Re: [condor-users] How to configure more Condor VMs than actual CPUs?

[Angel de Vicente <angelv@xxxxxxxxx>]

Thanks Burt,

yes, that seemed to do the trick. I don't know if the authors of the paper I was
consulting (Condor and the Bologna Batch System by Peter Couvares, Paolo
Mazzanti, Daniela Bortolotti or Franco Semeria) are listening, but if they are I
would suggest them to include this in their document to make this point a bit
clearer. Also I found in another version of the document
(http://www.bo.infn.it/calcolo/condor/INFN-bbs.pdf) that the expression IsOwner
= False is needed.

But I have a couple of questions:

1) Our nodes in the Beowulf cluster have 2GB of RAM each, but by lying about the
   number of CPUS, Condor reports each VM as having just a portion of that
   (proportional to the number of CPUS, for example 512MB if 4 VMs). Will I be
   able to run jobs that require a lot of RAM or will Condor enforce that each
   VM will run only jobs that need 512MB?

2) The setting in the Condor Bologna Batch System paper is described for vanilla
   jobs. What I want is to do something similar for MPI jobs (which is the main
   type of job in our cluster), but when I tried to submit an MPI job with the
   described settings the job would just enter the queue, and stay there
   forever. Is there a way to configure more VMs than actual CPUs and still be
   able to run MPI jobs? Any success stories?


Thanks a lot,
Angel de Vicente


Burt Holzman writes:
 > Angel de Vicente wrote:
 > 
 > > How can you do that? In a single CPU machine I've tried two things and obtained
 > > two types of errors:
 > 
 > > 1) Just setting NUM_VIRTUAL_MACHINES = 2 
 > > 2) Defining VIRTUAL_MACHINE_TYPE_1 = 50%
 > 
 > For our dual-CPU machines, I found that setting NUM_CPUS = 4 in 
 > condor_config seemed to do the trick.
 > 
 > - B
 > 
 > -- 
 > Dr. Burt Holzman
 > Chemistry Department / PHOBOS Experiment
 > Brookhaven National Laboratory
 > 
 > 
 > Condor Support Information:
 > http://www.cs.wisc.edu/condor/condor-support/
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