Search

One of the more confusing aspects of using any personal computer is managing the thousands of files that can accumulate over a very short span of years. If you’re like me and keep all of your documents, photos, music, videos, and other random bits of information on your Mac, pretty soon you’ll find it becomes difficult to navigate around all of that data.

Container-based virtualization is the most popular solution for isolating resources among users in a shared testbed. Container achieves good performance but makes the code quite complicated and hard to maintain, to debug and to deploy. We explore an alternative philosophy to enable the isolation based on commodity OS, i.e., utilizing existing features in commodity OS as much as possible rather than introducing complicated containers. Merely granting each user-id in the OS a dedicated and isolated network address as well as specific routing table, we enhance the commodity OS with the functionality of network namespace isolation. We posit that an OS’s built-in features plus our feather-weight enhancement meet basic requirements for separating activities among different users of a shared testbed. Applying our prototype which has been implemented, we demonstrate the functionality of our solution can support a VINI-like environment with marginal cost of engineering and tiny overhead.

The Target infrastructure has been specially built as a storage and compute infrastructure for the information systems derived from Astro-WISE. This infrastructure will be used by several applications that collaborate in the area of information systems within the Target project. It currently consists of 10 PB of storage and thousands of computational cores. The infrastructure has been constructed based on the requirements of the applications. The storage is controlled by the Global Parallel File System of IBM. This file system takes care of the required flexibility by combining storage hardware with different characteristics into a single file system. It is also very scalable, which allows the system to be extended into the future, while replacing old hardware with new technology., Comment: Accepted for publication in topical issue of Experimental Astronomy on Astro-WISE information system

Redundant data transfer over a network is one of the important reasons of traffic congestion today. In this paper, we proposed an efficient and secure file sharing model using de-duplication technology to resolve it. A file sharing based de-duplication system reduce bandwidth and storage at both client and server machine. It does not download duplicate blocks that already have been downloaded. To achieve the security of client data, three-tier architecture is proposed in this work. For this purpose SHA-1 hash function is being used, in which 8KB block of data is converted into a 20 bytes digest. Thus the design presents a dramatic reduction in storage space requirement for various workloads and hence reduces time to perform backup in bandwidth constraint environment.

The understanding of file access patterns is important when developing efficient and effective schemes for file management and allocation in a distributed environment. In addition, a careful analysis of file usage patterns leads to techniques for increasing file availability by means of file duplication without requiring extra disk storage. Based on the static analysis of file usage patterns, this article describes and evaluates an approach to enhance file availability without increasing disk usage. Data were collected from a typical network file system to establish a Markov chain for analyzing the performance of the proposed strategy. We show that a highly available file system is achievable without requiring extra disk storage. Our approach to disk management will be integrated with our new personal file management facility, PFS. PFS creates a global structure of a user's personal files that appears identical without regard to the server that a user accesses.

This paper proposes a DHT-based namespace solution for a Grid system-Virtual Organization File System(VOFS).Different from previous version of VOFS,this solution doesn't demand complete namespace metadata be stored in all peers.By using peer-to-peer Chord, specified peers are chosen for storing specified namespace of resource.

The vision of cross-domain file systems is becoming a reality; however, issues like ensuring quality of service for bandwidth-intense resource access, especially over mobile network, may still arise. In this paper, we propose a cross-domain shared file system, which enables a real-time experience for delivery of virtualized file systems utilizing a grid approach over NGN. The system allows users to share file systems in real-time, and provides functions to delivery update notification, to ensure access control settings, and to offer real-time streaming access to the virtual resources. We describe the system design, and a file sharing scenario to show the details of the prototyped solution. Finally, we give an outlook on the future improvements that could be made to the system.

The instability of the network and storage nodes may lead to the failure of the storage process in the network storage environment. In this paper, we establish the realibility model of the storage node availability, and the probability model of a success file block storage process, give the Store-After-Partition Strategy, compare the probabilities of a success file storage process at different partition granularities, and finally put forward the optimal strategy of file partition among network storage environment. This strategy is valuable for network storage facing massive files.

