[MPICH] MPICH Connection Problem

[Jan Wagner]

Hi,

On Thu, 15 Mar 2007, Natarajan, Senthil wrote:
> I am using MPICH1.2.4 on Linux. I installed with the option -rsh=ssh.
>
> After successfully installed, I am trying to run a simple mpi job with
> the two machines.
>
> I have generated the key pair (ssh-keygen) and copied to other machine,
> and I can ssh between the machines with out password.
>
> I am trying to run a simple mpi job, but it with out trying to connect 
> other machine, complains about connection refused.

Just a thought, but if you check with e.g. 'ps ax' what processes are 
started, you could see with what ssh parameters mpich tries to execute the 
remote programs.

But ok, at least from your mpich output it looks like it is still trying 
to use old rsh instead of ssh.

Try setting
$ export P4_RSHCOMMAND=ssh
$ export RSHCOMMAND=ssh

and do the mpirun again. Then it should use ssh. If not, try configuring 
and compiling again, this time with -rsh=RSHCOMMAND.

(The 1.2.5 and 1.2.7 configure/compile is a bit strange, when I 
too compiled with -rsh=ssh a few days ago it did not want to use ssh. 
Compiling with -rsh=RSHCOMMAND complained to me near the compile end that 
I should not use this "old" option, but use -rsh=ssh instead. But 
the complained about RSHCOMMAND works! In contrast to the "new" option. 
Odd. Well go figure... ;-) )

Oh and also note that you'd probably need to stop iptables/ipchains, or 
configure them properly, as with ssh mpich tries to set up some ssh port 
forwarding / port tunneling. Connections will time out.

  - Jan