Distributed Hash Table

Over the last decade, storage systems have experienced a 10fold increase between their capacity and bandwidth. This gap is predicted to grow faster with exponentially growing concurrency levels, with future exascales delivering millions of nodes and billions of threads of execution. A critical component of future file systems for high-end computing is metadata management. This extended abstract presents ZHT, a zero-hop distributed hash-table, which has been tuned for the specific requirements of high-end computing. The primary goal of ZHT is excellent availability, fault tolerance, high throughput, and low latencies. 1.

Elastic distributed storage systems have been increasingly studied in recent years because power consumption has become a major problem in data centers. Much progress has been made in improving the agility of resizing small-and large-scale distributed storage systems. However, most of these studies focus on metadata based distributed storage systems. On the other hand, emerging consistent hashing based distributed storage systems are considered to allow better scalability and are highly attractive. We identify challenges in achieving elasticity in consistent hashing based distributed storage. These challenges cannot be easily solved by techniques used in current studies. In this paper, we propose an elastic consistent hashing based distributed storage to solve two problems. First, in order to allow a distributed storage to resize quickly, we modify the data placement algorithm using a primary server design and achieve an equal-work data layout. Second, we propose a selective data reintegration technique to reduce the performance impact when resizing a cluster. Our experimental and trace analysis results confirm that our proposed elastic consistent hashing works effectively and allows significantly better elasticity.

In the growing trend of globalization, the logistics and transportation play the key role in many industries. Products are shipped from one country to another. The heart of this transportation is the port, where large quantities of goods are imported and exported on daily bases. Applying Internet of Things (IoT) technologies to port warehouses is the main area of this work. Centralized warehouse management systems are prone to a single point of failure problem and are not fault tolerant. They have also limited scalability. Another issue is that the port warehouses may run by different companies and the privacy of the detailed product information must be preserved. In this paper, we design an IoT based architecture for warehouse management, according to the facts gathered from the Khorramshahr port. The main issues that this paper tries to address are: scalability, fault tolerance, and privacy. The devised architecture is named Khorramshahr (named after the name of the port). The tailored version of Chord architecture is exploited for a Distributed Hash Table (DHT), which inherits the required scalability and fault tolerance. According to the devised architecture, each company can solely manage its dedicated nodes and preserve the privacy. To boost the lookup process the design is enhanced by Bloom filter and Quotient filter. Moreover, to gain performance the architecture uses a hybrid approach, which combines both the client server and the peer to peer paradigms. To evaluate the performance, the DHT of the architecture is simulated by OMNet++ and OverSim. The simulation results show that by the scaling the number of terminals from 25 to 250 the access time for an item increases only 38%. Besides, the increase in the number of requests from 10,000 to 50,000 depicts 5% and 10% improvement respectively for the lookup message latency compared to the ODSA. The simulation results also exhibit lower false positive rate for the Quotient filter approach, which makes it the first implementation candidate. Only in cases with strict constraints on memory consumption the Bloom filter approach is favored.

One of the crucial building blocks for Information Centric Networking (ICN) is a name based routing scheme that can route directly on content names instead of IP addresses. However, moving the address space from IP addresses to content names brings scalability issues to a whole new level, due to two reasons. First, name aggregation is not as trivial a task as the IP address aggregation in BGP routing. Second, the number of addressable contents in the Internet is several orders of magnitude higher than the number of IP addresses. With the current size of the Internet, name based, anycast routing is very challenging specially when routing efficiency is of prime importance. We propose a novel name-based routing scheme (Route) for ICN that offers efficient bandwidth usage, guaranteed content lookup and scalable routing table size. Route consists of two components: an alphanumeric Distributed Hash Table (DHT) and an overlay to underlay (Internet topology) mapping algorithm. Simulation results show that Route performs significantly better than Content Centric Network (CCN) (by V. Jacobson et al., 2009) in terms of network bandwidth usage, lookup latency and load balancing.

