共查询到19条相似文献,搜索用时 93 毫秒
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混合云环境下,公有云与私有云共同为用户提供服务,公有云中的应用可能需要频繁读取私有云中的数据,通过复制私有云中的副本到公有云中可降低网络开销,但不同云中文件副本的动态更新会导致云中各个副本的不一致性。提出了一致性服务,该服务由一致性维护模块和一致性检测与恢复模块两个部分组成。一致性维护模块通过发送文件的更新消息的方法维护副本的一致,降低了系统的响应时间;一致性检测与恢复模块利用世系的思想,通过对比副本的世系记录来检测副本的一致性,可将副本不一致状态恢复成一致状态。实验证明混合云下利用世系一致性服务是可行的,由此带来的通信和存储开销在可接受范围内。 相似文献
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分布式环境中副本的大量存在满足了系统安全性、可靠性、通信代价以及查询效率方面的要求,同时,副本的访问策略以及一致性维护一直也是困扰分布式数据库理论和实践的重要问题。文章在分析副本更新同步策略的基础上,提出了一种基于分布式环境的副本自动审视技术。详细阐述了该技术指导下的全局字典扩充方法,提出了基于松散一致性维护的同步更新算法和执行策略。该技术在很大程度上提升了现有DDBMS的功能,从而对分布式数据库技术的应用和推广产生了积极的作用。 相似文献
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数据网格中的数据复制技术研究 总被引:4,自引:0,他引:4
数据复制技术是数据网格系统中广泛采用的改善网格系统性能的关键技术之一。与传统分布式系统应用领域中的复制相比,数据网格中的复制技术在复制目标、复制粒度、复制关键技术等方面表现出独特性质。本文将数据复制技术概括为副本创建、数据传输、副本删除、副本选择、副本一致性管理、安全管理等环节,深入分析、探讨了数据网格系统中数据复制的各项关键技术,为建立综合的数据网格复制策略和技术框架提供了全面的技术分析。最后,对数据复制技术下一步的研究方向作了分析和预测。 相似文献
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分布式系统中异地数据库的数据一致性维护 总被引:8,自引:0,他引:8
大型分布式系统通常需要在异地的数据库中存储同一数据的不同副本,不同副本之间需要维护数据的一致性。文章讨论了维护数据一致性的两种方法:消息队列法和复制控制法,并分别介绍了使用IBMMQSeries消息队列和MicrosoftSQLServer复制机制来维护数据一致的实现过程,对比分析了二者在实际应用中各自的特点,以及在理论上的技术差异。 相似文献
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PATCOM:基于分割树的无结构P2P系统一致性维护方法 总被引:2,自引:0,他引:2
无结构P2P技术逐渐被应用在新型的协同计算系统中.这些新型业务支持数据的动态更新,不仅要求副本数据的强一致性,而且要求更新数据的快速传播.高效的一致性维护方法是保证新业务顺利开展的基础.在比较分析现有的P2P系统一致性维护方法的基础上,针对无结构P2P系统,提出了一种基于分割树的一致性维护方法--PATCOM.PATCOM使用Chord协议作为组管理协议,通过不断分割由副本节点组成的Chord环,动态地建立更新消息传播树(Update Message Propagation Tree,UMPT).论文进一步从理论上分析了UMPT的平均高度、PATCOM的性能、容错能力以及算法开销,并和基于Gossip的一致性维护方法进行了比较.理论分析和仿真实验结果表明:PATCOM不仅能够快速地维护P2P系统的强一致性,而且产生的冗余更新消息少. 相似文献
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数据网格中,数据副本技术提高了数据的访问速度,减少了带宽的消耗.副本创建策略是数据副本研究中的重要问题之一.提出了在P2P网络环境下,一种基于滑动窗口技术的副本创建和替换策略.使用传输时间比作为副本创建和替换的依据.分析和模拟显示,该方法能在控制访问空间的同时,获得良好的性能. 相似文献
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副本管理成为影响数据网格性能的主要因素之一,研究高效的副本管理算法大都依赖于对数据网格副本管理进行仿真.介绍了一种数据网格副本管理仿真软件的设计与实现,并详细介绍了数据网格仿真的一些关键技术的解决方案,如任务调度、任务执行仿真. 相似文献
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Data replication techniques are used in data grid to reduce makespan, storage consumption, access latency and network bandwidth. Data replication enhances data availability and thereby increases the system reliability. There are two steps involved in data replication, namely, replica placement and replica selection. Replica placement involves identifying the best possible node to duplicate data based on network latency and user request. Replica selection involves selecting the best replica location to access the data for job execution in the data grid. Various replica placement and selection algorithms are available in the literature. These algorithms measure and analyze different parameters such as bandwidth consumption, access cost, scalability, execution time, storage consumption and makespan. In this paper, various replica placement and selection strategies along with their merits and demerits are discussed. This paper also analyses the performance of various strategies with respect to the parameters mentioned above. In particular, this paper focuses on the dynamic replica placement and selection strategies in the data grid environment. 相似文献
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在因特网的数据网格环境中,将整个网格系统划分为若干个存储子域,基于Globus平台,结合Giggle框架提出三层副本定位服务结构,并提出了基于Giggle的副本定位算法(RLBOG)。分析表明,新算法有效地减少了响应时间,提高了系统性能。 相似文献
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P. Victer PaulAuthor Vitae N. SaravananAuthor Vitae 《Future Generation Computer Systems》2012,28(3):573-582
