Yes, Mark, you are right.
Passwordless ssh is not a strict requirement,
although it is a simple way to make things work.
Yes, host based trust is better than unencrypted private keys.
I don't even know if the cluster in question is
connected to the Internet, though.
My suggestions were directed to someone who is still using
MPICH-1, claimed to have trouble with it,
not to be familiar to clusters and MPI,
and to have a pressing deadline.
Therefore, I thought it would be more helpful to give him
simple and focused suggestions,
rather than a full gamut of possibilities.
I guess it would be a great help to him if you post
simple instructions (or a link) on how to setup passwordless ssh
through host based trust.
Regards,
Gus Correa
Mark Hahn wrote:
In MPICH2 you need to establish passwordless ssh (not rsh!)
connection across your machines.
it should be said that mpich2 doesn't strictly require this.
all mpi flavors can operate with other spawning methods - some have
hooks to be spawned by the resource manager, for instance, which
bypasses ssh/rsh type access.
In OpenMPI you also need to establish passwordless ssh connection
same for OpenMPI: doesn't actually require passwordless ssh.
but if you do want passwordless ssh, IMO the only sane solution is to
configure hostbased trust. having an unencrypted private key in your
home directory is hideous (moral equivalent of putting your password in
a file, in the clear...)
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