Rapid technological evolutions in mobile industry have revealed new challenges for scientists and researchers by empowering low-end devices in the last decade. Mobile phones with excellent computing power and added features especially with huge storage capacities are very common in the market. As the storage capacity grows on such a device, it becomes very tedious for users to manage and organize different type of files. The file system of such devices itself provide some managing mechanism to store same type of files separately however it proves scarce as the number of files grows. Furthermore, limited user interface on these devices makes file retrieval more difficult. This paper presents detailed analysis of meta-data significance in our proposed framework to annotate and search files on low-end mobile devices. File attributes are extracted from the underlying operating system of the device and used as metadata of the corresponding file. The meta-data is then used for searching the required file. The file search can be performed on the device itself or on other devices when connected in a Personal Area Network (PAN) through Bluetooth. The proposed framework is implemented in Java Micro Edition and a full featured application is developed to demonstrate its validity. The application provides annotation, search options, Bluetooth module, file sharing and transfer options. Results from various performance tests show significant improvement in searching a required file through our proposed framework.

A Previously traditional methods were sufficient to protect the information, since it is simplicity in the past does not need complicated methods but with the progress of information technology, it become easy to attack systems, and detection of hiding methods became necessary to find ways parallel with the differing methods used by hackers, so the embedding methods could be under surveillance from system managers in an organization that requires the high level of security. This fact requires researches on new hiding methods and cover objects which hidden information is embedded in. It is the result from the researches to embed information in executable files, but when will use the executable file for cover they have many challenges must be taken into consideration which is any changes made to the file will be firstly detected by untie viruses; secondly the functionality of the file is not still functioning. In this paper, a new information hiding system is presented. The aim of the proposed system is to hide information (data file) after end of header file within execution file (EXEfile) to make sure changes made to the file will not be detected by universe and the functionality of the exe.file is still functioning after hiding process. Meanwhile, since the cover file might be used to identify hiding information, the proposed system considers overcoming this dilemma by using the execution file as a cover file.

This paper addresses the Information Retrieval issues by today's hierarchical systems such as file systems. They usually contain substantial amount of redundant items. Maintaining the structure becomes difficult when large amount of items exist and ambiguity occurs in the structure. In this study, a conceptual method is presented that replaces the “containment” principle involved in current systems by “membership” principle. The proposed Conceptual File Management (CFM) method allows a file to be accessed from multiple folders; furthermore, it keeps the current hierarchical structure with minor changes. CFM reduces the ambiguity and redundancy, therefore the quality of information retrieval is improved. A Conceptual File Manager based on the above-mentioned principle has been developed. Experiments show that it improves the quality of the system in terms of maintaining the structure and retrieving the desired items easier and faster based on users' viewpoints. CFM is applicable to not only traditional file systems on computers, but also file systems on cell phones (and message storage systems), site maps in Web sites, Content Management Systems, taxonomies, and in general, classification based structures.

With data amount growing at an ever increasing rate, file system, as the basis of data management, its functionality and content are becoming more and more complex. Thus the file system is forced to be upgraded constantly, in order to satisfy the growing demands. However, the reinvention of new file systems is always a high-cost task. Although there are frameworks such as User-space File System that may help speeding up the development process, ease the pain of deploying new functions, they also bring in significant overhead, especially when file operation frequency is fairly high. We designed and implemented a lightweight file system management framework based on LD_PRELOAD in user-space referred to as User-Space Preload (USP), and tested several management tasks with it. According to the comparison with FUSE, USP-based file system management achieved an obvious performance improvement.

Distributed file systems have become popular in recent years. However, they still lack functions for doing fast arbitrary data insertion and truncation. To solve the problem, we present Wofs, an object-based distributed network file system which supports fast arbitrary data insertion and truncation. Wofs splits a file into many small objects, stores these objects in remote file servers, and uses a special B+tree [1][4] to manage the metadata of these objects. Besides, Wofs uses the object-range locking policy to avoid data incoherence and improve performance.

