[torqueusers] What is the difference between PBS and Torque?

Chris Samuel csamuel at vpac.org
Sat Feb 23 20:56:04 MST 2008

----- "Omer Khalid" <Omer.Khalid at cern.ch> wrote:

> Hi James,

Hello Omer,

> Thanks for your prompt response and explaining me the history of
> Torque and its architecture. So pbs_server is resource manager that
> takes care of the resource provisioning, pbs_sched/Maui for scheduling
> the job and resource allocation and pbs_mom for monitoring the
> computer node.. right??

That sounds about right.

> So I guess that qmgr is part of pbs_server to set up the queues.

It's actually a command that talks to the pbs_server process.

> Now let's say for a cluster of 20 nodes, 5 different queues are specified
> based on different type of execution priorities. Can all nodes consume
> jobs from any of the queues

Yes - though you can put rules into Maui/Moab to govern
what you want to happen here.

> or they are configured for specific queues?

Not really.

> And what happens when a job arrives at the pbs_server? Does
> pbs_sched/Maui get the status info from the pbs_server about the
> available resources, and based on a job's requirements put that into a
> specific queue?

No, queues are more of a Torque concept and Maui maps
them to classes. pbs_sched might be more constrained though.

> Does it also allocate a specific execution node for
> that particular job

Yes, it does.

> or the compute node reads the job from a certain queue?

No, it's a push system, rather than a pull one.

> In this case, adding dynamic nodes is possible?

Not easily.

> My thoughts pretty are disjointed but I would much appreciate the
> explanations..

So are mine! :-)

Christopher Samuel - (03) 9925 4751 - Systems Manager
 The Victorian Partnership for Advanced Computing
 P.O. Box 201, Carlton South, VIC 3053, Australia
VPAC is a not-for-profit Registered Research Agency

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