Experimental analysis of computer system dependability

This paper reviews an area which has evolved over the past 15 years: experimental analysis of computer system dependability. Methodologies and advances are discussed for three basic approaches used in the area: simulated fault injection, physical fault injection, and measurement-based analysis. The three approaches are suited, respectively, to dependability evaluation in the three phases of a system's life: design phase, prototype phase, and operational phase. Before the discussion of these phases, several statistical techniques used in the area are introduced. For each phase, a classification of research methods or study topics is outlined, followed by discussion of these methods or topics as well as representative studies. The statistical techniques introduced include the estimation of parameters and confidence intervals, probability distribution characterization, and several multivariate analysis methods. Importance sampling, a statistical technique used to accelerate Monte Carlo simulation, is also introduced. The discussion of simulated fault injection covers electrical-level, logic-level, and function-level fault injection methods as well as representative simulation environments such as FOCUS and DEPEND. The discussion of physical fault injection covers hardware, software, and radiation fault injection methods as well as several software and hybrid tools including FIAT, FERARI, HYBRID, and FINE. The discussion of measurement-based analysis covers measurement and data processing techniques, basic error characterization, dependency analysis, Markov reward modeling, software-dependability, and fault diagnosis. The discussion involves several important issues studies in the area, including fault models, fast simulation techniques, workload/failure dependency, correlated failures, and software fault tolerance

Capacity planning in Unix environments

Capacity Planning is a gradually recognized need in UNIX environments. However, the effort to address this problem has been more or less event driven and is often discarded after crises are over. The main cause to this situation is that the tools to support the CP function in UNIX environments are lacking so that the CP function can not be standardized and each project has to reinvent "the wheel". In this project, we investigate the current status of CP and to narrow the gap between the need and lack of tools by building a prototype to support CP in UNIX environments. In building the prototype, we use queueing network models to capture the characteristics of a system and use expert system technology to capture the expertise of GP in UNIX.. We have built a queueing network model for Sequent system and then integrated this model into the expert system of the prototype.We have also encoded some simple knowledge into the expert system. With a user-friendly interface, the prototype is able to help the user do What-if analysis. The prototype is now running on Macintosh platform with satisfactory performance and promising potentials

Performance Modeling of the PeopleSoft Multi-Tier Remote Computing Architecture

Complex client-server configurations being designed today require a new and closely coordinated approach to analytic modeling and measurement. A closed queuing network model for a two-tiered PeopleSoft 6 client-server system with an Oracle database server is demonstrated using a new performance modeling tool that applies mean value analysis. The focus of this work is on the measurement and modeling of the PeopleSoft architecture to provide useful capacity planning insights for an actual large-scale university-wide deployment. A testbed and database exerciser are then developed to measure model parameters and perform the initial validation tests. The testbed also provides preliminary test data on a proposed three-tiered deployment architecture that includes the Citrix WinFrame environment as an intermediate level between the client and the Oracle server.http://deepblue.lib.umich.edu/bitstream/2027.42/107929/1/citi-tr-97-5.pd

Proceedings of the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications

The proceedings of the National Space Science Data Center Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications held July 23 through 25, 1991 at the NASA/Goddard Space Flight Center are presented. The program includes a keynote address, invited technical papers, and selected technical presentations to provide a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include magnetic disk and tape technologies, optical disk and tape, software storage and file management systems, and experiences with the use of a large, distributed storage system. The technical presentations describe integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's

Database machines in support of very large databases

Software database management systems were developed in response to the needs of early data processing applications. Database machine research developed as a result of certain performance deficiencies of these software systems. This thesis discusses the history of database machines designed to improve the performance of database processing and focuses primarily on the Teradata DBC/1012, the only successfully marketed database machine that supports very large databases today. Also reviewed is the response of IBM to the performance needs of its database customers; this response has been in terms of improvements in both software and hardware support for database processing. In conclusion, an analysis is made of the future of database machines, in particular the DBC/1012, in light of recent IBM enhancements and its immense customer base

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

Functional requirements document for the Earth Observing System Data and Information System (EOSDIS) Scientific Computing Facilities (SCF) of the NASA/MSFC Earth Science and Applications Division, 1992

