Decentralized Access Control in Distributed File Systems

The Internet enables global sharing of data across organizational boundaries. Distributed file systems facilitate data sharing in the form of remote file access. However, traditional access control mechanisms used in distributed file systems are intended for machines under common administrative control, and rely on maintaining a centralized database of user identities. They fail to scale to a large user base distributed across multiple organizations. We provide a survey of decentralized access control mechanisms in distributed file systems intended for large scale, in both administrative domains and users. We identify essential properties of such access control mechanisms. We analyze both popular production and experimental distributed file systems in the context of our survey

Decentralized Access Control in Networked File Systems

The Internet enables global sharing of data across organizational boundaries. Traditional access control mechanisms are intended for one or a small number of machines under common administrative control, and rely on maintaining a centralized database of user identities. They fail to scale to a large user base distributed across multiple organizations. This survey provides a taxonomy of decentralized access control mechanisms intended for large scale, in both administrative domains and users. We identify essential properties of such access control mechanisms. We analyze popular networked file systems in the context of our taxonomy

Survivable software distribution and maintenance

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaves 79-82).by Jeff Breidenbach.Ph.D

The File System Interface is an Anachronism

Contemporary file systems implement a set of abstractions and semantics that are suboptimal for many (if not most) purposes. The philosophy of using the simple mechanisms of the file system as the basis for a vast array of higher-level mechanisms leads to inefficient and incorrect implementations. We propose several extensions to the canonical file system model, including explicit support for lock files, indexed files, and resource forks, and the benefit of session semantics for write updates. We also discuss the desirability of application-level file system transactions and file system support for versioning.Engineering and Applied Science

Separating Web Applications from User Data Storage with BSTORE

URL to paper from conference siteThis paper presents BSTORE, a framework that allows developers to separate their web application code from user data storage. With BSTORE, storage providers implement a standard file system API, and applications access user data through that same API without having to worry about where the data might be stored. A file system manager allows the user and applications to combine multiple file systems into a single namespace, and to control what data each application can access. One key idea in BSTORE’s design is the use of tags on files, which allows applications both to organize data in different ways, and to delegate fine-grained access to other applications. We have implemented a prototype of BSTORE in Javascript that runs in unmodified Firefox and Chrome browsers. We also implemented three file systems and ported three different applications to BSTORE. Our prototype incurs an acceptable performance overhead of less than 5% on a 10Mbps network connection, and porting existing clientside applications to BSTORE required small amounts of source code changes.Quanta Computer (Firm)Google (Firm

Optimización de clusters como plataformas multimedia utilizando clientes predictivios multihilo

En esta tesis doctoral se pretende hacer un estudio de los problemas principales de los clusters de computadoras utilizando aplicaciones multimedia. Enfrentamos las dos partes, arquitectura y aplicaciones y, además, lo hacemos de una forma "real", sin simulaciones. Se va a partir de una plataforma real, formada por un cluster de alta velocidad, y de una aplicación multimedia totalmente flexible como para emular el patrón de tráfico de otras. Esta aplicación va a inyectar la carga multimedia al cluster y va a exigir unos requisitos particulares. El gran reto actual de los cluster es la entrada/salida de alto rendimiento, ya que la computación de alto rendimiento está conseguida. Expondremos los principales problemas y daremos una solución que mejore los resultados obtenidos inicialmente. En entrada/salida existen numerosos e interesantes trabajos. Todos han intentado aportar alguna novedad, con el propósito de mejorar algún punto negro de la entrada/salida. En nuestro trabajo se ha hecho un estudio exhaustivo de todos esos trabajos con el fin de plantear un nuevo método híbrido de adelantamiento de datos para arquitecturas cliente-servidor, en uno de los sistemas de ficheros en red más utilizado actualmente, NFS (Network Fle System) . Pero no solo va a ser un planteamiento algorítmico y teórico, sino que se va a implementar en el mismo núcleo del sistema operativo, donde NFS aparece como modulo, y se realizaran los experimentos para confirmar las mejoras de la implementación desarrollada. Inicialmente, nos planteamos la posibilidad de cambiar la forma de trabajar del servidor, pero después realizamos el traslado al cliente, mucho más manejable y abierto a mejoras de este tipo. Planteamos el diseño de la técnica hibrida de prefetching, una técnica basada en grafos de acceso, con el propósito de adelantar datos no solo del fichero actual que se está leyendo (que eso ya se hacía) sino, también, a través de distintos ficheros. Presentamos también los resultados con este nuevo cliente predictivo y obtenemos una importante reducción en los tiempos de lectura, y unos valores importantes en la ganancia conseguida. Por lo tanto, queda demostrada la utilidad de técnicas e este tipo para el sistema NFS

