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Wireless Sensor Nodes often need to store or cache measurement or operational data into some non-volatile memory. Many applications using low power sensor nodes are based on Contiki, which provides the COFFEE file system for data storage. As COFFEE introduces occasional long and hard to predict write delays, it can not be used in applications which have real time demands, such as sensor networks operating in industrial environments. In this paper we present an efficient implementation of a flexible Ring File System for Contiki, that can be used in real-time applications. Read and write times are predictable and adherence to Contiki's file system API allows it to be used as a drop-in replacement for COFFEE in many applications. [ABSTRACT FROM PUBLISHER]

Computing systems trust and reputation representation have been widely discussed and applied in a lot of information technology scenarios, becoming subject of scientific researches both from a theoretical and practical point of view. This paper proposes the development of a trust model to ensure a reliable files exchange among users in a private cloud, as well as the calculation process of trust among these users, according to the metrics previously established. The simulation result shows that this trust model is robust because it successfully access node reliable under Private Cloud Computing environment. [ABSTRACT FROM PUBLISHER]

Reorganization of storage data layout is a famous I/O performance improvement method. Many methods have been studied. These methods improve I/O performance by reducing storage seek distances. In virtualized environment, a storage device has several huge image files. Thus, I/O performance is severely decreased by many long distance seeks among these files. Accordingly, I/O performance is expected to be significantly improved by reorganizing data layout in this environment. However, existing reorganizing methods were published before virtualized environment has emerged and take no account of virtualized environment. Thus, the existing methods cannot improve I/O performance largely in virtualized environment. In this paper, we present performance evaluation of the existing reorganizing methods in virtualized environment. After that, we propose a reorganizing method suitable for virtualized environment. Finally, we demonstrate that the propose method outperforms the existing methods with experiments. [ABSTRACT FROM PUBLISHER]

Although the distributed file system is a widely used technology in local area networks, it has seen less use on the wide area networks that connect clusters, clouds, and grids. One reason for this is access control: existing file system technologies require either the client machine to be fully trusted, or the client process to hold a high value user credential, neither of which is practical in large scale systems. To address this problem, we have designed a system for fine-grained access control which dramatically reduces the amount of trust required of a batch job accessing a distributed file system. We have implemented this system in the context of the Chirp user-level distributed file system used in clusters, clouds, and grids, but the concepts can be applied to almost any other storage system. The system is evaluated to show that performance and scalability are similar to other authentication methods. The paper concludes with a discussion of integrating the authentication system into workflow systems. [ABSTRACT FROM PUBLISHER]