STAR-CCM+ encounters errors when running MPI jobs with Intel MPI or OpenMPI, displaying the following message:
ib_iface.c:1139 UCX ERROR Invalid active_speed on mlx5_0:1: 128
This issue occurs because the UCX library (v1.8) bundled with STAR-CCM+ only supports Mellanox InfiniBand EDR, while Mellanox InfiniBand NDR is used on Cardinal. As a result, STAR-CCM+ fails to correctly communicate over the newer fabric.
Affected versions
18.18.06.006, 19.04.009 and possibly later versions
Workaround
The solution is to bypass the UCX library for MPI communication by configuring the environment variables appropriately:
For Intel MPI:
export FI_PROVIDER="verbs"
For OpenMPI:
export OMPI_MCA_btl_openib_allow_ib=1
Set these variables before executing the starccm+ command.
