RE: MPI/PBS enforcing restrictions..

This really isn't a Myrinet question, or even an MPI question,
but a PBS question.  I have about 20 minutes experience with PBS
(well, a little more than that, but I am not an expert),
but you are right: PBS doesn't _do_ anything to prevent logins
to the cluster when the nodes are not allocated.  Instead, users
are expected to only use machines that are allocated vis PBS (and
PBS creates an mpi-compatable machines file for useby mpirun).

Instead, as I understand it, users who login to nodes that they
have not allocated "legally" (ie, through PBS) are dealt with
administrativly: ie, they lose their account on the cluster.

Kevin

-----Original Message-----
From: Szabolcs Vrbos
To: myrinet <at> osc.edu
Sent: 4/6/03 1:05 PM
Subject: [Myrinet] MPI/PBS enforcing restrictions..

hello everyone. I would have a question about PBS on myrinet clusters, 
regarding the enforcement of restrictions (such as reserving nodes for a

given job when PBS is used for submitting that job). I read thru the PBS

documentation, I could see they have security implemented, but somehow 
failed to understand an important thing:
It appears to me that even though I queue the job with PBS, in the end,
the 
process is started with an 'mpirun' command. mpirun requires the ability
to 
be able to rsh/ssh to the nodes without a password.
So what will than prevent a user from running a basic 'mpirun' command
from 
his login on the master-node (bypassing PBS, while a PBS queued job is
also 
in progress)?
Or more importantly, how will PBS' mom process on the client node
disable 
user logins to that node while a PBS job is running on that node
(another 
user might log in and run his own processes, right?)?
thank you kindly for clarifying that to a beginner in the world of 
clustering,
-Szabolcs Vrbos

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