Fifth NASA Goddard Conference on Mass Storage Systems and Technologies

This document contains copies of those technical papers received in time for publication prior to the Fifth Goddard Conference on Mass Storage Systems and Technologies held September 17 - 19, 1996, at the University of Maryland, University Conference Center in College Park, Maryland. As one of an ongoing series, this conference continues to serve as a unique medium for the exchange of information on topics relating to the ingestion and management of substantial amounts of data and the attendant problems involved. This year's discussion topics include storage architecture, database management, data distribution, file system performance and modeling, and optical recording technology. There will also be a paper on Application Programming Interfaces (API) for a Physical Volume Repository (PVR) defined in Version 5 of the Institute of Electrical and Electronics Engineers (IEEE) Reference Model (RM). In addition, there are papers on specific archives and storage products

The Challenges Facing Science Data Archiving on Current Mass Storage Systems

This paper discusses the desired characteristics of a tape-based petabyte science data archive and retrieval system required to store and distribute several terabytes (TB) of data per day over an extended period of time, probably more than 115 years, in support of programs such as the Earth Observing System Data and Information System (EOSDIS). These characteristics take into consideration not only cost effective and affordable storage capacity, but also rapid access to selected files, and reading rates that are needed to satisfy thousands of retrieval transactions per day. It seems that where rapid random access to files is not crucial, the tape medium, magnetic or optical, continues to offer cost effective data storage and retrieval solutions, and is likely to do so for many years to come. However, in environments like EOS these tape based archive solutions provide less than full user satisfaction. Therefore, the objective of this paper is to describe the performance and operational enhancements that need to be made to the current tape based archival systems in order to achieve greater acceptance by the EOS and similar user communities

Performance Benchmark Results For Automated Tape Library High Retrieval Rate Applications-Digital Check Image Retrievals-

Abstract Benchmark tests have been designed and conducted for the purpose of evaluating the use of automated tape libraries in on-line digital check image retrieval applications. This type of application is representative of digital library applications requiring service to multiple concurrent users with service request response time identified as a very important metric. The benchmark test design was guided by a simplified theoretical queuing performance model developed to predict average response time as a function of request rate, object size retrieved, hardware characteristics, and library configuration. An exponential interarrival time distribution was used to simulate the multiple user environment, thus corresponding to an M/Ek/c queue. A series of nine benchmark test runs, each consisting of nominally 1000 retrievals, was conducted for average request rates of 50, 100, 150, 200, and 250 requests per hour and for library configurations varying from two to six drives. The resulting experimental response time distributions were analyzed by fitting the data to a Shifted Erlang distribution function and also by determining the time for which the response corresponded to cumulative percentiles ranging from 10% to 95%. Good agreement was obtained between the modelled and experimentally determined average response time. For the hardware and software systems used in these tests, an average response time of approximately 30 seconds has been achieved under conditions of Poisson arrivals at average rates up to approximately 150 requests per hour. The use of timing trace data has identified the potential for further response time improvements

Center of Excellence in Space Data and Information Science, Year 9

This report summarizes the range of computer science related activities undertaken by CESDIS(Center of Excellence in Space Data and Information Sciences) for NASA in the twelve months from July 1, 1996 through June 30, 1997. These activities address issues related to accessing, processing, and analyzing data from space observing systems through collaborative efforts with university, industry, and NASA space and Earth scientists

Sixth Goddard Conference on Mass Storage Systems and Technologies Held in Cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems

This document contains copies of those technical papers received in time for publication prior to the Sixth Goddard Conference on Mass Storage Systems and Technologies which is being held in cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems at the University of Maryland-University College Inn and Conference Center March 23-26, 1998. As one of an ongoing series, this Conference continues to provide a forum for discussion of issues relevant to the management of large volumes of data. The Conference encourages all interested organizations to discuss long term mass storage requirements and experiences in fielding solutions. Emphasis is on current and future practical solutions addressing issues in data management, storage systems and media, data acquisition, long term retention of data, and data distribution. This year's discussion topics include architecture, tape optimization, new technology, performance, standards, site reports, vendor solutions. Tutorials will be available on shared file systems, file system backups, data mining, and the dynamics of obsolescence

