Hi!

I am new with MPI.
First I tried an MPI program in a multicore Linux computer, and it worked OK.
My current step is to try to run the same program in a "cluster" composed by two multicore Linux computers, when my final goal is to have a cluster composed by 16 computers (actually, a 64-cores cluster).
I learned that in order to run such a program I need to prevent ssh password requirement when nodes send and/or receive messages among each other. I found the "How to set up SSH Keys" tutorial and setup the two-computer "cluster" according to what is explained in the tutorial.

The result of the 4-steps tutorial procedure is as follows:

the .ssh directory of the first computer has the following files: id_rsa, id_rsa.sub, and known_hosts
the .ssh directory of the second computer has the following files: authorized_keys, and known_hosts
If I do by-hand ssh from the first computer to the second, the second computer does not require password.
If I do by-hand ssh from the second computer to the first, the first computer requires password.

Because of this, I guess, when I run the MPI program, it gets stuck when an ssh connection is tried between the second computer to the first one. Right?

Thus, I request your help to correctly setup password-less ssh capability in the first computer, in order to allow password-less ssh among all the nodes in the cluster (currently, among only two computers). Actually, the question is how I allow password-less ssh connection to the first computer.

I thank you all of you in advance for your help.
Sincerely,
-- Moshe Goldstein