[Beowulf] Restricting users from ssh into nodes

Prentice Bisbal prentice.bisbal at rutgers.edu
Thu Aug 22 11:00:20 PDT 2013


On 08/20/2013 02:03 PM, Mark Hahn wrote:
>> 1. Many people's job scripts use ssh either directly (to say clean up /tmp)
>> or indirectly from mpirun.
> sure.
>
>> (good mpirun's use the batch engine's per-node
>> daemon to launch the binaries not ssh).
> why should a scheduler have daemons cluttering up compute nodes?
> also, do you really launch so many very big but very short jobs
> that startup time is a serious concern?  I'm questioning assumptions here.
>

It's not about reducing startup time. It's about controlling the jobs 
accurately. With SGE, all jobs started are children of the sge_sheperd 
processes (which gets started by the sge_execd daemon). This allows SGE 
to have ultimate control over the jobs  (suspend resume, kill, etc.) and 
provide accurate process accounting. When you just use SSH, can you 
provide that level of control?

And if you really want to be a pro, you create a prolog script that 
creates a unique temp directory for the user, that they can reference 
with an environment variable (say, SCRATCH, or SGE_TMP or something 
similar), that they can use while their job is running, and then have an 
epilog script that will automatically clean it up after the job completes.

If you're users must clean up /tmp themselves after jobs are done, 
something is not right.

Prentice



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