Granite: A scientific database model and implementation

The principal goal of this research was to develop a formal comprehensive model for representing highly complex scientific data. An effective model should provide a conceptually uniform way to represent data and it should serve as a framework for the implementation of an efficient and easy-to-use software environment that implements the model. The dissertation work presented here describes such a model and its contributions to the field of scientific databases. In particular, the Granite model encompasses a wide variety of datatypes used across many disciplines of science and engineering today. It is unique in that it defines dataset geometry and topology as separate conceptual components of a scientific dataset. We provide a novel classification of geometries and topologies that has important practical implications for a scientific database implementation. The Granite model also offers integrated support for multiresolution and adaptive resolution data. Many of these ideas have been addressed by others, but no one has tried to bring them all together in a single comprehensive model. The datasource portion of the Granite model offers several further contributions. In addition to providing a convenient conceptual view of rectilinear data, it also supports multisource data. Data can be taken from various sources and combined into a unified view. The rod storage model is an abstraction for file storage that has proven an effective platform upon which to develop efficient access to storage. Our spatial prefetching technique is built upon the rod storage model, and demonstrates very significant improvement in access to scientific datasets, and also allows machines to access data that is far too large to fit in main memory. These improvements bring the extremely large datasets now being generated in many scientific fields into the realm of tractability for the ordinary researcher. We validated the feasibility and viability of the model by implementing a significant portion of it in the Granite system. Extensive performance evaluations of the implementation indicate that the features of the model can be provided in a user-friendly manner with an efficiency that is competitive with more ad hoc systems and more specialized application specific solutions

DEFINING DIGITAL PRESERVATION WORK: A CASE STUDY OF THE DEVELOPMENT OF THE REFERENCE MODEL FOR AN OPEN ARCHIVAL INFORMATION SYSTEM

I report on a multi-method case study of the development of a standard called the Reference Model for an Open Archival Information System (OAIS), which describes components and services required to develop and maintain archives in order to support long-term access and understanding of the information in those archives. The development of the OAIS took place within a standards development organization called the Consultative Committee for Space Data Systems (CCSDS), whose formal purview is the work of space agencies, but the effort reached far beyond the traditional CCSDS interests and stakeholders. It has become a fundamental component of digital archive research and development in a variety of disciplines and sectors. Through document analysis, social network analysis and qualitative analysis of interview data, I explain how and why the OAIS development effort, which took place within a space data standards body, was transformed into a standard of much wider scope, relevant to a diverse set of actors. The OAIS development process involved substantial enrollment of resources from the environment, including skills and expertise; social ties; documentary artifacts; structures and routines; physical facilities and proximity; and funding streams. Enrollment from the environment did not occur automatically. It was based on concerted efforts by actors who searched for relevant literature, framed the process as open, and promoted it at professional events. Their acts of participation also helped to enroll resources, contributing to what structuration theory calls the signification and legitimation of the Reference Model, i.e. enactment of what the document means, and why and to whom it is important. Documentary artifacts were most successfully incorporated into the OAIS when they were perceived to support modularity and to be at an appropriate level of abstraction. The content of the Reference Model was subject to stabilization over time, making changes less likely and more limited in scope. A major factor in the success of the OAIS was the timing of its development. Actors within several streams of activity related to digital preservation perceived the need for a highlevel model but had not themselves developed one. At the same time, several actors now felt they had knowledge from their own recent digital archiving efforts, which could inform the development of the OAIS. This study has important implications for research on standardization, and it provides many lessons for those engaged in future standards development efforts.Ph.D.InformationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/39372/2/dissertation_callee.pd