[Beowulf] Restricting users from ssh into nodes

Reuti reuti at staff.uni-marburg.de
Thu Aug 22 11:05:06 PDT 2013


Am 22.08.2013 um 20:00 schrieb Prentice Bisbal:

> 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?

+1


> 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 

One you get for free in SGE and it can be accessed by $TMPDIR inside the jobscript. A creation in a prolog is only necessary in case you need a second one (maybe a global one in addition to the one on the node).

-- Reuti


> 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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