Using khazana to support distributed application development

technical reportOne of the most important services required by most distributed applications is some form of shared data management, e.g., a directory service manages shared directory entries while groupware manages shared documents. Each such application currently must implement its own data management mechanisms, because existing runtime systems are not flexible enough to support all distributed applications efficiently. For example, groupware can be efficiently supported by a distributed object system, while a distributed database would prefer a more low-level storage abstraction. The goal of Khazana is to provide programmer's with configurable components that support the data management services required by a wide variety of distributed applications, including: consistent caching, automated replication and migration of data, persistence, access control, and fault tolerance. It does so via a carefully designed set of interfaces that supports a hierarchy of data abstractions, ranging from flat data to C++/Java objects, and that give programmers a great of control over how their data is managed. To demonstrate the effectiveness of our design, we report on our experience porting three applications to Khazana: a distributed file system, a distributed directory service, and a shared whiteboard

New approaches to data access in large-scale distributed system

Mención Internacional en el título de doctorA great number of scientific projects need supercomputing resources, such as, for example, those carried out in physics, astrophysics, chemistry, pharmacology, etc. Most of them generate, as well, a great amount of data; for example, a some minutes long experiment in a particle accelerator generates several terabytes of data. In the last years, high-performance computing environments have evolved towards large-scale distributed systems such as Grids, Clouds, and Volunteer Computing environments. Managing a great volume of data in these environments means an added huge problem since the data have to travel from one site to another through the internet. In this work a novel generic I/O architecture for large-scale distributed systems used for high-performance and high-throughput computing will be proposed. This solution is based on applying parallel I/O techniques to remote data access. Novel replication and data search schemes will also be proposed; schemes that, combined with the above techniques, will allow to improve the performance of those applications that execute in these environments. In addition, it will be proposed to develop simulation tools that allow to test these and other ideas without needing to use real platforms due to their technical and logistic limitations. An initial prototype of this solution has been evaluated and the results show a noteworthy improvement regarding to data access compared to existing solutions.Un gran número de proyectos científicos necesitan recursos de supercomputación como, por ejemplo, los llevados a cabo en física, astrofísica, química, farmacología, etc. Muchos de ellos generan, además, una gran cantidad de datos; por ejemplo, un experimento de unos minutos de duración en un acelerador de partículas genera varios terabytes de datos. Los entornos de computación de altas prestaciones han evolucionado en los últimos años hacia sistemas distribuidos a gran escala tales como Grids, Clouds y entornos de computación voluntaria. En estos entornos gestionar un gran volumen de datos supone un problema añadido de importantes dimensiones ya que los datos tienen que viajar de un sitio a otro a través de internet. En este trabajo se propondrá una nueva arquitectura de E/S genérica para sistemas distribuidos a gran escala usados para cómputo de altas prestaciones y de alta productividad. Esta solución se basa en la aplicación de técnicas de E/S paralela al acceso remoto a los datos. Así mismo, se estudiarán y propondrán nuevos esquemas de replicación y búsqueda de datos que, en combinación con las técnicas anteriores, permitan mejorar las prestaciones de aquellas aplicaciones que ejecuten en este tipo de entornos. También se propone desarrollar herramientas de simulación que permitan probar estas y otras ideas sin necesidad de recurrir a una plataforma real debido a las limitaciones técnicas y logísticas que ello supone. Se ha evaluado un prototipo inicial de esta solución y los resultados muestran una mejora significativa en el acceso a los datos sobre las soluciones existentes.Programa Oficial de Doctorado en Ciencia y Tecnología InformáticaPresidente: David Expósito Singh.- Secretario: María de los Santos Pérez Hernández.- Vocal: Juan Manuel Tirado Mart