IOR

IOR – Interleaved or Random is a high-performance computing (HPC) benchmark application used to test parallel file system performance. It’s an MPI-based tool that measures I/O performance with various access patterns, file sizes, and inter-processor communication strategies.

It is widely used in HPC environments to benchmark file systems like Lustre, but it can be run on any POSIX-compliant file system. IOR simulates various parallel I/O workloads, like sequential and random read/write operations, to evaluate the performance of storage systems. It uses multiple processes that synchronize using the Message Passing Interface (MPI) to generate I/O load on a file system, and tests aspects like read/write speed, peak metadata rates (with its companion tool, mdtest), and how the system performs under different configurations, such as using a shared file or one file per process.