The narrative in storage circles these days revolves largely around Flash vs. disk. But whether you think spinning disks actually have a future in the enterprise or not, an even bigger battle may be brewing for emerging data infrastructure: Flash vs. RAM.
With emerging storage infrastructure gravitating toward in-memory solutions for Big Data and real-time analytics, it makes sense that the enterprise would want to employ the most effective means of data access and retrieval. And with new forms of non-volatile RAM on the drawing board, system architects will find that their storage options are not as cut-and-dried as they seem.
If it was just a question of speed, solutions like DRAM would win hands down. But raw performance does not always tell the entire story, as recent experiments at MIT suggest. When researchers put the two solutions up against each other in a working HPC environment that included spinning disks, the performance penalty for RAM turned out to be much higher than on a properly configured Flash array depending on how often the application had to pull data from the hard disk. According to their results, if disk retrieval exceeds 5 percent, you’re better off with a 20TB NAND Flash configuration than 10TB of DRAM, and you’ll draw far less power as well.
The trouble with Flash, though, is that it is already pushing up against its practical limits while RAM still has a number of development paths on the table, says Crossbar co-founder Dr. Wei D. Lu. The company is a leading proponent of resistive RAM (RRAM) that promises to deliver upwards of 1TB storage-on-chip solutions that could affect everything from cell phones to mainframes. Lu claims the company’s 1T1R and 1TnR solutions also provide lower latency; improved write throughput; and better endurance, retention and density than Flash, and can be licensed at less cost. Initial applications include stand-alone memory chips and non-volatile IP blocks for MCUs, SoCs and FPGAs.
Meanwhile, backers of Magnetoresistive RAM (MRAM) are hoping the technology will emerge from its niche corners in embedded industrial systems and into more mainstream data applications. Everspin Technologies recently inked a deal with Koyo Electronics to implement its Direct Logic 205 (DL205) programmable logic controller (PLC) for its factory automation systems, but Everspin executives say they are actively looking for data center, cloud and other uses that would benefit from improved data persistence, integrity and latency. A key application would be as a metadata and storage system data store for a RAID array. As a non-volatile memory solution, MRAM would enable faster rebuilds of the storage environment in the event of a power outage.
Even mainstream hardware developers are moving toward RAM for emerging modular platforms. James Niccolai at IDG says HP’s Machine will be ready to ship to development partners within the year even though the “memristor” technology that will eventually populate the system will not be ready. Instead, the company will use standard DRAM to provide up to 320TB of main memory for more than 2,500 cores. The company chose DRAM over NAND Flash because its performance characteristics should more closely match the memristor solution, although the company admits it comes with a higher energy draw. By the time production models hit the channel roughly 10 years from now, HP expects the prototype to evolve from DRAM to phase-change memory and finally to memristor, all of which will support the basic Memory-Driven Computing architecture that places memory as the central component surrounded by multiple CPUs.
It seems that even in the modular world there will still be crucial questions to answer regarding architecture and underlying technologies, and these are likely to be answered only by taking workloads, applications and other factors into consideration.
And while emerging forms of non-volatile RAM are likely to be the speediest solutions on the market, they will not necessarily become the go-to storage solution by default.
Arthur Cole writes about infrastructure for IT Business Edge. Cole has been covering the high-tech media and computing industries for more than 20 years, having served as editor of TV Technology, Video Technology News, Internet News and Multimedia Weekly. His contributions have appeared in Communications Today and Enterprise Networking Planet and as web content for numerous high-tech clients like TwinStrata, Carpathia and NetMagic.