Placement of file replicas in data grid environments

In this paper, we address the problem of file replica placement in Data Grids given a certain traffic pattern. We propose a new file replica placement algorithm and compare its performance with a standard replica placement algorithm using simulation. The results show that file replication improve the performance of the data access but the gains depend on several factors including where the file replicas are located, burstness of the request arrival, packet loses and file sizes.

File replacement algorithm for storage resource managers in data grids

The main problem in data grids is how to provide good and timely access to huge data given the limited number and size of storage devices and high latency of the interconnection network. One approach to address this problem is to cache the files locally such that remote access overheads are avoided. Caching requires a cache-replacement algorithm, which is the focus of this paper. Specifically, we propose a new replacement policy and compare it with an existing policy using simulations. The results of the simulation show that the proposed policy performs better than the baseline policy.

Investigation of an optimistic based concurrency control mechanism for parallel file systems

Parallel file systems offer improved performance over traditional file systems by allowing processes to access file data, stored over a number of disks, in parallel. When this file is to be accessed by many processes at the same time for reading and writing, the problem of maintaining file consistency is introduced. The general approach to maintaining file consistency is through the use locks which grant a single process exclusive access to the file. Existing studies have found parallel file systems and associated applications rarely experience conflict, resulting in unnecessary overheads from locks being acquired. This paper examines an alternate approach to maintaining file consistency, which is based on optimistic concurrency control. This approach was shown to have a much smaller overhead when compared with traditional lock-based approaches; especially in situations when there is little contention. This paper presents the design, implementation and initial testing results of an optimistic based concurrency control mechanism.

An effective and efficient testing methodology for correctness testing for file recovery tools

We hereby develop an effective and efficient testing methodology for correctness testing for file recovery tools across different file systems. We assume that the tool tester is familiar with the formats of common file types and has the ability to use the tools correctly. Our methodology first derives a testing plan to minimize the number of runs required to identify the differences in tools with respect to correctness. We also present a case study on correctness testing for file carving tools, which allows us to confirm that the number of necessary testing runs is bounded and our results are statistically sound.

Sharable file searching in unstructured peer-to-peer systems

The existing sharable file searching methods have at least one of the following disadvantages: (1) they are applicable only to certain topology patterns, (2) suffer single point failure, or (3) incur prohibitive maintenance cost. These drawbacks prevent their effective application in unstructured Peer-to-peer (P2P) systems (where the system topologies are changed time to time due to peers' frequently entering and leaving the systems), despite the considerable success of sharing file search in conventional peer-to-peer systems. Motivated by this, we develop several fully dynamic algorithms for searching sharing files in unstructured peer to peer systems. Our solutions can handle any topology pattern with small search time and computational overhead. We also present an in-depth analysis that provides valuable insight into the characteristics of alternative effective search strategies and leads to precision guarantees. Extensive experiments validate our theoretical findings and demonstrate the efficiency of our techniques in practice.

OST : A transaction based online social trust model for social network and file sharing security

The continuous growth of the users pool of Social Networking web sites such as Facebook and MySpace, and their incessant augmentation of services and capabilities will in the future, meet and compare in contrast with today's Content distribution Networks (CDN) and Peer-to-Peer File sharing applications such as Kazaa and BitTorrent, but how can these two main streams applications, that already encounter their own security problems cope with the combined issues, trust for Social Networks, content and index poisoning in CDN? We will address the problems of Social Trust and File Sharing with an overlay level of trust model based on social activity and transactions, this can be an answer to enable users to increase the reliability of their online social life and also enhance the content distribution and create a better file sharing example. The aim of this research is to lower the risk of malicious activity on a given Social Network by applying a correlated trust model, to guarantee the validity of someone's identity, privacy and trustfulness in sharing content.

An efficient and distributed file search in unstructured peer-to-peer networks

Peer-to-peer (P2P) networks are gaining increased attention from both the scientific community and the larger Internet user community. Data retrieval algorithms lie at the center of P2P networks, and this paper addresses the problem of efficiently searching for files in unstructured P2P systems. We propose an Improved Adaptive Probabilistic Search (IAPS) algorithm that is fully distributed and bandwidth efficient. IAPS uses ant-colony optimization and takes file types into consideration in order to search for file container nodes with a high probability of success. We have performed extensive simulations to study the performance of IAPS, and we compare it with the Random Walk and Adaptive Probabilistic Search algorithms. Our experimental results show that IAPS achieves high success rates, high response rates, and significant message reduction.