCM is faster and simpler to use than flash memory – the technology that currently dominates the SSD market.

Moneta marks the latest advancement in solid state drives (SSDs). Unlike conventional hard disk drives, solid state storage drives have no moving parts. Today's SSDs use flash memory and can be found in a wide range of consumer electronics such as iPads and laptops. Although faster than hard disk, is still too slow to meet modern data storage and analysis demands, particularly in the area of high performance computing where the ability to sift through enormous volumes of data quickly is critical. Examples include storing and analyzing scientific data collected through environmental sensors, or even web searches through Google.

"As a society, we can gather all this data very, very quickly – much faster than we can analyze it with conventional, disk-based storage systems," said Steven Swanson, professor of Computer Science and Engineering and director of the Non-Volatile Systems Lab (NVSL). "Phase-change memory-based solid state storage devices will allow us to sift through all of this data, make sense of it, and extract useful information much faster. It has the potential to be revolutionary."

PCM Memory Chips

To store data, the PCM memory chips switch the alloy between a crystalline and amorphous state based on the application of heat through an electrical current. To read the data, the chips use a smaller current to determine which state the chalcogenide is in.

Moneta uses Micron Technology's first-generation PCM chips and can read large sections of data at a maximum rate of 1.1 gigabytes per second and write data at up to 371 megabytes per second. For smaller accesses (e.g., 512 B), Moneta can read at 327 megabytes per second and write at 91 megabytes per second , or between two and seven times faster than a state-of-the-art, flash-based SSD. Moneta also provides lower latency for each operation and should reduce energy requirements for data-intensive applications.

A Glimpse at Computers of the Future

Swanson hopes to build the second generation of the Moneta in the next six to nine months and says the technology could be ready for market in just a few years as the underlying technology improves. The development has also revealed a new technology challenge.

"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 Swanson. "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."

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User comments : 6

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plasma_guy
not rated yet Jun 02, 2011
PCM SSD has even harder time to compete cost per bit against HDD, compared to conventional SSD. Speed is not key to storage, retention is.
Eric_B
5 / 5 (1) Jun 02, 2011
were retention and durability issues mentioned in this article?
SemiNerd
3.7 / 5 (3) Jun 02, 2011
were retention and durability issues mentioned in this article?

I certainly didn't see these absolutely key issues addressed, although the fact that the memory is retained as a material phase change makes it inherently more stable than a device that stores charges. Still it should have been mentioned.

In addition, for really large POM SSD, the costs per bit have to come down vs flash quite substantially. Its hard to see how that can happen given the huge technological lead time that Flash has.

It looks like the inherent complexity of the POM cell is roughly the same as a Flash cell. Its hard to imagine that POM can ever be made significantly cheaper or smaller. There may be inherent power demand advantages, but I also didn't see that as an inherent advantage.
jas99
5 / 5 (2) Jun 02, 2011
Having read about this type of memory previously, it was stated that retention and durability were apparently and practically infinite: no loss of retention and no perceived lifespan issues. The physical process used is infinitely repeatable.
ecdfan
1.7 / 5 (6) Jun 02, 2011
The UCSD faculty-student team are simply a bunch of fraudsters, I am sorry to say. Fusion-io's Flash SSDs read and write at 1.5 gigabytes per second. That is far better than Moneta's 1.1 gigabytes per second read and 371 megabytes per second read. PCM sucks because of costs, durability, and performance. It is a scam and will never be commercialized in volume.
Eikka
not rated yet Jun 03, 2011
Thing is, you can make all sorts of memory devices fast by having them in parallel and spreading the load. The 1.1 GBps figure tells us nothing.

The 371/91 MBps figure for small data transfers does. It is at par with Flash drives that currently perform around 225/110 MBps. Slightly faster at reading, slightly slower at writing.

The device is not 2x faster than state of the art Flash drives. More like 3/2 faster if at all.

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