Parallel batch jobs on beowulf?

[Eray Ozkural (exa)]

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Hi Gary,

On Tuesday 02 October 2001 01:34 am, Gary Stiehr wrote:
> Hi,
>    PBS is perfectly acceptable for this type of use.  Each job can
> request all of the nodes or just a subset of them.  The job is queued
> until the requested number of nodes is available.  You are still able to
> run MPI/PVM programs on the nodes in an interactive way when using PBS
> but this may be confusing/misleading to the users of the cluster.
>

Thanks for your suggestion. I'll look into OpenPBS.

I have one question though. How would I prevent users from starting parallel 
jobs while a PBS job is running? Since parallel codes don't run in a flash, 
it's highly likely that another user might, unknowingly, interfere with a 
parallel job. (and perturb its wall-clock performance) Is there a nice way to 
'lock' a node when a parallel job starts on a node and 'release' it when it 
terminates so that no other user process can be started on it while the 
parallel job is running?

Since all nodes are accessed via rsh it could be on that level, or at a lower 
level I guess, but I'm uncertain as to how this should be implemented in a 
reliable way (so that it does not corrupt otherwise normal operations)

>     You can also set PBS to use your nodes in a "time-shared" manner.
> This way, PBS can allocate more than one job to each node.  When you
> need to have only one job per node, you can configure the nodes as
> "exclusive" nodes.  I hope this helps.

It seems I'd use exclusive nodes. Could I also allocate them for a specific 
time interval? For instance, having batch jobs run in the night... But I 
don't know if that would be a good sol'n.

Thanks,

- -- 
Eray Ozkural (exa) <erayo at cs.bilkent.edu.tr>
Comp. Sci. Dept., Bilkent University, Ankara
www: http://www.cs.bilkent.edu.tr/~erayo
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