[Beowulf] Why need of a scheduler??

Michael Will mwill at penguincomputing.com
Mon Jan 14 13:51:05 PST 2008

If you only run your application one at a time interacatively, then you
don't need to deal with the overhead
and complexity of a scheduler. However if you are planning to batch
queue up a few runs or several different
applications, then it might be worthwhile to read into torque/maui/moab
and the like.
You mentioned Scyld in your question below, which within the categories
you where interested
in is basically a ressource manager which comes with torque prebundled
to allow scheduling and batch queueing. 
Moab/Taskmaster is then the add-on module to allow more complex


From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org]
On Behalf Of Chris Vaughan
Sent: Wednesday, January 09, 2008 8:07 AM
To: amjad ali
Cc: beowulf at beowulf.org
Subject: Re: [Beowulf] Why need of a scheduler??

On Nov 29, 2007 1:14 PM, amjad ali <amjad11 at gmail.com> wrote:

	Hello all,
	I want to develop and run my parallel code (MPI based) on a
Beowulf cluster. I have no problem as such that many user might log on
to the cluster simultaneously. Suppose that I am free to use cluster
dedicatedly for my single parallel application. 
	1) Do I really need a cluster scheduler installed on the
cluster? Should I use scheduler?

Yes, it makes things easier to control and keep track of.

	2) Is there any effect/benefit on the running of a parallel code
with or without cluster job scheduler?

It depends how many jobs/nodes you run on a 4 node system you would be
fine running something like torque with pbs_sched.  If your requirements
become higher I'd recommend Maui and for those complex environments with
many cores/nodes I'd recommend Moab. 

The benefit is ease of use, the more jobs you run the harder it is to
manage those jobs.  

	3) How you differentiate between cluster scheduler and cluster
resource manager?

One schedules the other gives back information about what resources are

	4) If there is any significant difference between a scheduler
and manager then plaese tell me that which of the fall in which
	OpenPBS, PBS Professional, SGE, Maui, Moab, Torque, Scyld, LSF,
SLURM etc.

Torque=Resource Manager (RM) w/basic scheduling
PBS=(RM) w/some scheduling functionality
SGE=(RM) w/some scheduling functionality 
Moab=Scheduler + More
OpenPBS=Use Torque
LSF=(RM) w/some scheduling functionality
SLURM=(RM) w/basic scheduling
A resource manager manages resources where as a scheduler can schedule
these resources.  Although something like torque resource manager
(OpenPBS) has pbs _sched a fifo scheduler it is still in-adequate in
most environments and you would need a scheduler such as Maui or Moab to
schedule it. 

	5) What is maent by  " PBS/SGE/LSF supports integration with the
Maui scheduler?

You have this mixed up with Moab, Moab can talk to all of these resource
managers and give you a single point of job submission/administration
over all resource managers. 

Cluster Resources provide free support to eval Moab which can be quite
handy http://www.clusterresources.com/pages/products/evaluate.php

	Precise, easy and brief reply requested. Thanks to all. 

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Christopher Vaughan 
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