User-Level Parallel File I/O

Parallel disk I/O subsystems are becoming more important in today’s large-scale parallel machines. Parallel disk systems provide a significant boost in I/O performance reducing the gap between processor and disk speeds. We describe a Unix-like file I/O user interface, implemented in a parallel file I/O subsystem on an MIMD machine, the nCUBE 2. Based on message passing, we develop parallel disk read/write algorithms to achieve higher parallelism when more disk drives are used. We use the closed queuing network model to analyze the effect of some tunable system parameters for our parallel file system. We then performed simulation experiments in order to obtain more realistic performance data, by comparing the original vendor-supplied file system with ours. The results indicate that the speedup in I/O performance is almost equal to the number of disk drives we use. Thus, our user-level parallel file I/O approach will provide scalable I/O performance.