July 1, 2011

IBM Achieves Computer Memory Breakthrough

IBM has made a phase-change memory (PCM) breakthrough that may lead to the development of solid-state chips (SSD) that will match and surpass NAND flash technology data storage by 100 times the performance and with a greater lifespan, reports Computerworld.

PCM chips created by IBM are able to store two bits of data per cell, and all this without data corruption problems, says IBM.

NAND flash memory, which is currently used in SSD drives, has write rates as high as 2Gbit/sec, says Computerworld. They are widely used as a storage medium in many consumer devices from cell phones to laptops such as the MacBook Air.

Even though NAND flash technology has big advantages over hard drives because they are fast and are nonvolatile, it is limited in lifespan. With a lifespan ranging from 5,000 to 10,000 write cycles in consumer products and up to about 100,000 cycles for enterprise-class products, NAND flash technology can wear out over time. Its erase-write cycle slows NAND's performance down by requiring existing data be marked for deletion before any new data is written to it.

Meanwhile, phase-change media lasts up to 5 million write cycles, IBM says.

"If you can write a flash 3,000 times, that will outlive most cell phones and MP3 players, but that's certainly not good enough for the enterprise that does that in an hour," says Christopher Sciacca, manager of communications for IBM Research in Zurich.

PCM has been around for some time, with uses in devices like CD media, but the technology "relies on the storage material to shift from a crystalline state to an amorphous one when a voltage is applied, which corresponds to the encoding of digital ones and zeroes," according to PCMag.com.

Encoding this way causes the resistance to have a tendency to "drift" over time, in two different ways, making it hard to take into account, says PCMag.com.

IBM found that "even though the drift is random within the crystals themselves, if moves in the same general direction, so it's possible to compensate for it."

Haris Pozidis, manager of memory and probe technologies at IBM research said in a press release that teams of IBM scientists have been testing a multi-level cell (MLC) chip for the past five months. The chip is capable of storing two and eventually three bits of data, which translates into the possibility that it can reach a level of reliability that is suitable for practical application.

"As organizations and consumers increasingly embrace cloud-computing models and services, ever more powerful and efficient, yet affordable storage technologies are needed," Pozidis says.

"By demonstrating a multi-bit phase-change memory technology which achieves for the first time reliability levels akin to those required for enterprise applications, we made a big step towards enabling practical memory devices based on multi-bit PCM."

IBM estimates that the technology will be available commercially in about five years. The company is not planning to produce consumer grade products directly, but instead Pozidis says that IBM's main goal is to license the technology to memory manufacturers like Toshiba and Samsung and help them accelerate the production of the memory chips for enterprise applications.

PCMag.com says that, "if businesses were to replace their inefficient hard-disk-based systems with PCM drives, there could be significant power savings, along with improved performance."


Image Caption: A Drift-tolerant coding demonstration by IBM Researchers in Zurich demonstrated the first large-scale demonstration of multi-level cell state retention in phase-change memory. Photo Michael Lowry


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