Energy-Efficient Streaming Using Non-Volatile Memory


Dr. Mohammed G. Khatib (University of Twente, NL)


The disk and the DRAM in a typical mobile system consume a significant fraction (up to 30%) of the total system energy. To save on storage energy, the DRAM should be small and the disk should be spun down for long periods of time. We show that this can be achieved for predominantly streaming workloads by connecting the disk to the DRAM via a large non-volatile memory (NVM). We refer to this as the NVM-based architecture (NVMBA); the conventional architecture with only a DRAM and a disk is referred to as DRAMBA. The NVM in the NVMBA acts as a traffic reshaper from the disk to the DRAM. If the cost increase due to adding the NVM is compensated by the decrease in DRAM cost, the total system cost may remain the same.

We analyze the energy saving of NVMBA, with flash serving as NVM, relative to DRAMBA with respect to (1) the streaming demand, (2) the disk form factor, (3) the best-effort percentage, and (4) the stream position on the disk. We present a worst-case analysis of the reliability of the disk drive and the flash memory and show that a small flash capacity is sufficient to operate the system over a year at negligible cost. Disk lifetime is superior to flash, so that it is not a concern.


Mohammed G. Khatib is a postdoctoral researcher at the University of Twente in the Netherlands. He received his MSc degree in Computer Science from the Technical University of Braunschweig in Germany in 2004 and the PhD degree in Computer Science from the University of Twente in 2009. Dr. Khatib's research interests revolve around Green Computing. He investigates energy-efficient computer architecture and storage systems. He was a visiting scholar at the SSRC center at the University of California at Santa Cruz from January 2008 through May 2008. He is a program committee and the publication chair of IEEE MSST 2010. He served as a reviewer for ACM TECS 2010 ESTIMedia special edition and IEEE RTAS WiP 2010.