Peer-to-Peer (P2P) file sharing is one of key technologies for achieving attractive P2P multimedia social networking. In P2P file-sharing systems, file availability is improved by cooperative users who cache and share files. Note that file caching carries costs such as storage consumption and processing load. In addition, users have different degrees of cooperativity in file caching and they are in different surrounding environments arising from the topological structure of P2P networks. With evolutionary game theory, this paper evaluates the performance of P2P file sharing systems in such heterogeneous environments. Using micro-macro dynamics, we analyze the impact of the heterogeneity of user selfishness on the file availability and system stability. Further, through simulation experiments with agent-based dynamics, we reveal how other aspects, for example, synchronization among nodes and topological structure, affect the system performance. Both analytical and simulation results show that the environmental heterogeneity contributes to the file availability and system stability.

A Grid computing environment allows forming Virtual Organizations (VOs) to aggregate and share resources. We present a VO File System (VOFS) which is a VO-aware distributed file system that allows VO members to share files. VOFS supports access and location transparency by maintaining a common file namespace, which is decentralized in order to improve robustness. VOFS includes a P2P system of file servers, a VO membership service and a policy and role based security mechanism. VOFS can be mounted to a local file system in order to access files using POSIX file API. VOFS can operate in a dynamic Grid environment (e.g. desktop Grids) since it tolerates unplanned resource arrival and departure (churn) while maintaining a single uniform namespace. It supports transparent disconnected operations that allow the user to work on files while being disconnected.

With the emergence of Ethernet services based on carrier grade Ethernet as transport technology in metro and backbone networks a new addressing schema is required to achieve a global namespace. As native Ethernet does not provide unique identifiers, which are needed for inter-provider services, we propose a novel naming schema which allows for human readable endpoint identifiers, at the same time avoiding the disclosure of provider internal structures. These addresses are used to establish a connection path suiting the customers' needs. Additionally we propose security mechanisms to authenticate and authorize peers of Ethernet services.

A Google map resides in a web page. So, the first thing you need to do is to set up that page. This includes creating an HTML page and a style sheet for it. Once you have everything set up, you can insert the actual map. In this chapter, I will guide you through all the necessary steps to create your very first Google Maps page.

The increasing need for data sharing in large-scale distributed systems may place a heavy burden on critical resources such as file servers and networks. Our examination of the workload in one large commercial engineering environment shows that wide-spread sharing of unstable files among tens to hundreds of users is common. Traditional client-based file cacheing techniques are not scalable in such environments. We propose Frolic, a scheme for cluster-based file replication in large-scale distributed file systems. A cluster is a group of workstations and one or more file servers on a local area network. Large distributed systems may have tens or hundreds of clusters connected by a backbone network. By dynamically creating and maintaining replicas of shared files on the file servers in the clusters using those files, we effectively reduce reliance on central servers supporting such files, as well as reduce the distances between the accessing sites and data. We propose and study algorithms for the two main issues in Frolic, 1) locating a valid file replica, and 2) maintaining consistency among replicas. Our simulation experiments using a statistical workload model based upon measurement data and real workload characteristics show that cluster-based file replication can significantly reduce file access delays and server and backbone network utilizations in large-scale distributed systems over a wide range of workload conditions. The workload characteristics most critical to replication performance are: the size of shared files, the number of clusters that modify a file, and the number of consecutive accesses to files from a particular cluster.

The performance analysis of a system in which storage is provided by a file server node on a network of client processors is discussed. The server controls a hierarchy of storage devices, and provides all the necessary file management functions. The clients are large mainframe systems that have their own local storage devices. The movement of files among the various storage levels is managed by a hierarchical storage management system. A closed queuing network model of the client-server storage system is used to analyze the performance of the system for various file movement criteria and to study the tradeoffs between recalling a file and accessing it by a distributed file system. Several network topologies (Ethernet, token ring, channel-to-channel) and their effect on performance are considered. >

With the improvement of computer networks and the growth of bandwidth, the types of Internet traffic have changed. The P2P file sharing application became the significant source of network traffic. This paper examines the features for P2P file sharing application according to the packets of OSI layer 3 and layer 4. Four features are defined in this paper, including quantity of packet count, percentage of TCP packet count, percentage of specific size of packet count, and percentage of duplicate destination port numbers. Based on these features, the hosts running P2P file sharing application can be identified. The specific signatures in the payload of OSI layer 7 are used to verify which P2P file sharing application the host is running.