Five scientists at MSFC/ESAD have EOS SCF investigator status. Each SCF has unique tasks which require the establishment of a computing facility dedicated to accomplishing those tasks. A SCF Working Group was established at ESAD with the charter of defining the computing requirements of the individual SCFs and recommending options for meeting these requirements. The primary goal of the working group was to determine which computing needs can be satisfied using either shared resources or separate but compatible resources, and which needs require unique individual resources. The requirements investigated included CPU-intensive vector and scalar processing, visualization, data storage, connectivity, and I/O peripherals. A review of computer industry directions and a market survey of computing hardware provided information regarding important industry standards and candidate computing platforms. It was determined that the total SCF computing requirements might be most effectively met using a hierarchy consisting of shared and individual resources. This hierarchy is composed of five major system types: (1) a supercomputer class vector processor; (2) a high-end scalar multiprocessor workstation; (3) a file server; (4) a few medium- to high-end visualization workstations; and (5) several low- to medium-range personal graphics workstations. Specific recommendations for meeting the needs of each of these types are presented

Transaction behaviour in large database environments: A methodological approach

This thesis presents the CITY benchmark, a database benchmark that fairly represents On-Line Transaction Processing (OLTP) environments. It analyses the most widely used benchmarks in general putting more emphasis on the Wisconsin benchmark and the Transaction Processing Council (TPC) benchmarks (TPC-A, TPC- B and TPC-C) in particular. It also presents an empirical approach to examine the workload of those benchmarks and discovered several technical limitations in their scripts. The thesis also presents an investigation of on-line transactions in large database environments. The tested environments were three of the largest organisations in the UK, those organisations were different in objectives and activities. The investigation identified on-line transaction behaviour and defined the salient characteristics of databases in high-volume transaction environments. The findings from those studies established the basis of a transaction and set of tables that are representative of them. The CITY benchmark design is directly driven from the findings from the empirical studies. The benchmark design took into consideration all the critiques directed towards the TPC benchmarks A, B and C. It is the first benchmark that is designed as a result of studying the behaviour of on-line transactions and databases in large database environments. The CITY benchmark is mainly designed to test and compare database systems performance in high-volume transaction environments (OLTP). The work revealed the salient characteristics of large database environments and identified a typical behaviour of on-line transaction in OLTP environments. This research has clearly shown that the TPC benchmarks are not representative to the domain of high-volume transactions environments (OLTP) and it explained why they could be misleading if used to test database management systems in this domain. Additionally, this thesis presents a database performance evaluation methodology that is based on in-depth studies in large database environments

EFFICIENT LAYOUTS AND ALGORITHMS FOR MANAGING VERSIONED DATASETS

Version Control Systems were primarily designed to keep track of and provide control over changes to source code and have since provided an excellent way to combat the problem of sharing and editing files in a collaborative setting. The recent surge in data-driven decision making has resulted in a proliferation of datasets elevating them to the level of source code which in turn has led the data analysts to resort to version control systems for the purpose of storing and managing datasets and their versions over time. Unfortunately existing version control systems are poor at handling large datasets primarily due to the underlying assumption that the stored files are relatively small text files with localized changes. Moreover the algorithms used by these systems tend to be fairly simple leading to suboptimal performance when applied to large datasets. In order to address the shortcomings, a key requirement here is to have a Dataset Version Control System (DVCS) that will serve as a common platform to enable data analysts to efficiently store and query dataset versions, track changes to datasets and share datasets between users at ease. Towards this goal, we address the fundamental problem of designing storage layouts for a wide range of datasets to serve as the primary building block for an efficient and scalable DVCS. The key problem in this setting is to compactly store a large number of dataset versions and efficiently retrieve any specific version (or a collection of partial versions). We initiate our study by considering storage-retrieval trade-offs for versions of unstructured dataset such as text files, blobs, etc. where the notion of a partial version is not well-defined. Next, we consider array datasets, i.e., a collection of temporal snapshots (or versions) of multi-dimensional arrays, where the data is predominantly represented in single precision or double precision format. The primary challenge here is to develop efficient compression techniques for the hard-to-compress floating point data due to the high degree of entropy. We observe that the underlying techniques developed for unstructured or array datasets are not well suited for more structured dataset versions -- a version in this setting is defined by a collection of records each of which is uniquely addressable. We carefully explore the design space for building such a system and the various storage-retrieval trade-offs, and discuss how different storage layouts influence those trade-offs. Next, we formulate several problems trading off the version storage and retrieval cost in various ways and design several offline storage layout algorithms that effectively minimize the storage costs while keeping the retrieval costs low. In addition to version retrieval queries, our system also provides support for record provenance queries. Through extensive experiments on large datasets, we demonstrate that our proposed designs can operate at the scale required in most practical scenarios