Beginning early 2010, Netlist will offer a new RDIMM technology that will double the per-CPU memory capacity to 384GB while costing far less than double the spot price of RAM. Netlist was demonstrating the new 16GB DDR3 RDIMM parts at the Supercomputing 09 conference last week in Oregon. Samples are due next month, and it ships in production quantities in the first quarter of 2010.
Dubbed HyperCloud, the new RDIMMs employ proprietary logic that appears to the CPU as the maximum two physical ranks of memory but actually contains four. This "virtual ranking" allows dual socket servers to be populated with as many as 24 of the company's 16GB RDIMMs, for a total capacity of 384GB. According to Paul Duran, director of business development for Netlist, "Those four ranks now look like two ranks to the memory controller. So we can populate four physical ranks or eight virtual ranks per channel." HyperCloud Memory will be available in 4GB, 8GB and 16GB models.
In addition to capacity gains, Duran said that vRank also pays a performance dividend. "The CPU is tricked into thinking it has a single load, therefore it will run at 1,333 [million transfers per second] when you have four DIMMs populated per channel." In today's systems, the CPU supports 1333 MT/s only when populated with one DIMM per channel, he said. With two, it decreases to 1067 MT/s and with three it drops to 800. For systems that are maxed out "that means poor application performance in memory-intensive applications."
Netlist claims that HyperCloud RDIMMs require no bios changes and are interoperable with standard JEDEC RDIMMs, even when they are installed on the same channel. "They are essentially plug-and-play with the JEDEC standard with no issues," Duran said. The trickery is accomplished with two ASICs plus a register device with rank multiplication logic inside. Isolation circuits between each DRAM and the bus connector provide the load reduction.
What's to stop people from viewing HyperCloud as some substandard flash-in-the-pan? "Sure there's skepticism out there, but the skepticism goes away when [people] see that you can plug our DIMM in any standard server and it will work. There's nothing special required. It's all within the chip and plugs into any standard server off the shelf." As for the price, "we have to buy the same DRAM as everybody else, but we believe we can charge a 20 percent premium for this technology." Exact prices were not disclosed.