Architectural Tradeoffs for Unifying Campus Grid Resources

Most universities have a powerful collection of computing resources on campus for use in areas from high performance computing to general access student labs. However, these resources are rarely used to their full potential. Grid computing offers a way to unify these resources and to better utilize the capability they provide. The complexity of some grid tools makes learning to use them a daunting task for users not familiar with using the command line. Combining these tools together into a single web portal interface provides campus faculty and students with an easy way to access the campus resources. This paper presents some of the grid and portal tools that are currently available and tradeoffs in their selection and use. The successful implementation of a subset of these tools at the University of Arkansas and the functionality they provide are discussed in detail

Evaluation of Real-Time Fiber Communications for Parallel Collective Operations

Real-Time Fiber Communications (RTFC) is a gigabit speed network that has been designed for damage tolerant local area networks. In addition to its damage tolerant characteristics, it has several features that make it attractive as a possible interconnection technology for parallel applications in a cluster of workstations. These characteristics include support for broadcast and multicast messaging, memory cache in the network interface card, and support for very fine grain writes to the network cache. Broadcast data is captured in network cache of all workstations in the network providing a distributed shared memory capability. In this paper, RTFC is introduced. The performance of standard MPI collective communications using TCP protocols over RTFC are evaluated and compared experimentally with that of Fast Ethernet. It is found that the MPI message passing libraries over traditional TCP protocols over RTFC perform well with respect to Fast Ethernet. Also, a new approach that uses direct network cache movement of buffers for collective operations is evaluated. It is found that execution time for parallel collective communications may be improved via effective use of network cache

The Circulating Processor Model of Parallel Systems

This paper introduces the circulating processor model for parallel computer systems. The circulating processor model is a product form queuing network model where the processors are allowed to circulate between the parallel applications instead of the more traditional circulating task model. Certain behaviors of parallel systems are better captured using this new approach. The circulating processor model may be load dependent or load dependent. The load dependent circulating processor model is exact for systems which contain a single parallel application. An exact error is calculated for the load independent circulating processor model for systems which contain a single parallel application. The load dependent circulating processor model is a good approximation to the actual system in the case of multiple parallel applications. The load dependent circulating processor model compares favorably to the traditional circulating task model

Shibboleth as a Tool for Authorized Access Control to the Subversion Repository System

Shibboleth is an architecture and protocol for allowing users to authenticate and be authorized to use a remote resource by logging into the identity management system that is maintained at their home institution. With Shibboleth, a federation of institutions can share resources among users and yet allow the administration of both the user access control to resources and the user identity and attribute information to be performed at the hosting or home institution. Subversion is a version control repository system that allows the creation of fine-grained permissions to files and directories. In this project an infrastructure, Shibbolized Subversion, has been created that consists of a Subversion repository with an Apache web interface that is protected by a Shibboleth authentication system. The infrastructure can allow authorized and authenticated data sharing between institutions yet retains simplicity and protects privacy for users. In addition, it also relieves local administrators from the task of having to perform extra account management for users from other institutions. This paper describes the Shibboleth and Subversion systems, the implementation of the file sharing infrastructure, and issues of attribute maintenance, privacy and security

Shibboleth as a Tool for Authorized Access Control to the Subversion Repository System

Shibboleth is an architecture and protocol for allowing users to authenticate and be authorized to use a remote resource by logging into the identity management system that is maintained at their home institution. With Shibboleth, a federation of institutions can share resources among users and yet allow the administration of both the user access control to resources and the user identity and attribute information to be performed at the hosting or home institution. Subversion is a version control repository system that allows the creation of fine-grained permissions to files and directories. In this project an infrastructure, Shibbolized Subversion, has been created that consists of a Subversion repository with an Apache web interface that is protected by a Shibboleth authentication system. The infrastructure can allow authorized and authenticated data sharing between institutions yet retains simplicity and protects privacy for users. In addition, it also relieves local administrators from the task of having to perform extra account management for users from other institutions. This paper describes the Shibboleth and Subversion systems, the implementation of the file sharing infrastructure, and issues of attribute maintenance, privacy and security

Community Funding Models for Computational Resources

As scientific research has extended far beyond the practicality and abilities of laboratory experiments, computational simulations have become the mainstay of enabling and furthering the research in a way never previously thought possible. It is becoming commonplace to model and simulate both the very large, such as black hole collisions in astrophysics, and the very small, such as subatomic particle behavior and interaction in high energy physics. In addition to the previous examples detailing extremes, practically every area of research currently utilizes and benefits from computational resources to simulate their work; financial modeling, weather forecasting, geological phenomena, geo-spatial data analysis, gene sequencing...the list is practically without end. Until recently, many researchers have had compute clusters in closets for which they must devote time and money for its housing and management. Many institutions are gradually adopting central research or high performance computing centers to reduce the overall cost to the university and researchers in deploying and maintaining research computing resources. These centers also help the university attract more computational researchers as well as garner more external funding by demonstrating their commitment to providing these facilities. While it would not be difficult to argue the worth of computational resources in the realm of academic research, a common sustainable funding model for such resources is strangely absent from the overall picture. One such model that is becoming a frequent topic of discussion in academic circles is the condominium model

A Performance and Productivity Study using MPI, Titanium, and Fortress

The popularity of cluster computing has increased focus on usability, especially in the area of programmability. Languages and libraries that require explicit message passing have been the standard. New languages, designed for cluster computing, are coming to the forefront as a way to simplify parallel programming. Titanium and Fortress are examples of this new class of programming paradigms. This papers presents results from a productivity study of these two newcomers with MPI, the de- facto standard for parallel programming