The rapid development of network technologies has seen the use of network as a media for file storage and sharing. Files stored on network are expected to be shared in a safe and effective manner. Most recent researches on secure network storage focus solely on security and give little concern to support for information retrieval and in turn information sharing. This paper presents a novel network storage model which integrates techniques in compression, encryption and information retrieval. It effectively satisfies the concern for both security and sharing. Its performance is also demonstrated via experiments on a prototype system.

File replication and file consistency maintenance are two important protocols for achieving overall high performance of peer-to-peer file sharing systems. In spite of the significant dependency of consistency maintenance on file replication, there has been little file replication research devoted to tackling the dependency issue. Most traditional file replication protocols focus on improving file lookup efficiency without considering the subsequent consistency maintenance. This paper presents a COoperative file Replication Protocol (CORP). CORP observes a set of factors including file update rate, file popularity, node available capacity, file load and node locality that affect the efficiency of consistency maintenance. It considers these factors to achieve high efficiency not only in file replication but also in consistency maintenance. CORP generates less replicas and optimally chooses infrequently-updated or popular files to replicate. In addition, it makes file replicas in physically close nodes. Further, CORP can dynamically adjust the number of replicas based on ever-changing file popularity and visit pattern. Simulation results demonstrate the efficiency and effectiveness of CORP in comparison with other file replication protocols. It dramatically reduces the overhead of both file replication and consistency maintenance. Moreover, it yields significant improvement in reducing overloaded nodes.

The object-based storage system stripes data across large numbers of object-based storage devices (OSDs) to enable parallel data access. Subsequently, the workload presented to the individual OSD will be quite different from that of general purpose file systems. However, many distributed file systems employ general-purpose file systems as their underlying file system. This paper presents a Versatile Object-based File System (referred to as V-OBFS), an extent and B+tree based file system designed for use in OSDs. The V-OBFS implements flexible disk layout with multiple block size and differentiated free space management for both small objects and large objects. In addition, proposed V-OBFS enables fast object search and mapping between object ID and physical location with an efficient object namespace management. Our experiments show that our user-level implementation of V-OBFS can efficiently prevent file system fragmentation and outperforms Linux Ext2 and Ext3 by a factor of two or three.

In peer-to-peer file sharing systems, file replication helps to avoid overloading file owners and improve file query efficiency. Aiming to achieve high replica utilization and efficient file query with low overhead, this paper presents a file replication mechanism based on swarm intelligence, namely SWARM. Recognizing the power of collective behaviors, SWARM identifies node swarms with common node interests and close proximity. It determines the location of a file replica based on the accumulated query rates of nodes in a swarm. Replicas are shared by the nodes in a swarm, leading to less replicas and high query efficiency. Simulation results demonstrate the efficiency and effectiveness of the SWARM mechanism in comparison with other file replication methods.

Peer-to-peer file sharing applications are increas- ingly popular and they enable users to share various files with high scalability. However, in intermittently connected mobile network environment, existing file sharing systems are hindered by the lack of node stable connectivity and constant network topology change. We propose a social network based file sharing system in mobile P2P networks. It takes advantage of node mobility and builds communities based on social network. Instead of being hindered by the mobility of the nodes, the proposed system utilizes the node mobility to facilitate communications and provide efficient message routing and file retrieval services. Experiment results show that the proposed system significantly lowers the transmission cost and achieves satisfactory file re- trieval success rate. I. INTRODUCTION In the past few years, the improvement of microelectronics results in dramatic increase of the availability of personal mo- bile devices, such as laptops, powerful PDAs and smart mobile phones. With the convenient devices, the mobile devices can share user-generated contents and interested resources through computer networks. They can interact with the users and share files via Internet. In the case that Internet infrastructures are unavailable, the mobile devices share files through mobile connections, which can be regarded as a mobile peer-to-peer (P2P) network. In mobile P2P networks, peers are intermit- tently connected, which makes traditional approaches of file searching and file sharing between two distant peers almost infeasible. It is a challenging problem to build file-sharing systems in mobile P2P network environment with frequent disconnections of nodes and dynamic topology. In this paper, we design a social network based file sharing system in mobile P2P networks. It leads to low network overhead and offers satisfactory transmission success rate. Our contribution in this paper is two-fold. First, we cluster the peers in the mobile P2P network to different communities based on their interests and enable users to retrieve files in their communities, which reduces traffic cost without reduc- ing file searching success rate. Second, we exploit different mobility of the nodes for file searching and inter-community communication. Peers in the mobile P2P networks are assigned different tasks based on their characteristics of stability or mobility, so that peers can better utilize their resources and make more contributions to file searching and file retrieving. The social network based community, routing algorithm and exploitation of stability and mobility bring about significantly

