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<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>Hello
Amjad, </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> beowulf-bounces@beowulf.org
[mailto:beowulf-bounces@beowulf.org]<B>On Behalf Of </B>amjad
ali<BR><B>Sent:</B> November 29, 2007 8:14 AM<BR><B>To:</B>
beowulf@beowulf.org<BR><B>Subject:</B> [Beowulf] Why need of a
scheduler??<BR><BR></FONT></DIV>
<DIV>Hello all,</DIV>
<DIV> </DIV>
<DIV>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. </DIV>
<DIV> </DIV>
<DIV>1) Do I really need a cluster scheduler installed on the cluster? Should
I use scheduler?<BR><SPAN class=580322515-29112007><FONT face=Arial
color=#0000ff size=2>[Bill Bryce] If you are the only user of the cluster
then you don't *really* need a scheduler, however if you want to queue
up lots of jobs on your cluster and 'just let it run' then a
scheduler is needed. </FONT></SPAN></DIV>
<DIV> </DIV>
<DIV>2) Is there any effect/benefit on the running of a parallel code with or
without cluster job scheduler?<BR><SPAN class=580322515-29112007><FONT
face=Arial color=#0000ff size=2>[Bill Bryce] There are some
benefits. Most schedulers/resource managers are integrated with various
implementations of MPI so that task startup and task cleanup is
controlled by the scheduler/resource manager. What this means for
you is less time spent cleaning up dead processes on the nodes in your
cluster. Schedulers and resource managers also have job control which
allows you to suspend and resume the entire parallel job - sometimes
this is useful.</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>The
scheduler and resource manager are really useful when you want to run
many jobs on your cluster - when this happens the scheduler will decide
which nodes in the cluster will be allocated for your parallel job based
on the scheduling policy (or policies) enabled in the scheduler. Overall
a good scheduler and resource manager combination will keep the whole cluster
busy running your work whereas manually running jobs relies on *you* to
be the scheduler which is not as efficient as a
scheduler.</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>One
of the distinct advantages of a scheduler/resource manager is when things
go wrong. All scheduler/resource managers provide mechanisms to
handle job failure, host failure and re-running the job automatically.
So if your job fails at say 3 in the morning the system will automatically
recover and start your work over again.</FONT> </SPAN></DIV>
<DIV> </DIV>
<DIV>3) How you differentiate between cluster scheduler and cluster
resource manager?<BR><SPAN class=580322515-29112007><FONT face=Arial
color=#0000ff size=2>[Bill Bryce] </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>I'm
sure you'll get more responses on this question but here is my
two cents worth....</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>The
cluster scheduler is only concerned about scheduling work to the
available resources (or future availablity of resources), so FCFS, Fairshare,
Backfill, pre-emption, Quality of Services, are all valid scheduling policies
used by a scheduler to determine when your job will run and
what resources the job will use to run on the
cluster.</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>The
resource manager is responsible for discovering, monitoring and aggregating
resources in your cluster, so that this information can be used by the
scheduler to make decisions. Resources can be pretty much
anything, but to keep it simple resources are the hosts, cpus, cores, memory,
network interfaces, etc... </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007> </SPAN></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV>4) If there is any significant difference between a scheduler and manager
then plaese tell me that which of the fall in which category:<BR><SPAN
class=580322515-29112007><FONT face=Arial color=#0000ff size=2>[Bill
Bryce] </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>Ah
now this is where, depending on who you talk to; you get different
answers...</FONT> </SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2>OpenPBS, PBSPro, SGE, LSF, Torque - are all both resource managers and
schedulers.</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>Maui
& Moab are Schedulers - and require a resource manager (so one of the
above)</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2>Scyld - is much more than just a resource manager/scheduler it is an
entire collection of software for running a Beowulf cluster - you could say
Scyld is the whole 'cluster stack of software'. Resource managers and
Schedulers can run on a Scyld cluster.</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2>SLURM - is a resource manager and is quite good at doing resource
allocations for parallel jobs. SLURM is used in conjunction with a
Scheduler (or one of the Scheduler/Resource managers)</FONT></SPAN></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV>OpenPBS, PBS Professional, SGE, Maui, Moab, Torque, Scyld, LSF, SLURM
etc.</DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV><FONT face=Arial
color=#0000ff size=2></FONT><FONT face=Arial color=#0000ff size=2></FONT><FONT
face=Arial color=#0000ff size=2></FONT>
<DIV><BR><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2> </FONT></SPAN>5) What is maent by " PBS/SGE/LSF
supports integration with the Maui scheduler?<BR><SPAN
class=580322515-29112007><FONT face=Arial color=#0000ff size=2>[Bill
Bryce] </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff size=2>It
simply means that Maui can sit on top of PBS/SGE/LSF and 'take
control of scheduling' by turing off or ignoring the built in scheduler
in PBS/SGE/LSF. </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2>Regards, </FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007></SPAN> </DIV>
<DIV><SPAN class=580322515-29112007><FONT face=Arial color=#0000ff
size=2>Bill.</FONT></SPAN></DIV>
<DIV><SPAN class=580322515-29112007> </SPAN></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV>Precise, easy and brief reply requested. Thanks to all. </DIV>
<DIV> </DIV>
<DIV> </DIV></BLOCKQUOTE>
!DSPAM:474edfb6234081923983023!
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