Broken Intermediate Link

C – Troubleshooting InfiniPath MPI Troubleshooting

C.6.1

Sometimes message traffic passes through the fabric while other traffic appears to be blocked. In this case, MPI jobs fail to run.

In large cluster configurations, switches may be attached to other switches in order to supply the necessary inter-node connectivity. Problems with these inter-switch (or intermediate) links are sometime more difficult to diagnose than failure of the final link between a switch and a node. The failure of an intermediate link may allow some traffic to pass through the fabric while other traffic is blocked or degraded.

If you encounter such behavior in a multi-layer fabric, check that all switch cable connections are correct. Statistics for managed switches are available on a per-port basis, and may help with debugging. See your switch vendor for more information.

C.7

Performance Issues

Performance issues that are currently being addressed are covered in this section.

C.7.1

MVAPICH Performance Issues

MVAPICH over OpenFabrics over InfiniPath performance tuning has not yet been done. Improved performance will be delivered in future releases.

C.8

InfiniPath MPI Troubleshooting

Problems specific to compiling and running MPI programs are detailed below.

C.8.1

Mixed Releases of MPI RPMs

Make sure that all of the MPI RPMs are from the same release. When using mpirun, an error message will occur if different components of the MPI RPMs are from different releases. This is a sample message in the case where mpirun from release 1.3 is being used with a 2.0 library:

$ mpirun -np 2 -m ~/tmp/x2 osu_latency

MPI_runscript-xqa-14.0: ssh -x> Cannot detect InfiniPath interconnect.

MPI_runscript-xqa-14.0: ssh -x> Seek help on loading InfiniPath interconnect driver.

MPI_runscript-xqa-15.1: ssh -x> Cannot detect InfiniPath interconnect.

MPI_runscript-xqa-15.1: ssh -x> Seek help on loading InfiniPath interconnect driver.

MPIRUN: Node program(s) exited during connection setup

IB6054601-00 D

C-13

IB6054601-00 D specifications

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Q-Logic IB6054601-00 D manual Broken Intermediate Link, Mvapich Performance Issues

Models: IB6054601-00 D