With the development of network infrastructure and grid technology, a large quantity of file resources are required to be accessed and shared especially in scientific area. However the heterogeneous characteristic of these file resources brings a big challenge to programmer. We have designed and implemented the File Resource Broker (FRB), a light-weight and easy-to-use system for integrating heterogeneous files resources. With FRB, users could organize, manage and access heterogeneous file resources under a unified view in which file resources are organized into a directory tree. The underlying transfer mechanism is transparent to users, which makes heterogeneous file resources behave as local files. Experimental results show that FRB provides high performance of accessing file resources. The response time and transport speed of heterogeneous file resources are fast.

Flash memory has become a popular device due to its huge-capacity, low-power consumption, non-volatility, and shock-resistance. A flash-memory storage system has replaced a hard-disk drive in many applications, especially in embedded systems. Recently, the implementation of file systems on flash-memory storage systems has become an important research topic. How to efficiently manage files and handle file accesses becomes an important issue. In this paper, we will propose a low-memory management for log-based file systems on flash memory. The experimental results show that the proposed method can provide reasonable performance under a low-memory environment.

Customers always complain that anti-virus soft- wares bog down their computers by consuming much of PC memories and resources. With the popularity and variety of zero- day threats over the Internet, security companies have to keep on inserting new virus signatures into their databases. However, is the increasing size of the signature file the sole reason to drag computers to a crawl during the virus scan? This paper outlines other three reasons for slowing down software-protected computers, which actually are not directly related to the signature file. First, the rising time consumption of de-obfuscating binary payloads by using the emulation technology requires anti-virus softwares take more time to scan a packed file than an unpacked file. Second, New Technology File System causes self-similarity in file index searching and data block accessing. Even if file sizes fit the log-normal distribution, there are still many "spikes" of high virus-scanning latency which cannot be ignored. Last but not least, temporal changes in file size, file type, and storage capacity in modern operation systems are slowing down virus scan. The paper also discusses the cloud-based security infrastructure for deploying a light-weight and fast anti-virus products.

In cluster file system, data distribution and load balancing become increasingly important. This paper presents a high performance Run-time Active Block Layout (RABL) mechanism which cans dynamically replicate and optimize the frequently accessed data blocks in the heterogeneous cluster file system. The works in this paper include: (1) presents a dynamic replicating and placing mechanism for the frequent accessed block in cluster file system; (2) presents a file temperature monitor mechanism for the heterogeneous cluster file system without obvious loss of performance. The experiments in paper show that the RABL can effectively improve the performance of the cluster file system.

In WiFi-based content distribution community infrastructure (CDCI), file servers are deployed in diverse locations around cities, caching popular files interesting to a community. They serve file download requests from mobile users in proximity via WiFi. In this paper, we study the optimal caching strategy for file servers in CDCI so that the mean file retrieval probability within deadline is maximized, subject to storage capacity constraints of each file server. The optimal caching strategy depends on many factors, such as users' mobility patterns, access point topology, file popularity, etc. We have formalized this content management problem as a mixed integer optimization problem. Because of NPhardness and a large variable space of this optimization problem, we propose a heuristic algorithm MobaSsign to allocate file blocks. Extensive experiments show that our heuristic caching strategy considering mobility patterns improves the file retrieval probability within deadline.

Increasingly advances in file carving, memory analysis and network forensics requires the ability to identify the underlying type of a file given only a file fragment. Work to date on this problem has relied on identification of specific byte sequences in file headers and footers, and the use of statistical analysis and machine learning algorithms taken from the middle of the file. We argue that these approaches are fundamentally flawed because they fail to consider the inherent internal structure in widely used file types such as PDF, DOC, and ZIP. We support our argument with a bottom-up examination of some popular formats and an analysis of TK PDF files. Based on our analysis, we argue that specialized methods targeted to each specific file type will be necessary to make progress in this area.

