[Beowulf] Why need of a scheduler??

Chris Vaughan supercomputer at gmail.com
Wed Jan 9 08:07:20 PST 2008

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 category:
> 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

> Precise, easy and brief reply requested. Thanks to all.
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Christopher Vaughan
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