Using Non-Volatile Memory to Save Energy in Servers

Recent breakthroughs in circuit and process technology have enabled new usage models for non-volatile memory technologies such as Flash and phase change RAM (PCRAM) in the general purpose computing environment. These technologies display high density and low power consumption as well as persistency that are appealing properties in a memory device. This paper summarizes our earlier work on improving NAND Flash based disk caches and extends it to consider PCRAM. We first present the primary challenges in reliably managing non-volatile memories such as NAND Flash, reviewing our past work on architectural support for Flash manageability. We then provide a preliminary analysis of how our current Flash manageability architecture may be simplified when we replace Flash with PCRAM. Our evaluations on PCRAM shows a potential for more than a 65% throughput improvement for a disk-intensive database workload. Although more detailed studies are needed, we conclude that PCRAM is a strong contender to replace Flash if it becomes cost-effective.