Filling the Memory Access Gap:
A Case for On-Chip Magnetic Storage
Carnegie Mellon University Technical Report CMU-CS-99-174, November 1999.
Steven W. Schlosser, John Linwood Griffin David F. Nagle, Gregory R. Ganger
Dept. Electrical and Computer Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
For decades, the memory hierarchy access gap has plagued computer architects with the RAM/disk gap widening to about 6 orders of magnitude in 1999. However, an exciting new storage technology based on MicroElectroMechanical Systems (MEMS) is poised to fill a large portion of this performance gap, delivering significant performance improvements and enabling many new types of applications. This research explores the impact MEMS-based storage will have on computer systems. Working closely with researchers building MEMS-based storage devices, we examine the performance impact of several design points. Results from five different applications show that MEMS-based storage can reduce application I/O stall times by 80-99%, with overall performance improvements ranging from 1.1X to 20X for these applications. Most of these improvements result from the fact that average access times for MEMS-based storage are 5 times faster than disks (e.g., 1-3ms). Others result from fundamental differences in the physical behavior of MEMS-based storage. Combined, these characteristics create numerous opportunities for restructuring the storage/memory hierarchy.