Replica Consistency Maintenance Research Articles

Scalable and dynamic replica consistency maintenance for edge-cloud system

With the increasing number of edge devices in the Internet of things (IoT), data storage in edge cloud environment better meet the real-time requirements of IoT. In order to improve the data reliability, reduce the overhead and the response latency, and make more reasonable use of storage resources in edge cloud environment, we conduct an in-depth study on the replica creation strategy and consistency maintenance strategy. In order to reduce the waste of storage resources, a dynamic replica creation strategy based on block popularity and node load (DRC-BN) is proposed. DRC-BN strategy considers the storage cost of edge cloud and the communication cost between central cloud and edge cloud when optimizing the number of replicas, and improves the data reliability. In order to solve the problem of data inconsistency caused by multi-user concurrency, a replica consistency maintenance strategy based on Fast Paxos algorithm (RC-FP) is proposed. RC-FP strategy considers the comprehensive performance of nodes and selects the node with better performance as the leader according to the comprehensive performance of nodes, and reduces the time of consistency maintenance. Experimental results show that the proposed strategies perform well in terms of the consistency maintenance time and the node throughput. At the same time, the proposed strategies also reduce the overall overhead.

An Optimized Replica Distribution Method in Cloud Storage System

Aiming at establishing a shared storage environment, cloud storage systems are typical applications of cloud computing. Therefore, data replication technology has become a key research issue in storage systems. Considering the performance of data access and balancing the relationship between replica consistency maintenance costs and the performance of multiple replicas access, the methods of replica catalog design and the information acquisition method are proposed. Moreover, the deputy catalog acquisition method to design and copy the information is given. Then, the nodes with the global replica of the information replicate data resources, which have the high access frequency and the long response time. Afterwards, the Markov chain model is constructed. And a matrix geometric solution is used to export the steady-state solution of the model. The performance parameters in terms of the average response time, finish time, and the replica frequency are given to optimize the number of replicas in the storage system. Finally, numerical results with analysis are proposed to demonstrate the influence of the above parameters on the system performance.

An ant colony model based replica consistency maintenance strategy in unstructured P2P networks

To improve file availability and peers’ retrieval efficiency, many P2P networks adopt file replication techniques to distribute files and their replicas. Thus how to maintain the replica consistency has been an important research focus, especially in the P2P networks with writable and dynamically changeable files. Existing researches suffer from the shortcomings of either needing more update messages or having lower update success rates. This paper proposes a novel replica consistency maintenance strategy based on an ant colony model. We first define an ant’s actions and states, and then we use ants to update replicas in their walking forward and update file’s pheromones in their returning process. We discuss how to tackle the churn problem when an ant returns. The simulation results show that our strategy could reduce the update cost and the impacts caused by churn in replica consistency maintenance in unstructured P2P networks.

EARM: An Efficient and Adaptive File Replication with Consistency Maintenance in P2P Systems

In p2p systems, file replication and replica consistency maintenance are most widely used techniques for better system performance. Most of the file replication methods replicates file in all nodes or at two ends in a clientserver query path or close to the server, leading to low replica utilization, produces unnecessary replicas and hence extra consistency maintenance overhead. Most of the consistency maintenance methods depends on either message spreading or structure based for update message propagation without considering file replication dynamism, leading to inefficient file update and outdated file response. These paper presents an Efficient and Adaptive file Replication and consistency Maintenance (EARM) that combines file replication and consistency maintenance mechanism that achieves higher query efficiency in file replication and consistency maintenance at a low cost. Instead of accepting passively file replicas and updates, each node determines file replication and update polling by adapting to time-varying file query and update rates. Simulation results demonstrate the effectiveness of EARM in comparison with other approaches.

Using optorsim to efficiently simulate replica placement strategies

Optorsim provides simulations of file replication strategies such as replica placement, replication scheduling, replica consistency maintenance, etc. However, to assess a replica strategy a researcher must write network configuration files and repeatedly modify parameters, which is inefficient. In this article, a scale-free algorithm is developed to generate network topology which is loaded into Optorsim, and a graphical user interface (GUI) is implemented to set all configuration parameters and algorithm parameters. Moreover, a new replica placement strategy, the replica creation (RC) algorithm, is proposed based on ‘social ability’. Through the GUI, parameters could be conveniently modified to debug proposed algorithm. The simulation results demonstrate that the RC algorithm can reduce both processing time and storage consumption. Meanwhile, the simulation experience shows that working with Optorsim through the GUI is efficient.