Overview of the NIST SP2


The IBM Scalable POWERparallel System 2 (SP2) is a distributed memory multiprocessor consisting of a collection of RS6000 workstation nodes (running the AIX operating system) together with a Scalable POWERparallel Switch providing communication between the nodes.

SP2 hardware information (site specific)

Photo of the High Performance Switch:

(click to enlarge)

For recent changes to the local configuration, see What's New with the SP2 system at the NIST SP2 website.

Interactive vs. batch access

The current NIST SP2 configuration allows users to interactively access the front-end machine danube.nist.gov and a small test pool of four nodes (grand17-grand20). The remaining nodes are available for batch jobs.

This interactive pool is intended to be used only when interactivity is absolutely required, for example, in program debugging and run-time performance monitoring.
To execute large parallel jobs using the SP2 nodes, users must submit their jobs through a batch system, which partitions the machine into node pools and controls access to these pools so that jobs are single-threaded (i.e. when you run on a set of SP2 nodes, you are in a "dedicated" environment).


Sources of information and documentation


There is quite a bit of electronic information you can browse through to get acquainted with the SP2 and PVM or MPI.

Locally, you will find IBM-supplied SP2 docs (in postscript) on danube.nist.gov in the directory /doc. For more information on the differences between PVM and MPI, see the section on Choosing a Message Passing Library.

Online man-pages are another valuable source of information, in particular for quick information about message passing routine syntax. Man-pages are available for both MPI and PVM, and are accessed by typing: man routine. Note, although information is provided for Fortran as well as C, you must request the information using the C routine name.

Another local source of information is a documentation system called InfoExplorer, located on danube. It has a X-windows user-interface, and so you must remember to set your $DISPLAY environment variable to your local console and add danube.nist.gov to your xhost list. Use the command "setenv DISPLAY your_console.nist.gov:0.0" on danube to set the DISPLAY variable, and the command "xhost +danube.nist.gov" on your console to allow danube to open a window on your console. InfoExplorer can then be invoked with the command "info [-l libraryname]", where libraryname can be used to specify the user manual of interest. Currently, the following are available:

         info -l xlf    (Fortran manuals)
         info -l pe     (Programming Environment manuals)
         info -l wb     (Workbench manuals)
         info -l LoadL  (LoadLeveler manuals)
         info -l pvme   (pvm3 manual)
If you start up InfoExplorer without a library specified, you can link to one later in the "Task & Topic Index" window (not through the "Welcome to the InfoExplorer..." window, which also appears) by pulling down the menu labelled "info" and choosing "Library" and "Select".

The SP User Group Home Page What's New with the SP2 system at Cornell has links to current discussion groups, educational sites, and a host of other information. To quote their introduction: ``This WWW information server is designed for IBM SP users, systems administrators, and other people interested in parallel programming to share information. It is a place to ask questions, seek answers, and contribute knowledge to the other people interested in the IBM SP system.''

There is a well-maintained WWW home page for PVM, PVM on Netlib, and some very useful SP training materials on the WWW site at the Cornell Theory Center (CTC). Note that the CTC was one of the first IBM SP sites and has a long-term affiliation with IBM, which contributes to their excellent support system.

See also the Frequently Asked Questions (FAQ) list for our local site .