Performance Study of Non-volatile Memories on a High-End Supercomputer

The first exa-scale supercomputers are expected to be operational in China, USA, Japan and Europe within the early 2020’s. This allows scientists to execute applications at extreme scale with more than \(10^{18}\) floating point operations per second (exa-FLOPS). However, the number of FLOPS is not the only parameter that determines the final performance. In order to store intermediate results or to provide fault tolerance, most applications need to perform a considerable amount of I/O operations during runtime. The performance of those operations is determined by the throughput from volatile (e.g. DRAM) to non-volatile stable storage. Regarding the slow growth in network bandwidth compared to the computing capacity on the nodes, it is highly beneficial to deploy local stable storage such as the new non-volatile memories (NVMe), in order to avoid the transfer through the network to the parallel file system. In this work, we analyse the performance of three different storage levels of the CTE-POWER9 cluster, located at the Barcelona Supercomputing Center (BSC). We compare the throughputs of SSD, NVMe on the nodes to the GPFS under various scenarios and settings. We measured a maximum performance on 16 nodes of 83 GB/s using NVMe devices, 5.6 GB/s for SSD devices and 4.4 GB/s for writes to the GPFS.