QLogic OFED+ Host Software User Guide, Rev. B

3–TrueScale Cluster Setup and Administration
Host Environment Setup for MPI
Edit the ~/.ssh/config file so that it reads like this:
Host*
ForwardAgent yes
ForwardX11 yes
CheckHostIP no
StrictHostKeyChecking no
This file forwards the key agent requests back to your desktop. When you
log into a front end node, you can use ssh to compute nodes without
passwords.
4. Follow your administrator’s cluster policy for setting up ssh-agent on the
machine where you will be running ssh commands. Alternatively, you can
start the ssh-agent by adding the following line to your ~/.bash_profile
(or equivalent in another shell):
eval ‘ssh-agent‘
Use back quotes rather than single quotes. Programs started in your login
shell can then locate the ssh-agent and query it for keys.
5. Finally, test by logging into the front end node, and from the front end node
to a compute node, as follows:
$ ssh frontend_node_name
$ ssh compute_node_name
For more information, see the man pages for ssh(1), ssh-keygen(1),
ssh-add(1), and ssh-agent(1).
Process Limitation with ssh
Process limitation with ssh is primarily an issue when using the mpirun option
-distributed=off. The default setting is now -distributed=on; therefore, in
most cases, ssh process limitations will not be encountered. This limitation for the
-distributed=off case is described in the following paragraph. See “Process
Limitation with ssh” on page F-19 for an example of an error message associated
with this limitation.
MPI jobs that use more than 10 processes per node may encounter an ssh
throttling mechanism that limits the amount of concurrent per-node connections
to 10. If you need to use more processes, you or your system administrator must
increase the value of MaxStartups in your /etc/ssh/sshd_config file.
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