Assessing
Legion as Grid Middleware
Legion
is an object-oriented software system that simplifies and systemizes
access to grids of distributed computing resources. Using large
distributed computational fluid dynamics simulations as benchmarks,
NAS researchers are comparing Legion’s performance in the
Information Power Grid environment with that of the Globus metacomputing
toolkit.
Distributed
CFD Using Globus
Researchers
at NAS are attempting to run parallel, high-fidelity, three-dimensional
computational fluid dynamics simulations on the distributed Information
Power Grid computing network with as few changes to the code as
possible. The Globus metacomputing toolkit is used to execute
the code, and the researchers have devised a deferred timestep
method that allows the overlapping of computation and communication,
potentially increasing the speed of the simulation. In 1998, airflow
around the X-38 Crew Return Vehicle was simulated using the CFD
code OVERFLOW-D2 running concurrently on two SGI Origin 2000 computers
at the NAS Facility and Argonne National Laboratory. A similar,
but larger-scale computation was carried out in 1999 using SGI
Origin 2000 computers at three geographically separated sites.
Globus
Documentation
NAS
technical writers have produced the Globus
Quick Start Guide (32-page 152K PDF) (To read this files you will
need the free Adobe
Acrobat Reader, The Globus Quick Start Guide is a brief introduction
to using Globus software tools as a foundation for running jobs on the
Information Power Grid. Among other things, the guide teaches users how
to obtain Globus security certificates and how to run simple Globus jobs.
As of this writing, no other in-print documentation is available. Collaborating
with NAS on the documentation project are personnel at the National Center
for Supercomputing Applications and the National Laboratory for Applied
Network Research.
Globus
Usability Studies
Under
Globus 1.1, IPG users access the Globus metacomputing toolkit
through an arcane set of command-line scripts and options (in
the form of the Resource Specification Language, or RSL) that
must be entered manually. The goal of Globus usability studies
at NAS is to develop a graphical user interface that simplifies
and automates the creation and submission of Globus scripts and
RSLs. The GUI will eventually be adapted to work with batch queuing
systems such as PBS, to speed the Globus authentication procedure,
and to make data staging and job control nearly transparent to
the user. This work is being carried out in collaboration with
the Globus project at Argonee National Laboratory.
Grid
Co-scheduling
To
use supercomputing resources at different sites at the same time, researchers
need a system for co-scheduling and advance reservations. Staff working on
the grid scheduling task at NAS are attacking this problem by deploying a
full prototype advance reservation system across the NASA Information Power
Grid network, currently running at Ames, Glenn, and Langley Research Centers.
NAS is also working with the the Grid Forum to define standards for grid scheduling
and resource management. Advanced grid scheduling capabilities will allow
hardware owners to better manage their resources and will allow Grid users
to better specify their priorities (for example, "lowest cost" or "overnight
turnaround time.") This work is being carried out in collaboration with Argonne
National Laboratory and the Information Sciences Institute at the University
of Southern California.
Portable
Batch System
The
Portable Batch System (PBS) is a
batch queuing system developed at NAS to span all of the Facility’s
vector and parallel computers. Today, PBS is one core component
of the Information Power Grid’s "middleware" layer, the set
of tools that handle communication between heterogeneous, geographically
distributed computing systems. NAS researchers are adapting the
system to allow advance reservations of remote resources and to
provide an easy-to-use interface to the Globus suite of distributed
computing tools. In one of the NAS Systems Division’s best
recent example of technology transfer, PBS is now being marketed
commercially by Veridian Group, Mountain View, CA.
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