Adaptive disk striping for parallel input/output

As disk capacities continue to rise more rapidly than transfer rates, adaptive, redundant striping smoothly trades capacity for higher performance. We developed a fuzzy logic rule base for adaptive, redundant striping of files across multiple disks. This rule base is based on a queuing model of disk contention that includes file request sizes and disk hardware parameters. At low loads, the rule base stripes aggressively to minimize response time. As loads rise, it stripes less aggressively to maximize aggregate throughput. This adaptive striping rule base is incorporated into our second generation Portable Parallel File System (PPFS II). Experimental results showed that the analytical models of disk striping are capable of accurately predicting file system behavior. Also, it is shown that, depending on the access pattern, adaptive striping can double the input/output performance compared to striping with fixed distribution parameters.