Multiple node groups in Scyld

Karl Kosack kosack at
Tue Jun 12 14:00:56 PDT 2001

I have recently set up a beowulf cluster for scientific computing using
the Scyld distribution.  Scyld was very easy to set up and configure, but
I have one major question for which I can't seem to find an answer: How
can I run more than one MPI program on the cluster on different ranges of

For example, there are times where I would like to run one program
on nodes 0-3 and another on 4-8.  The "mpirun" command that comes with
Scyld only seems to let you supply a number of node numbers and not a

If I run "mpirun --nodes 4 myprog1" and then "mpirun --nodes 4 myprog2"
then myprog1 and myprog2 both run on nodes 0-3.

I know in other MPI  implementations, it is possible to create a
file of machine names which specifies which nodes to use for a particular
job, but I can't seem to find that capability in the Scyld distribution.
I imagine there must be a simple way to do this, since a large cluster
wouldn't be very useful without it.  Can anyone help me?


  Karl Kosack <kosack at>
  Physics Department
  Washington University
  One Brookings Drive, Box 1105
  St. Louis, MO 63130

 office: (314) 935-5035  (Compton 267)

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