Rapid advances in high performance computing are making possible more complete and accurate computer-based modeling of complex physical phenomena, such as weather front interactions, dynamics of chemical reactions, numerical aerodynamic analysis of airframes, and ocean-land-atmosphere interactions. Many of these 'grand challenge' applications are as demanding of the underlying storage system, in terms of their capacity and bandwidth requirements, as they are on the computational power of the processor. A global view of the Earth's ocean chlorophyll and land vegetation requires over 2 terabytes of raw satellite image data. In this paper, we describe our planned research program in high capacity, high bandwidth storage systems. The project has four overall goals. First, we will examine new methods for high capacity storage systems, made possible by low cost, small form factor magnetic and optical tape systems. Second, access to the storage system will be low latency and high bandwidth. To achieve this, we must interleave data transfer at all levels of the storage system, including devices, controllers, servers, and communications links. Latency will be reduced by extensive caching throughout the storage hierarchy. Third, we will provide effective management of a storage hierarchy, extending the techniques already developed for the Log Structured File System. Finally, we will construct a protototype high capacity file server, suitable for use on the National Research and Education Network (NREN). Such research must be a Cornerstone of any coherent program in high performance computing and communications. Katz, Randy H. and Anderson, Thomas E. and Ousterhout, John K. and Patterson, David A. Unspecified Center NAG2-591...

A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)

Abstract: "Scientific computation has always been one of the driving forces behind the design of computer systems. As a result, many advances in CPU architecture were first developed for high-speed supercomputer systems, keeping them among the fastest computers in the world. However, little research has been done in storing the vast quantities of data that scientists manipulate on these powerful computers. This thesis first characterizes scientists' usage of a multi-terabyte tertiary storage system attached to a high-speed computer. The analysis finds that the number of files and average file size have both increased by several orders of magnitude since 1980. The study also finds that integration of tertiary storage with secondary storage is critical. Many of the accesses to files stored on tape could have easily been avoided had scientists seen a unified view of the mass storage hierarchy instead of the two separate views of the system studied. This finding was a major motivation of the design of the RAMA file system. The remainder of the thesis describes the design and simulation of a massively parallel processor (MPP) file system that is simple, easy to use, and integrates well with tertiary storage. MPPs are increasingly commonly used for scientific computation, yet their file systems require great attention to detail to get acceptable performance. Worse, a program that performs well on one machine may perform poorly on a similar machine with a slightly different file system. RAMA solves this problem by pseudo-randomly distributing data to a disk attached to each processor, making performance independent of program usage patterns. It does this without sacrificing the high performance that scientific users demand, as shown by simulations comparing the performance of RAMA and a striped file system on both real and synthetic benchmarks. Additionally, RAMA can be easily integrated with tertiary storage systems, providing a unified view of the file system spanning both disk and tape systems. RAMA's ease of use and simplicity of design make it an ideal choice for the massively parallel computers used by the scientific community."

GIS and Environmental Modeling: Progress and Research Issues Michael F. Goodchild, Louis T. Steyaert, Bradley O. Parks, Carol Johnston, David Maidment, Michael Crane, and Sandi Glendinning, Editors With growing pressure on natural resources and landscapes there is an increasing need to predict the consequences of any changes to the environment. Modelling plays an important role in this by helping our understanding of the environment and by forecasting likely impacts. In recent years moves have been made to link models to Geographical Information Systems to provide a means of analysing changes over an area as well as over time. GIS and Environmental Modeling explores the progress made to date in integrating these two software systems. Approaches to the subject are made from theoretical, technical as well as data stand points. The existing capabilities of current systems are described along with important issues of data availability, accuracy and error. Various case studies illustrate this and highlight the common concepts and issues that exist between researchers in different environmental fields. The future needs and prospects for integrating GIS and environmental models are also explored with developments in both data handling and modelling discussed. The book brings together the knowledge and experience of over 100 researchers from academic, commercial and government backgrounds who work in a wide range of disciplines. The themes followed in the text provide a fund of knowledge and guidance for those involved in environmental modelling and GIS. The book is easily accessible for readers with a basic GIS knowledge and the ideas and results of the research are clearly illustrated with both colour and black and white graphics.