Virtualization: an old concept in a new approach

Virtualization technology is transforming today’s IT community, offering new possi-bilities to improve the performance and efficiency of IT infrastructure by a dynamic mapping of the PC resources, enabling to run multiple applications and operating systems on a single physical system. Virtualization also offers high availability and error recovery solutions by encapsulating entire systems into single files that can be replicated and restored on any desti-nation machine. This paper brings new elements related to the concept of virtualization, presenting the princi-ples, the new architectures and the advantages of the virtualization. We make also a brief comparison between the PC’s functional structure before and after the virtualization. Finally, we present licensed software to create and run multiple virtual machines on a personal com-puter

A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing

Data Grids have been adopted as the platform for scientific communities that need to share, access, transport, process and manage large data collections distributed worldwide. They combine high-end computing technologies with high-performance networking and wide-area storage management techniques. In this paper, we discuss the key concepts behind Data Grids and compare them with other data sharing and distribution paradigms such as content delivery networks, peer-to-peer networks and distributed databases. We then provide comprehensive taxonomies that cover various aspects of architecture, data transportation, data replication and resource allocation and scheduling. Finally, we map the proposed taxonomy to various Data Grid systems not only to validate the taxonomy but also to identify areas for future exploration. Through this taxonomy, we aim to categorise existing systems to better understand their goals and their methodology. This would help evaluate their applicability for solving similar problems. This taxonomy also provides a "gap analysis" of this area through which researchers can potentially identify new issues for investigation. Finally, we hope that the proposed taxonomy and mapping also helps to provide an easy way for new practitioners to understand this complex area of research.Comment: 46 pages, 16 figures, Technical Repor

Robust data storage in a network of computer systems

PhD ThesisRobustness of data in this thesis is taken to mean reliable storage of data and also high availability of data .objects in spite of the occurrence of faults. Algorithms and data structures which can be used to provide such robustness in the presence of various disk, processor and communication network failures are described. Reliable storage of data at individual nodes in a network of computer systems is based on the use of a stable storage mechanism combined with strategies which are used to help ensure crash resis- tance of file operations in spite of the use of buffering mechan- isms by operating systems. High availability of data in the net- work is maintained by replicating data on different computers and mutual consistency between replicas is ensured in spite of network partitioning. A stable storage system which provides atomicity for more complex data structures instead of the usual fixed size page has been designed and implemented and its performance evaluated. A crash resistant file system has also been implemented and evaluated. Many of the techniques presented here are used in the design of what we call CRES (Crash-resistant, Replicated and Stable) storage. CRES storage provides fault tolerance facilities for various disk and processor faults. It also provides fault tolerance facilities for network partitioning through the provision of an algorithm for the update and merge of a partitioned data storage system

Global Grids and Software Toolkits: A Study of Four Grid Middleware Technologies

Grid is an infrastructure that involves the integrated and collaborative use of computers, networks, databases and scientific instruments owned and managed by multiple organizations. Grid applications often involve large amounts of data and/or computing resources that require secure resource sharing across organizational boundaries. This makes Grid application management and deployment a complex undertaking. Grid middlewares provide users with seamless computing ability and uniform access to resources in the heterogeneous Grid environment. Several software toolkits and systems have been developed, most of which are results of academic research projects, all over the world. This chapter will focus on four of these middlewares--UNICORE, Globus, Legion and Gridbus. It also presents our implementation of a resource broker for UNICORE as this functionality was not supported in it. A comparison of these systems on the basis of the architecture, implementation model and several other features is included.Comment: 19 pages, 10 figure

Tools for distributed application management

Distributed application management consists of monitoring and controlling an application as it executes in a distributed environment. It encompasses such activities as configuration, initialization, performance monitoring, resource scheduling, and failure response. The Meta system (a collection of tools for constructing distributed application management software) is described. Meta provides the mechanism, while the programmer specifies the policy for application management. The policy is manifested as a control program which is a soft real-time reactive program. The underlying application is instrumented with a variety of built-in and user-defined sensors and actuators. These define the interface between the control program and the application. The control program also has access to a database describing the structure of the application and the characteristics of its environment. Some of the more difficult problems for application management occur when preexisting, nondistributed programs are integrated into a distributed application for which they may not have been intended. Meta allows management functions to be retrofitted to such programs with a minimum of effort

BaseFs - Basically Acailable, Soft State, Eventually Consistent Filesystem for Cluster Management

A peer-to-peer distributed filesystem for community cloud management. https://github.com/glic3rinu/basef

FADI: a fault-tolerant environment for open distributed computing

FADI is a complete programming environment that serves the reliable execution of distributed application programs. FADI encompasses all aspects of modern fault-tolerant distributed computing. The built-in user-transparent error detection mechanism covers processor node crashes and hardware transient failures. The mechanism also integrates user-assisted error checks into the system failure model. The nucleus non-blocking checkpointing mechanism combined with a novel selective message logging technique delivers an efficient, low-overhead backup and recovery mechanism for distributed processes. FADI also provides means for remote automatic process allocation on the distributed system nodes