Product specifications

1–Overview of the Release
Other Information
D000069-024 1-17
 When users increase the number of processes beyond the number of open
files allowed by ulimit, mpirun prints an error message. The ulimit for the
number of open files is typically 1024 on both Red Hat and SLES. The
message will look similar to the following:
MPIRUN.up001: Warning: ulimit for the number of open files is
only 1024, but this mpirun request requires at least number of
files open files (sockets). The shell ulimit for open files
needs to be increased. This is due to limit:
descriptors 1024
The ulimit can be increased; QLogic recommends an increase of
approximately 20 percent over the number of CPUs. For example, in the
case of 2048 CPUs, ulimit could be increased to 2500: ulimit -n 2500.
Increase the ulimit only on the host where mpirun was started, unless the
mode of operation allows mpirun from any node.