Hierarchical folders have been widely used for managing digital files. Previous research has revealed problems with them. Users frequently have to turn to desktop search to re-find files, even if they thought they had saved them in a memorable place. Tagging may have the potential to improve information navigation and organization. This research in progress aims at exploring the possibility of incorporating tagging into the hierarchical folder structure for file management, especially for the process of file organization and file re-finding. This work will provide design implications for future file management tools.

Programs that interact with the file system are a classical challenge for automated software testing. A common approach to handling this problem is to insert an abstraction layer between the application and the file system. However, even with a well-defined abstraction layer, the burden on the software developer or tester is still high: they have to understand the subtleties of the file system to craft a meaningful set of test cases. The file system is accessed through a complex API, which often causes developers to overlook obscure yet possible corner cases. In this paper, we present a parameterized model of the file system that can be used in conjunction with Pex, an automated test generation tool, to test code that depends on the file system.

Content pollution is pervasive in the current peer-to-peer file sharing systems. Many previous reputation models have been proposed to address this problem, however, such models strongly rely on the participants' feedback.In this paper, we bring forward a new holistic mechanism which integrates the reputation model, inherent file-source-based information and the statistical data reflecting the diffusion state to defend against pollution attack. First, we deploy a redundancy mechanism to assure that the file requester receives the correct indices that accord with the information published by the file provider. Second, we complement the reputation information with the diffusion data to help the file requester select the authentic file for downloading. Finally, we introduce a block-oriented probabilistic verification protocol to help the file requester discern the polluted files during the downloading with a low cost.We perform a simulation which shows that our holistic mechanism can perform very well and converge to a high accuracy rapidly, even in a highly malicious environment.

In today’s networked world, file sharing is an essential function needed by almost all computer users. Modern operating systems support different types of file sharing services such as anonymous FTP downloads, network printing, and remote directories. Since Linux was created with networking in mind from the beginning, we can seamlessly implement frequently used file sharing services when the need arises.

Efficient file query is important to the overall performance of Peer-to-Peer (P2P) file sharing systems. In this paper, we introduce an interest-based P2P file sharing system based on a structured P2P. It groups peers based on both interest and proximity. The proposed system is able to support sophisticated routing and clustering strategies based on the file attribute and topology used. Simulation results demonstrate the efficiency of the proposed system in comparison with another P2P file sharing system. It dramatically reduces the overhead and yields significant improvements in file query efficiency.

Building large-scale distributed systems that are decentralized is challenging. Distributed Hash Tables, or structured overlays, attempted to make the process of building these distributed systems easier, by abstracting away many of the complexities of the physical topology, and provide a virtual namespace. The virtual namespace can then be exploited, for example to build or maintain other data structures like a tree to support application-level multicast or group communication. Because the namespace is independent of the underlying physical topology, it can be used to help mitigate the impact of network topology change, for example through churn. A challenge is to understand how to exploit the difference between a physical topology and a virtual topology (or namespace). In the first half of the talk, using examples from a number of systems I have worked on over the years, I will highlight how a namespace can be used and the differences between algorithms designed to work in virtual versus physical topologies. In the second half of the talk I will then outline how recently we have begun more deeply exploring the relationship between physical and virtual topologies. The first is exploiting a virtual topology to enable disruption-tolerant routing protocols that can work on networks that are frequently and dynamically partitioning. The second is examining how we can build physical topologies that are more aligned to a virtual topology, and how this makes building servers that run in Internet-scale Data Centres easier to implement.

This paper designed and realized a P2P file sharing system (FSP2P) by using Java network programming. An adapter was contained in FSP2P. By using the adapter, FSP2P not only can be array to pure IPv4 or IPv6 network, but also can be array to IPv4/IPv6 coexistent network. So, it realized transparent connect between IPv4 and IPv6 in P2P file sharing system.

