In a terrific demo of the wrong technology for the Flash Memory Summit, HGST is showing a PCIe-connected Phase Change Memory device running at three million IOPS with a 1.5 microsecs read latency.
For a very long time I’ve been keenly following the IOPs ratings of newly announced flash memory devices. From the SATA->SSD generation and the most recent PCIe generation to the UltraDIMMs. Now however, this Phase Change Memory announcement has kind of pushed all those other technologies aside. While the IOPs are far above a lot of other competing technologies, that is for reads and not writes. The speed/latency of the writes is about 55 times slower than the reads. So if you want top speed on reading and not writing the data, PCM is your best choice. But 55 times slower is not bad, it puts the write speed at approximately the same speed as Multi-Level Cell (MLC) flash memory currently used in your consumer grade SSD flash drives.
Chris Mellor’s emphasis is PCM likely better suited as a competitor to UltraDIMM as a motherboard memory than a faster PCIe SSD drive. And a lot depends on the chips, glue logic and Application Specific Integrated Circuits (ASICs) on the PCIe board. HGST went to great lengths to juice the whole project by creating a bypass around the typical PCIe interfaces allowing much greater throughput overall. Without that engineering trick, it’s likely the 3M IOPs level wouldn’t have been as easily achieved. So bear in mind, this is nowhere near being a shipping product. In order to achieve that level of development it’s going to take more time to make the thing work using a commodity PCIe chipset on a commodity designed/built motherboard. But still 3M IOPs is pretty impressive.