Excerpt from



Simulation, September 2000


John McLeod Technical Editor                           Suzette McLeod Managing Editor


Power (?) Grid!                                                      Mission Earth (M/E)


As readers may have noticed, this writer has been interested in the desirability/possibility of someone, or some agency, developing a global communication network since my first discussing the matter with Tak Utsumi in 1972. At the time Tak and I were both primarily interested in the use of such a network for the distributed simulation of "Peace Gaming," as contrasted with the war games so widely used by the military of all countries. However, my early enthusiasm had to be redirected from personally contributing to such an undertaking when I realized the enormity of the technical problems. But Tak has persevered and has successfully demonstrated many components of a necessary infrastructure.


                  Tak and his colleagues have had to raise funds from any sources that they could, as well as pushing back the technical frontiers. But recently several powerful publicly funded organizations have entered the picture. NASA of course has a worldwide communication network which is necessary in support of its space program. However, I understand--perhaps mistakenly--that it is to be made available commercially. More on that when I learn more.


                  And now we have the following article describing a communication network which it seems to me is misnamed, and I wonder how many others, think of a power grid as a network for the distribution of electrical power. Be that as it may, the description seems to be that of an information network, and the list of participants seems to indicate that it is supported largely by the National Science Foundation. ‑JM


Building an Information Power Grid


Some NASA scientists use satellite data to learn about the Earth, while others study the cosmos from space. Both types of projects are data‑intensive, with data coming from satellites, telescopes, and other instruments. However, data are often stored in one location, such as the Goddard Space Flight Center in Maryland, but processed at another, such as the Ames Research Center in California. Consequently, NASA requires an intelligent data‑handling system to identify and store data based on discipline‑specific attributes, and to access and supply the correct data to applications that need it. Researchers from NPACI (National Partnership for Advanced Computational Infrastructure) in partnership with scientists from the National Computational Science Alliance, have lent their experience to help build the NASA Information Power Grid (IPG), a system to acquire, move, and process data from and on far‑flung resources.


Grid Computing


"NASA scientists are developing next‑generation technologies predicated on the services and resources available in the IPG," said William Johnston, manager of the project within NASA Ames. "The hardier the infrastructure, the more innovative and useful the NASA applications can be."


                  Underlying IPG is a computational grid anchored by Globus, led by Carl Kesselman of the University of Southern California and Ian Foster of the University of Chicago and Argonne National Laboratory. To promote interoperability between grid environments and to minimize costs, the Legion project, headed by Andrew Grimshaw of the University of Virginia, is incorporating services from the Globus environment--for example, authentication support through the Grid Security Infrastructure (GSI).


                  The grid infrastructure also allows an application to use both NPACI and Alliance resources, regardless of their physical location.


                  Cluster computing is an emerging technology for supporting scientific applications. In a collaboration headed by Andrew Chien of the University of California /San Diego (UCSD), the grid technologies are being adapted to interface with an NT cluster at UCSD and a Linux cluster at the University of Michigan.


                  To provide user‑level middleware for the IPG, application‑level schedulers (AppLeS) are being developed for parameter sweep applications, a common application class for NASA. The AppLeS parameter sweep template (APST), being developed by Fran Berman and AppLeS Project Scientist Henri Casanova at UCSD, will help NASA researchers conduct large‑scale simulations on the IPG.


                  Also on the IPG, the Network Weather Service (NWS), developed by Rich Wolski at the University of Tennessee, takes the pulse of the shared, heterogeneous network links. The NWS monitors and predicts network load and availability and can be used by any IPG user. The NWS can provide an additional Globus service and provides a useful system predictor for AppLeS schedulers.


Information Discovery


Of course applications require data. To manage data movement between stored data and applications, the San Diego Supercomputer Center researchers participating in the Data‑Intensive Computing Environments thrust area, led by SDSC Associate Director Reagan Moore, are developing components of the grid's data-handling system. The SDSC Storage Resource Broker (SRB), which has been deployed at NPACI sites and NASA Ames, supports collection‑based access to data across distributed storage systems.


                  When an application requires data, the SDSC SRB queries its Metadata Catalog to discover the correct data set, and then supports UNIX‑style read and write operations on the data, wherever located. Once a computation has been completed, the SDSC SRB can be used to publish the new data into a collection, for use by other researchers. The SDSC SRB has also been integrated with the GSI for authentication of users.


                  The NASA IPG project recently completed a set of demonstrations that met some NASA level‑one milestones. Global hydrology data for one demonstration came from a satellite that completes 14 Earth orbits a day, acquiring in each orbit six data sets that must be stored and processed. A subset of this data was distributed across four sites--California Institute of Technology, SDSC, Washington University in St. Louis, and NASA Ames. The IPG then supported data mining on hundreds of data sets from this collection through the SDSC SRB.


                  Another IPG demonstration was staged in the NPACI booth at SC99 in Portland, Oregon. The SDSC SRB moved gigabyte‑sized data sets between SDSC and Portland in 25 seconds. The transfer across the vBNS, reached a top rate of 39.7 MB per second by striping the transfer over four I/O channels. The bandwidth was limited by the 40‑MBps backplane speed of the server used to read the remote data.


                  Throughout 2000, work will continue on three key elements of the IPG project: enhancing the Globus infrastructure; enhancing the data‑intensive and security infrastructure; and conducting research to increase the usability and performance of the IPG for NASA applications.


                  "Since our work with IPG builds on the work we're undertaking for NPACI," Reagan Moore said, "the whole project is good for both NASA scientists and NPACI researchers."


                  Participants in the grid computing project included the following:


Fran Berman and Andrew Chien, University of California/ San Diego


Ian Foster, University of Chicago, Argonne National Laboratory


Andrew Grimshaw, University of Virginia


William Johnston, NASA Ames Research Center, Lawrence Berkeley National Laboratory


Carl Kesselman, University of Southern California


Reagan Moore, San Diego Supercomputer Center


Rich Wolski, University of Tennessee


The foregoing is our slightly edited version of an article which appeared in the April‑June 2000 issue of en Vision, quarterly science magazine of NPACI and SDSC.


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