SAN JOSE, Calif. — The Storage Networking Industry Association (SNIA) has created a special interest group to foster the adoption of nonvolatile DIMM (NVDIMM), which it sees as the early days of computing architectures that combine storage and memory as a single entity.
Launched during the SNIA Annual Members' Symposium late last month, the NVDIMM SIG is an open community under the umbrella of its Solid State Storage Initiative. Initial participating members include Intel, Micron, Microsoft, Samsung, SK Hynix, SMART Modular Technologies, Viking Technology, AgigA Tech, IDT, Inphi, Netlist, and Pericom.
NVDIMMs are persistent memory modules that reside on the DDR DRAM channel, combining volatile DRAM memory and nonvolatile flash memory. Under normal power conditions, an NVDIMM operates exactly like a regular DRAM module. During a power failure or system crash, it is powered by a supercapacitor pack. The data within the DRAM is transferred to the flash and can be restored to the DRAM when normal conditions resume.
Persistent memory enables applications to run at higher speeds with improved I/O performance, including databases in environments that can't afford downtime, such as online transaction processing and financial services, which could benefit from the fast rebuild times offered by integrated NVDIMMs.
NV DIMM products are already on the market. AgigA's AGIGARAM NVDIMM combines standard DRAM with NAND flash and an ultracapacitor power source. Under normal operation, AGIGARAM provides all the capabilities of high-speed DRAM, but in the event of power loss, the ultracapacitor provides a burst of electricity used to write main memory contents to the NAND flash chip, where it can be held indefinitely. The AGIGARAM NVDIMM restores data from NAND flash to DRAM upon system recovery.
NVDIMMs meet the mechanical dimensions defined by the JEDEC MO-269 specifications for a DDR3 DIMM module, but they also have a cable to the supercapacitor power pack and require an NVDIMM-enabled server, including BIOS awareness. Part of the NVDIMM SIG's mandate is to educate system vendors on incorporating NVDIMMs into their servers and platforms and to communicate industry standards to foster NVDIMM adoption and evolution in the ecosystem.
Viking's Adrian Proctor, acting chairman of the NVDIMM SIG, told us NVDIMM can address the endurance challenges faced by SSDs. His company's ArxCis NVDIMM can be slotted into servers and RAID controllers as an alternative for battery backed-up memory modules. The devices can use supercapacitors to write to NAND flash. They can also be paired with SSDs to extend their life and performance.
SSDs are much faster than spinning disks, Proctor said, but they are much slower than DDR memory. In addition, DDR memory doesn't have flash memory's limited number of writes; endurance is flash memory's Achilles heel. A great deal of investment is being put into memory technology development, but it's going to be at least a decade before the next generation of memory is widely available with an ecosystem to support it.
Viking's Arx-Cis-NV DDR3 nonvolatile DIMM.
At the very least, said Proctor, an economically viable replacement for DRAM, whether it is MRAM or something else, is not going to be on the market within the next three years, so merging mainstream memory technologies such as DRAM and flash today in the form of NVDIMM allows applications to treat memory as persistent and improve performance.
Intel's Jim Pappas, also an early member of the SIG, said NVDIMM adoption is laying the early groundwork for a fundamental change in computing architectures. As NAND flash is supplemented over the next few years by new technologies with improved durability and the same performance as system memory, "we'll be able to start thinking about building systems where memory and storage are combined into one entity," he said. "This is the megachange to computer architecture that SNIA is looking at now and preparing the industry for when these new technologies happen."