We are experiencing a revolution in the wireless technology and mobile phone networks as they are becoming increasingly ubiquitous. On the other hand, there is another trend, gaining extreme popularity over the traditional wired Internet: Peer-to-Peer (P2P) networking. Specifically, Distributed Hash Table (DHT) based Structured P2P overlay networks are capable to facilitate information storage and retrieval among a potentially very large number of users without the use of central server components. Providing such P2P services in mobile networks will allow a user to harness the potential of P2P services while on the move. However, due to technical issues in mobile phone networks and limited resources available on the handsets, designing such a system is a challenging issue. While the research of P2P overlays in wired networks is plenty, there is a limited study on the suitability of different existing P2P overlays for mobile networks. This article investigates the performance and efficiency of a number of structured P2P overlays that use recursive approach for routing strategy: R/Kademlia, Pastry and Bamboo and finds their suitability for use on mobile networks. The simulation result shows that among the three overlays, Bamboo exhibits a marginally better performance in comparison to the others with a 98% to 99% routing efficiency and a lower bandwidth consumption in high churn environment. Hence, Bamboo protocol is a good choice to be used over Kademlia and Pastry in mobile networks.

The evolution of peer-to-peer (P2P) systems triggered the building of large scale distributed applications. The main application domain is data sharing across a very large number of highly autonomous participants. Building such data sharing systems is particularly challenging because of the “extreme” characteristics of P2P infrastructures: massive distribution, high churn rate, no global control, potentially untrusted participants... This article focuses on declarative querying support, query optimization and data privacy on a major class of P2P systems, that based on Distributed Hash Table (P2P DHT). The usual approaches and the algorithms used by classic distributed systems and databases for providing data privacy and querying services are not well suited to P2P DHT systems. A considerable amount of work was required to adapt them for the new challenges such systems present. This paper describes the most important solutions found. It also identifies important future research trends in data management in P2P DHT systems.

Nowadays, the structure of cloud uses the data processing of simple key value, which cannot adapted in search of closeness effectively because of the lack of structures of effective indexes, and with the increase of dimension, the structures of indexes similar to the tree existing could lead to the problem " of the curse of dimension ". In this paper, we define a new cloud computing architecture in such global index, storage nodes is based on a Distributed Hash Table (DHT). In order to reduce the cost of calculation, store different services on the hyperbolic tree by using virtual coordinates thus that greedy routing based on hyperbolic space properties in order to improve query storage and retrieving performance effectively. Next, we perform and evaluate our cloud computing indexing structure based on a hyperbolic tree using virtual coordinates taken in the hyperbolic plane. We show through our experimental results that we compare with others clouds systems to show our solution ensures consistence and scalability for Cloud platform.

Information sharing among vehicles is one of the emergent issues in Vehicular Ad Hoc Networks (VANETs). Considering the mobility and limited connectivity of the nodes, designing a secure scalable architecture for information sharing is a challenging problem. In this paper, we propose a distributed peer-to-peer (P2P) based architecture for information sharing in Vehicular Ad Hoc Networks. We split the entire network into zones and use a consistent hashing technique to map the nodes and the information to unique identifiers in Distributed Hash Table (DHT). DHT is used to determine the node containing the information requested by a particular user. Ongoing work aims to develop a scalable routing scheme for information sharing VANETs.

We introduce a hybrid High Performance Computing (HPC) infrastructure architecture that provides predictable execution of scientific applications, and scales from a single resource to multiple resources, with different ownership, policy, and geographic locations. We identify three paradigms in the evolution of HPC and high-throughput computing: owner-centric HPC (traditional), Grid computing, and Cloud computing. After analyzing the synergies among HPC, Grid

We developed a new content routing based on the virtual backbone structure, which groups wireless nodes and contents into a virtual architecture. Our approach is scalable, works with local information, and does not rely on address information. The naming system uses flat naming to identify nodes and contents, and organizes these identifiers together. Backbone nodes can be selected automatically or pre-defined to direct their associated normal nodes in a local area. The normal nodes are guided by the backbone nodes to full fill the searching and routing processes. With a virtual structure, the searching performance can be improved by using the DHT technique. Experiments using ns2 simulator demonstrate that this virtual backbone routing architecture has the following significances: workable without being aware address in a mobile situation; scalable with the size of network; efficient in terms of the reduced hop counts and short end-to-end delay, and also resistant to the dead-end problem.