Getting started

Access to the cluster

Access is via secure shell (ssh) only; telnet and rlogin are strictly prohibited. If you need to change your password or default shell, ssh to and make the change(s) there; changes made anywhere else will revert to the old value. Your home directory is assigned to one of the frontend machines. It is most efficient to log in to your home machine initially and to use it for most work since that minimizes NFS traffic. However, you may ssh to any frontend machine as needed. You should not log on to the numbered nodes. The frontends are for routine work such as editing and compiling and may also be used for short debugging runs. Production runs should be submitted to the nodes via either the PBS queues or via Legion.

Compiling jobs on the frontend machines

We provide the gcc ("gnu compiler collection") on all nodes. This includes gcc (C), g++ (C++), and g77 (Fortran 77). The current version of this compiler set is 2.95.2.

Fortran 90/95 on Centurion

Alpha The Compaq Fortran 90 compiler fort and its associated debugger ladebug are available on scout.

Intel We provide the Portland Group Fortran 90 and the Absoft Fortran 95 compilers. The Portland Group compiler, pgf90, is on spica, as is their Fortran 77 compiler pgf77; this compiler is useful for codes which are mostly Fortran 77 but with certain widely supported extensions such as Cray pointers. In addition, the Portland Group debugger pgdbg is located on spica. The Absoft f90 and f77 compilers are on thuban; Absoft also supports most common Fortran 77 extensions in its f77 product. The Absoft debugger fx is also located on thuban. The two compilers offer similar performance, with one or the other having an advantage on different codes. If you need Fortran 95 specifically then you must use the Absoft compiler.

See for more information about these compilers.

Running jobs

For parallel jobs, the Myrinet MPI library on nodes centurion000 through centurion063 may be used via the PBS batch queue system, through the frontend scout. For instructions on submitting jobs to PBS, see

Other nodes in the cluster may be used via Legion only. Legion supports both the MPI and the PVM APIs, and may also be used to run sequential jobs through the commands legion_run/legion_run_multi. For more information about using Legion, consult the online documentation at this Web site. The tutorials and cookbooks are especially helpful to new users. For specific questions you may email

[Centurion Home] [Centurion Overview]
[Alert] [Using Centurion] [Photos] [Demo Applications]
[Legion Home]

Last modified: Thu Feb 17 11:27:25 2000