As Linux clusters have matured as platforms for lowcost, high-performance parallel computing, software packages to provide many key services have emerged, especially in areas such as message passing and networking. One area devoid of support, however, has been parallel file systems, which are critical for highperformance I/O on such clusters. We have developed a parallel file system for Linux clusters, called the Parallel Virtual File System (PVFS). PVFS is intended both as a high-performance parallel file system that anyone can download and use and as a tool for pursuing further research in parallel I/O and parallel file systems for Linux clusters. In this paper, we describe the design and implementation of PVFS and present performance results on the Chiba City cluster at Argonne. We provide performance results for a workload of concurrent reads and writes for various numbers of compute nodes, I/O nodes, and I/O request sizes. We also present performance results for MPI-IO on PVFS, b...

Ubiquitous computing poses a number of challenges for software architecture.

In wide area computing systems, it is often desirable to create remote read-only copies (replicas) of files. Replication can be used to reduce access latency, improve data locality, and/or increase robustness, scalability and performance for distributed applications. We define a replica location service (RLS) as a system that maintains and provides access to information about the physical locations of copies. An RLS typically functions as one component of a data grid architecture. This paper makes the following contributions. First, we characterize RLS requirements. Next, we describe a parameterized architectural framework, which we name Giggle (for GIGa-scale Global Location Engine), within which a wide range of RLSs can be defined. We define several concrete instantiations of this framework with different performance characteristics. Finally, we present initial performance results for an RLS prototype, demonstrating that RLS systems can be constructed that meet performance goals.

zFS is a research project aimed at building a decentralized file system that distributes all aspects of file and storage management over a set of cooperating machines interconnected by a high-speed network. zFS is designed to be a file system that scales from a few networked computers to several thousand machines and to be built from commodity off-the-shelf components. The two most prominent features of zFS are its cooperative cache and distributed transactions. zFS integrates the memory of all participating machines into one coherent cache. Thus, instead of going to the disk for a block of data already in one of the machine memories, zFS retrieves the data block from the remote machine. zFS also uses distributed transactions and leases, instead of groupcommunication and clustering software. This article describes the zFS high-level architecture and how its goals are achieved. 1.

Small mobile computers are now sufficiently powerful to run many applications, but storage capacity remains limited so working files cannot be cached or stored locally. Even if files can be stored locally, the mobile device is not powerful enough to act as server in collaborations with other users. Conventional distributed file systems cache everything locally or not at all; there is no possibility to cache files on nearby nodes. In this paper we present the design of a secure cache system called CryptoCache that allows roaming users to cache files on untrusted file hosting servers. The system allows flexible sharing of cached files among unauthenticated users, i.e. unlike most distributed file systems CryptoCache does not require a global authentication framework. Files are encrypted when they are transferred over the network and while stored on untrusted servers. The system uses public key cryptography, which allows roaming users to selectively grant read and write access to ot...

This paper addresses a bottleneck problem in mobile file systems: the propagation of updated large files from a weakly-connected client to its servers. It proposes an efficient mechanism called operation shipping or operation-based update propagation.In the new mechanism, the client ships the user operation that updated the large files, rather than the files themselves, across the weak network. (In contrast, existing file systems use value shipping and ship the files.) The user operation is sent to a surrogate client that is strongly connected to the servers. The surrogate replays the user operation, regenerates the files, checks whether they are identical to the originals, and, if so, sends the files to the servers on behalf of the client. Care has been taken such that the new mechanism does not compromise correctness or server scalability. For example, we show how forward error correction (FEC) can restore minor reexecution discrepancies and, thus, make operation shipping work with more applications. Operation shipping can be further classified into two types: application-transparent and application-aware. Their feasibilities and benefits have been demonstrated by the design, implementation, and evaluation of a prototype extension to the Coda File System. In our controlled experiments, operation shipping achieved substantial performance improvements---network traffic reductions from 12 times to nearly 400 times and speedups in the range of 1.4 times to nearly 50 times.

While computer processing power, storage space, and bandwidth capacities are experiencing exponential growth, individual human processing capabilities are not increasing significantly. Pervasive computing creates an environment that offers a wealth of computing resources, I/O capabilities, and sensors.

Abstract not found

As Linux clusters have matured as platforms for lowcost, high-performance parallel computing, software packages to provide many key services have emerged, especially in areas such as message passing and networking. One area devoid of support, however, has been parallel file systems, which are critical for highperformance I/O on such clusters. We have developed a parallel file system for Linux clusters, called the Parallel Virtual File System (PVFS). PVFS is intended both as a high-performance parallel file system that anyone can download and use and as a tool for pursuing further research in parallel I/O and parallel file systems for Linux clusters. In this paper, we describe the design and implementation of PVFS and present performance results on the Chiba City cluster at Argonne. We provide performance results for a workload of concurrent reads and writes for various numbers of compute nodes, I/O nodes, and I/O request sizes. We also present performance results for MPI-IO on PVFS, both for a concurrent read/write workload and for the BTIO benchmark. We compare the I/O performance when using a Myrinet network versus a fast-ethernet network for I/O-related communication in PVFS. We obtained read and write bandwidths as high as 700 Mbytes/sec with Myrinet and 225 Mbytes/sec with fast ethernet.

Even though database management as well as workflow management systems have significant advantages, spreadsheets exchanged by e-mail are still in widespread use for many processes within an enterprise, causing problems such as poor data-quality and lack of process monitoring. This paper analyzes reasons for office-document based workflows (ODBWf) and presents an alternative solution that combines the advantages of DBMS and WfMS with the flexibility and simplicity of office documents. This paper introduces an autonomous mobile document-management-system based on a ‘smart’ file. This file is executable and contains a managed resource part where files can be stored. Any read/write access to its resource part is managed by the file itself; it controls who can do what and automatically synchronizes changes to other systems such as process-monitoring or business intelligence tools. Proven concepts from DBMS, such as triggers, integrity constraints and multi-user support are utilized to improve ODBWfs without restraining their flexibility.