Menger is a computer cluster consisting of one master node and eight slave nodes. Each node is equipped with dual 1.7GHz Pentium 4 Xeon processors and 2GB RDRAM. All nodes are connected to each other via fast ethernet switch.

System Access

To login to Menger, use ssh:

"ssh username@octopus.aip.de" or "ssh -l username octopus.aip.de"

The cluster is protected by a firewall. Currently, you can remotely access the computer from charlie.cns.iit.edu and any machine in E1 building. Please change your default password after you login for the first time by typing passwd.

File Storage

The following is recommended for each user.
1. Store your configuration files and program codes in your home directory: /home/username.
2. Run your programs or executables in your directory named /scratch/username.
3. Transfer your data files to some permanent storage place, such as your home directory on charlie.cns.iit.edu.

Compilers on Menger

Release 3.2 of the PGI CDK (Cluster Development Kit) compilers and tools has been installed on the computer. It contains PGI's HPF, Fortran 90, FORTRAN 77, C, and C++ compilers, and profiling(PGPROF) and debugging(PGDBG) tools. A detailed description of the PGI CDK may be found at PGI's website. The documentation for the compilers and tools is provided at the website.

In addition, the GNU compilers(gcc, g++, g77) are also available on the machine.

How to Compile a MPI Parallel Program

Message Passing (MPI) has become increasing popular programming model for parallel processing. The PGI CDK includes pre-configured versions of MPI-CH (an MPI Implementation by Argonne). Compile your programs with pgf77, pgf90, pgcc and pgCC and link with the appropriate MPI libraries.

pgf77 [options] file.f -L/usr/pgi/linux86/lib/ -lfmpich -lmpich	(FORTRAN 77)
pgf90 [options] file.f (link?)	(FORTRAN 90)
pgcc [options] file.c (link?)	(C)
pgCC [options] file.C (link?)	(C++)

How to Run a MPI Program Iteractively

For testing your programs or running small jobs (execution time less than 15 mins),

"mpirun -np N a.out"

How to Submit a Job using PBS

To run your programs for an extensive period of time, please use the batch job submission software PBS (Poratable Batch System).

For example, the following is a simple 'Hello world' fortran program.

program hello
include 'mpif.h'
integer ierr, myproc
call mpi_init(ierr)
call mpi_comm_rank(MPI_COMM_WORLD, myproc, ierr)
print *, "Hello world! I'm node", myproc
call mpi_finalize(ierr)
end

To compile, "pgf77 -o mpihello mpihello.f -lfmpich -lmpich".

To run the program using PBS, first edit a file named 'mpihello.pbs' whose content is as follows:

#!/bin/csh
#PBS -l nodes=2
#PBS -r n
# This is a PBS job submission script. It assumes that there are 2 2-processor
# nodes in the PBS cluster. It also assumes that mpihello has been compiled
# in the local directory by typing:
#
# % pgf77 -o mpihello mpihello.f -lfmpich -lmpich
#
# PBS will reserve 2 nodes and then execute this script. "mpirun" uses
# the PBS_NODEFILE environment variable as the list of machines on which
# # IMPORTANT NOTE: Be sure to modify the "cd" command below to switch
# to the directory in which you are currently working! Also modify the
# setting of the PGI environment variable as appropriate for your
# installation
#
setenv PGI /usr/pgi
set path=($PGI/linux86/bin $path)
cd /scratch/test
/usr/pgi/linux86/bin/mpirun -v -np 4 mpihello

"qsub mpihello.pbs"

You can find a copy of the example files 'mpihello.f' and 'mpihello.pbs' in the directory '/scratch.host/test'

How to Check a Job Status using PBS

"qstat "

How to Delete a Submitted Job using PBS

"qdel 'job_id' "