HP-MPI User's Guide (11th Edition)

Frequently asked questions
Windows specific
Appendix D308
To use the low-level InfiniBand protocol, use the -IBAL flag instead of
-TCP. For example:
R:\> mpirun -IBAL -netaddr 192.168.1.1 -ccp -np 12 rank.exe
The use of -netaddr is not required when using -IBAL, but HP-MPI still
uses this subnet for administration traffic. By default, it will use the TCP
subnet available first in the binding order. This can be found and
changed by going to the Network Connections->Advanced Settings
windows.
IBAL is the desired protocol when using InfiniBand. IBAL performance
for both latency and bandwidth is considerably better than WSD.
For more information, see “Interconnect support” on page 85.
QUESTION: When I use 'mpirun -ccp -np 2 -nodex rank.exe' I only get one
node, not two. Why?
ANSWER
: When using the automatic job submittal feature of mpirun, the
-np X is used to request the number of CPUs for the scheduled job. This
is usually equal to the number of ranks.
But when using -nodex to indicate only one rank/node, the actual
number of CPUs for the job is greater than the number of ranks. Because
compute nodes can have different CPUs on each node, and mpirun
cannot determine the number of CPUs required until the nodes are
allocated to the job, the user must provide the total number of CPUs
desired for the job. Then the -nodex flag will limit the number of ranks
scheduled to just one/node.
In other words, -np X is the number of CPUs for the job, and -nodex is
telling mpirun to only use one CPU/node.
QUESTION: What is a UNC path?
ANSWER: A Universal Naming Convention (UNC) path is a path that is
visible as a network share on all nodes. The basic format is
\\node-name\exported-share-folder\paths
UNC paths are usually required because mapped drives may not be
consistent from node to node, and many times don’t get established for
all logon tokens.
QUESTION: I am using mpirun automatic job submittal to schedule my job
while in C:\tmp, but the job won’t run. Why?