[Beowulf] picking out a job scheduler

[Chris Samuel]

On Thursday 04 January 2007 22:16, Reuti wrote:

> Linda and PVM* need some kind of rsh/ssh between the nodes, and I  
> didn't get a clue up to now to convince Linda to use the PBS TM of  
> Torque.

Torque provides a pbsdsh command that uses the TM interface and acts like the 
various DSH variants.  What it doesn't appear to be able to do (which I've 
just discovered) is to be able to only run once per node in the job. Hmm..

> As you mentioned in your other post about keeping control of   
> MPI processes, the similar thing to TM is the qrsh command in SGE,  
> which will replace rsh/ssh and SGE is controlling this way these  
> spawned processes on the nodes.

Sounds very similar to pbsdsh in the way it works.

> I'm also always looking in a cluster setup, without any common rsh/ssh
> between the nodes at all, where users could by accident start processes out
> of control of the queuing system on the nodes.

Exactly.  What we do here is a hack in the /etc/profile that checks for the 
existence of $PBS_ENVIRONMENT and kicks them off with a message about only 
being permitted to access the node if you have a job on it.  Ugly, but it 
works.

Newer versions of Torque have a PAM module contributed by Jim Prewett which 
will check the user against the current list of Torque jobs on a node and 
only permit access if they have a job on the node.

We prefer to only allow access via a PBS jobs which is why we still use our 
hack, but the PAM module might be a handy backstop for us.

cheers!
Chris
-- 
 Christopher Samuel - (03)9925 4751 - VPAC Deputy Systems Manager
 Victorian Partnership for Advanced Computing http://www.vpac.org/
 Bldg 91, 110 Victoria Street, Carlton South, VIC 3053, Australia

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