Hi, Apologies for the delay in response. My comments inline below. On 10/15/2016 07:40 PM, Mahdi, Sam wrote:

Hello everyone,

I am attempting to run a single program on 32 cores split across 4 computers (So each computer has 8 cores). I am attempting to use mpich for this. I currently am just testing on 2 computers, I have the program installed on both, as well as mpich installed on both. I have created a register key and can login in using ssh into the other computer without a password. I have come across 2 problems. One, when I attempt to connect using the mpirun -np 3 --host a (the IP of the computer I am attempting to connect to) hostname I recieve the error unable to connect from "localhost.localdomain" to "localhost.localdomain"

This is indicating my computers "localhost.localdomain" is attempting to connect to another "localhost.localdomain". How can I change this so that it connects via my IP to the other computers IP?

Secondly, I attempted to use a host file instead using the hydra process wiki. I created a hosts file with just the IP of the computer I am attempting to connect to. When I type in the command mpiexec -f hosts -n 4 ./applic

I get this error [[email protected]] HYDU_parse_hostfile (./utils/args/args.c:323): unable to open host file: hosts

along with other errors of unable to parse hostfile, match handler etc. I assume this is all due to it being unable to read the host file. Is there any specific place I should save my hosts file? I have it saved directly on my Desktop. I have attempted to indicate the full path where it is located, but I still get the same error.

There is no required location for the hosts file. If you are specifying full path and there are still issues, it may be a formatting issue. Can you paste or attach the contents of your hosts file so we can confirm the format is good?

For the first problem, I have read that I need to change /etc/hosts manually by using the sudo command to manually enter the IP of the computer I am attempting to connect to in the /etc/hosts file. I assume the computer is attempting to connect to itself (set up the program first on its own core, then send it to another, hence attempting to start it on localhost.localdomain).

For the second problem, I have attempted to add run the command mpirun --host my computer IP, the other computer IP ./program

This format should be okay for your purposes. What happens if you try: mpirun --host my computer IP, the other computer IP /bin/hostname If the hostnames of each host are echoed to the command-line, then job launch is successful and the issues is during connection setup during MPI_Init. Ken _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss