Characterizing Concurrency Control Performance for the PIOUS Parallel File System

Parallel file systems employ data declustering to increase I/O throughput. But because a single read or write operation can generate data accesses on multiple independent storage devices, a concurrency control mechanism must be employed to retain familiar file access semantics. Concurrency control negates some of the performance benefits of data declustering by introducing additional file access overhead. This paper examines the performance characteristics of the transaction-based concurrency control mechanism implemented in the PIOUS parallel file system. Results demonstrate that linearizability of file access operations is provided without loss of scalability or stability. 1 Introduction Parallel computers commonly employ a parallel file system in an effort to offset the growing disparity in computational and I/O capability [dC94]. Parallel file systems address the I/O bottleneck by logically aggregating multiple independent storage devices into a single highperformance storage subsy..