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

Understanding HP-MPI
MPI options
Chapter 3156
variable MPI_MAX_REMSH. When the number of daemons required is
greater than MPI_MAX_REMSH, mpirun will create only MPI_MAX_REMSH
number of remote daemons directly. The directly created daemons will
then create the remaining daemons using an n-ary tree, where n is the
value of MPI_MAX_REMSH. Although this process is generally transparent
to the user, the new startup requires that each node in the cluster is able
to use the specified MPI_REMSH command (e.g. rsh, ssh) to each node in
the cluster without a password. The value of MPI_MAX_REMSH is used on a
per-world basis. Therefore, applications which spawn a large number of
worlds may need to use a small value for MPI_MAX_REMSH.
MPI_MAX_REMSH is only relevant when using the -f option to mpirun. The
default value is 20.
MPI_NETADDR Allows control of the selection process for TCP/IP
connections. The same functionality can be accessed by using the
-netaddr option to mpirun. See “mpirun options” on page 119 for more
information.
MPI_REMSH By default, HP-MPI attempts to use ssh on Linux and remsh
on HP-UX. On Linux, we recommend that ssh users set
StrictHostKeyChecking=no in their ~/.ssh/config.
To use rsh on Linux instead, the following script needs to be run as root
on each node in the cluster:
% /opt/hpmpi/etc/mpi.remsh.default
Or, to use rsh on Linux, use the alternative method of manually
populating the files /etc/profile.d/hpmpi.csh and
/etc/profile.d/hpmpi.sh with the following settings respectively:
setenv MPI_REMSH rsh
export MPI_REMSH=rsh
On HP-UX, MPI_REMSH specifies a command other than the default
remsh to start remote processes. The mpirun, mpijob, and mpiclean
utilities support MPI_REMSH. For example, you can set the environment
variable to use a secure shell:
% setenv MPI_REMSH /bin/ssh
HP-MPI allows users to specify the remote execution tool to use when
HP-MPI needs to start processes on remote hosts. The tool specified must
have a call interface similar to that of the standard utilities: rsh, remsh
and ssh.