Use of Free Space to Enhance the Performance, Energy Efficiency, and Fault-Tolerance of a File System
Kang Geun Shin · 2009
Abstract : This project has made several significant contributions in enhancing the energy efficiency, performance and fault-tolerance of computer storage systems. First, we developed Power-Aware Virtual Memory (PAVM) that finds and aggregates unmapped and unused memory pages. By powering down unused memory ranks, we can save a significant amount of energy dissipated by the main memory with virtually no performance degradation. Second, we developed the Free Space File System (FS2) based on the popular Ext2 file system by replicating temporally-related data blocks then using the free disk space to place these blocks closer to one another on the disk and thus allowing the disk heads to move less. This results in higher performance, lower energy consumption and higher fault-tolerance at almost zero cost. Finally, we characterized the disk failure patterns and used it to place replicas of critical information on the disk so as to protect them from common disk failures.