Efficient file query is important to the overall performance of Peer-to-Peer (P2P) file sharing systems. Clustering peers by their common interests can significantly enhance the efficiency of file query. On the other hand, clustering peers by their physical proximity can also improve file query performance. Few current works are able to cluster peers based on both peer interest and physical proximity. It is even harder to realize it in structured P2Ps due to their strictly defined topologies, although they provide higher file query efficiency than unstructured P2Ps. In this paper, we introduce a proximity-aware and interest-clustered P2P file sharing system (PAIS) based on a structured P2P. It groups peers based on both interest and proximity. PAIS supports sophisticated routing and clustering strategies based on a hierarchical topology. Theoretical analysis and simulation results demonstrate that PAIS dramatically reduces the overhead and enhances efficiency in file sharing.

We propose a three-level SuperPeer network (TSN) for file sharing built on a SuperPeer network. The TSN adopts a SuperPeer P2P network capable of providing file management and the structured P2P network capable of searching file as its basic structure. It is required to dynamically reconstruct its network topology according to changes in peer state and file hot. We propose an autonomic, distributed, and cooperative method to redistribute files dynamically among peers based on file popularity. In simulation experiments, we first set up a network topology that ensures reliable file search. This is carried out under the assumption that the load state of all peers in the network can be obtained in advance. The results show that the file searching in the TSN system is more efficient than in the SuperPeer system.

Within the workplace setting, people need to provide sufficient access to files to allow collaboration, without inadvertently exposing sensitive files. Evidence suggests that file sharing problems exist, and decrease security and interfere with collaboration. A potential solution for managing these problems is to present the user with clear information about file sharing settings and activities. Current file managers either hide the information or simply do not provide it. Using an awareness framework, we identified the core information that users need to be aware of for file sharing situations, performed two studies to determine how to best represent those concepts as labels and icons, and developed a prototype for a file manager that reveals file sharing activity. The results of these design activities can be adopted for other file sharing applications, improving their security and collaborative usability.

As file system capacities reach the petascale, it is becoming increasingly difficult for users to organize, find, and manage their data. File system search has the potential to greatly improve how users manage and access files. Unfortunately, existing file system search is designed for smaller scale systems, making it difficult for existing solutions to scale to petascale files systems. In this paper, we motivate the importance of file system search in petascale file systems and present a new full text file system search design for petascale file systems. Unlike existing solutions, our design exploits file system properties. Using a novel index partitioning mechanism that utilizes file system namespace locality, we are able to improve search scalability and performance and we discuss how such a design can potentially improve search security and ranking.We describe how our design can be implemented within the Ceph petascale file system.

In this paper, we present a visual representation of access control permissions in a standard hierarchical file system. Our visualization of file permissions leverages treemaps, a popular graphical representation of hierarchical data. In particular, we present a visualization of access control for the NTFS file system that can help a non-expert user understand and manipulate file system permissions in a simple and effective way. While our examples are based on NTFS, our approach can be used for many other hierarchical file systems as well.

In peer-to-peer file sharing systems, file replication technology is widely used to reduce hot spots and improve file query efficiency. Most current file replication methods replicate files in all nodes or two endpoints on a client-server query path. However, these methods either have low effectiveness or come at a cost of high overhead. This paper presents an Efficient and adaptive decentralized file replication algorithm (EAD) that achieves high query efficiency and high replica utilization at a significantly low cost. EAD enhances the utilization of file replicas by selecting query traffic hubs and frequent requesters as replica nodes, and dynamically adapting to non-uniform and time-varying file popularity and node interest. Unlike current methods, EAD creates and deletes replicas in a decentralized self-adaptive manner while guarantees high replica utilization. Simulation results demonstrate the efficiency and effectiveness of EAD in comparison with other approaches in both static and dynamic environments. It dramatically reduces the overhead of file replication, and yields significant improvements on the efficiency and effectiveness of file replication in terms of query efficiency, replica hit rate and overloaded nodes reduction.

The distributed file system (DFS) provides a mechanism where a file can be stored across several physical computer nodes ensuring replication transparency and failure transparency. In order to achieve this, one important feature of DFS's data structure is to employ a proper way to organize the large scale data and file namespaces to provide a fast access speed. In order to analyze file namespace issue, we present the comparison among three major data structures, AVL, Red-Black (RB) and B trees which are popular for organizing file namespace for DFS. This paper also presents significant results obtained from our intensive experiments. From the results collected, we conduct a precise vision about the performance comparison of these data structures and propose that AVL tree is the most appropriate solution.

