PCM-based Storage – A Game Changer?
It looks like the ubiquitous NAND Flash memory is about to get some serious competition in the near future from Phase Change Memory (PCM), according to researchers from the University of California, San Diego (UCSD). They have built PCIe SSD prototypes called Moneta and Onyx based on PCM modules that delivers truly astonishing performance compared to the fastest NAND-based SSDs available today.
Moreover, they promise greatly improved durability, even compared to enterprise-class SLC NAND. Phase-Change Memory, like NAND, only lasts for so many write cycles, but PCM drives are vastly more robust than anything currently on the market. They will allegedly last for about 100,000,000 write cycles compared to 100,000 in today’s best enterprise SLC NAND (or approximately 3,000 write cycles in a current consumer-level 25nm MLC drive). If that’s not enough, PCM drives need less CPU and RAM (i.e. software) overhead to do the same thing as NAND SSDs, only much faster.
The Moneta array (emulated PCM) reaches a sustained bandwidth of 2.8GB/s and 541,000 random 4K IOPS, and 1.1M 512-byte IOPS. The teams Onyx prototype uses 1st generation Phase-Change Memory and produces 1.1GB/s for reads, but plans are underway to make it both faster and denser.
PCM is non-volatile just like NAND Flash, but work in an entirely different way. The technology uses the metal alloy chalcogenide to store data, and as the name implies the drives use a current to switch the alloy between the two states amorphous or crystalline. Although these drives are still at the development stage, the results so far look very promising and in a few years time this technology will no doubt be much faster as well as considerably more durable than conventional NAND.