>I tried disabling the firewall real quick and still got the same results.

Disabling a potential error source for trial and error is always a good thing to isolate a problem.

However, at one point I got the following error:

[proxy:0:1@Pi02] launch_procs (/home/pi/mpich2/mpich-3.1/src/pm/hydra/pm/pmiserv/pmip_cb.c:641): unable to change wdir to /home/pi/mpi_test (No such file or directory)

So I scratched my head and wondered if it was something as silly as the fact that I was calling mpiexec from a directory that existed on Pi01 and not on the other three. I quickly created the same directory on the other three Pis and bam:

pi@Pi01 ~/mpi_test $ mpiexec -f machinefile -n 4 hostname

Pi01

Pi04

Pi03

Pi02

Was it really that simple?

Thanks.

Ken

Yes, That *IS* possible ! J   As you mention it now – I had the same problem some years ago. Unfortunately I didn’t remember in time sparing you from dealing with  the same trouble.

Ursula