Applications that process large volumes of data (such as, search engines, grid computing applications, data mining applications, etc.) require a backend infrastructure for storing data. The distributed file system is the central component for storing data infrastructure. There have been many projects focused on network computing that have designed and implemented distributed file systems with a variety of architectures and functionalities. In this paper, we develop a comprehensive taxonomy for describing distributed file system architectures and use this taxonomy to survey existing distributed file system implementations in very large-scale network computing systems such as Grids, Search Engines, etc. We use the taxonomy and the survey results to identify architectural approaches that have not been fully explored in the distributed file system research.

International audience; As more and more large-scale applications need to generate and process very large volumes of data, the need for adequate storage facilities is growing. It becomes crucial to efficiently and reliably store and retrieve large sets of data that may be shared at the global scale. Based on previous systems for global data sharing (global file systems, grid data-sharing services), this paper proposes a hierarchical approach for grid storage, which combines the access efficiency of RAM storage with the scalability and persistence of the global file system approach. Our proposal has been validated through a prototype that couples the Gfarm file system with the JuxMem data-sharing service. Experiments on the Grid'5000 testbed confirm the advantages of our approach.

File correlation, which refers to a relationship among related files that can manifest in the form of their common access locality (temporal and/or spatial), has become an increasingly important consideration for performance enhancement in peta-scale storage systems. Previous studies on file correlations mainly concern with two aspects of files: file access sequence and semantic attribute. Based on mining with regard to these two aspects of file systems, various strategies have been proposed to optimize the overall system performance. Unfortunately, all of these studies consider either file access sequences or semantic attribute information separately and in isolation, thus unable to accurately and effectively mine file correlations, especially in large-scale distributed storage systems.This paper introduces a novel File Access coRrelation Mining and Evaluation Reference model (FARMER) for optimizing petascale file system performance that judiciously considers both file access sequences and semantic attributes simultaneously to evaluate the degree of file correlations by leveraging the Vector Space Model (VSM) technique adopted from the Information Retrieval field. We extract the file correlation knowledge from some typical file system traces using FARMER, and incorporate FARMER into a real large-scale object-based storage system as a case study to dynamically infer file correlations and evaluate the benefits and costs of a FARMER-enabled prefetching algorithm for the metadata servers under real file system workloads. Experimental results show that FARMER can mine and evaluate file correlations more accurately and effectively. More significantly, the FARMER-enabled prefetching algorithm is shown to reduce the metadata operations latency by approximately 24-35% when compared to a state-of-the-art metadata prefetching algorithm and a commonly used replacement policy.

To share and exchange the files among Internet users, peer-to-peer (P2P) applications build another layer of overlay networks on top of the Internet infrastructure. In P2P file sharing systems, a file request takes two steps. First, a routing message is generated by the client (request initiator) and spread to the overlay network. After the process finishes, the location information of the requested file is returned to the client. In the second step, the client establishes direct connection(s) with the peer(s) who store a copy of that file to start the retrieving process. While numerous research projects have been conducted to design efficient, high-performance routing algorithms, few work concentrated on file retrieving performance. In this paper, we propose a novel and efficient algorithm - PROD to improve the file retrieving performance in DHT based overlay networks. In PROD, when a file or a portion of a file is transferred from a source peer to the client, instead of creating just one direct link between these two peers, we build an application level connection chain. Along the chain, multiple network links are established. Each intermediate peer on this chain uses a store-and-forward mechanism for the data transfer. PROD also introduces a novel topological based strategy to choose these peers and guarantees the transmission delay of each intermediate link is much lower than the direct link. We conducted extensive simulation experiments and the results shown that PROD can greatly reduce the transfer time per file in DHT base P2P systems.

With the growth of many open source operating systems comes the introduction of open source file systems that allow free modification. File system modifications can be a method of users to evade investigators who use commercial tools to analyze the suspect's media. Investigators need to be aware of what is possible and ways to circumvent the methods that users can utilize when modifying their file system to hide data.