Performance evaluation of software RAID vs. hardware RAID for Parallel Virtual File System

Linux clusters of commodity computer systems and interconnects have become the fastest growing choice for building cost-effective high-performance parallel computing systems. The Parallel Virtual File System (PVFS) could potentially fulfill the requirements of large I/O-intensive parallel applications. It provides a high-performance parallel file system by striping file data across multiple cluster nodes, called I/O nodes. Therefore, the choice of storage devices on I/O nodes is crucial to PVFS. We study the impact of software RAIDs and hardware RAIDs on the performance of PVFS when they are used on I/O nodes. We first establish a baseline performance of both RAIDs in a stand-alone configuration. We then present the performance of PVFS for a workload comprising concurrent reads and writes using ROMIO MPI-IO, and for the BTIO benchmark with a noncontiguous access pattern. We found that software RAIDs have a comparable performance to hardware RAIDs, except for write operations that require file synchronization.