Optimizing the parameters of the Lustre-file-system-based HPC system for reverse time migration

The article is dedicated to optimizing the computing cluster performance and throughput of the storage with the Lustre file system to perform the reverse time migration task. Optimization is needed because increasing the number of processor cores at first helps to speed up the calculation process, but at some point the calculations start to take more time despite adding more cores with the same storage throughput. This behaviour is caused by the fact that performance gain achieved through parallel operation is offset by increasing delays in the storage that grow nonlinearly as the load increases. To take into account the particularities of this case study, the specific task complexity notion that defines the number of floating point operations per input/output byte was used. This notion and the queuing theory fundamentals were applied to produce a simple formula that links the Lustre file system storage throughput, quantity of storage nodes and the cluster performance in the optimal configuration. LINPACK and SPC-2 benchmark results were used as initial data.