Replica Management is a key issue to reduce the bandwidth consumption, to improve data availability and to maintain data consistency in large distributed systems. Global Replica Management (GRM) means to maintain the data consistency across the entire network. It is preferable particularly for multi-group distributed systems. On the other hand, GRM is not favorable for many applications because a very large number of message passes is needed for replica management processes. In this paper, in order to reduce the number of message passes needed to achieve the efficient GRM strategy, an interconnection structure called the Distributed Spanning Tree (DST) has been employed. The application of DST converts the peer network into logical layered structures and thereby provides a hierarchical mechanism for replication management. It is proved that this hierarchical approach improves the data availability and consistency across the entire network. In addition to these, it is also proved that the proposed approach reduces the data latency and the required number of message passes for any specific application in the network. 相似文献
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如何高效准确地定位到所需数据的一个或所有副本是当前副本技术的热点问题。提出一种动态可靠的副本定位技术DRRL(Dynamic Reliable Replica Location Method),以完成对所需数据所有副本的定位,DRRL引入域间超节点的定义来支持同一数据所有副本在整个数据网格中的定位,并支持域间超节点的动态加入或者退出。通过定理证明以及实验表明,DRRL具有良好的可靠性及可行性。 相似文献
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Peer-to-peer systems offer attractive system management properties, including the ability of components that join the network
to self-organize; scalability up to tens of thousands of members; the ability of the network to automatically repair its topology
after node failures; and techniques for maintaining redundant information to improve reliability and load balancing. We investigate
applying peer-to-peer techniques to Grid services that are oriented toward resource discovery. In particular, we apply the
Chord structured peer-to-peer overlay network to the Globus Replica Location Service, which allows registration and discovery
of data replicas. We describe the design and performance of a Peer-to-Peer Replica Location Service (P-RLS) that uses the
Chord algorithm to self-organize P-RLS servers and exploits the Chord overlay network to replicate P-RLS mappings adaptively.
We present performance measurements and simulation results for the P-RLS system. We also discuss outstanding issues for applying
peer-to-peer techniques to Grid resource discovery services. 相似文献
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In current large-scale distributed key–value stores, the tail latency of the hundreds of key–value access operations generated by an end-user request determines the response time of this request. Therefore, this tail latency has great impacts on the user experience and revenue. Replica selection algorithms, which select the best replica server for the service of each key–value access operation as much as possible, is the key to cut the tail latency of these key–value access operations. This paper summarizes current replica selection algorithms, including both the algorithms employed by current key–value stores and the classic algorithms of other similar systems. These algorithms are classified into three categories: information-agnostic, client-independence and feedback, according to their demanded information. As a step further, simulation-based performance analysis of these algorithms is conducted. The result brings us the insights that the response time (RPT) is useful to measure the service rate, but will lead to the herd behaviors. Moreover, the number of outstanding key–value access operations (OSKs) is helpful to both the selection of the fastest replica server and the avoidance of herd behaviors. Based on these insights, we design the L2 algorithm by assembling the basic ideas of the Least OSK algorithm and the Least RPT algorithm. The L2 algorithm is much simpler than the recently proposed C3 algorithm and has a similar best performance with C3 as confirmed by the simulation and experimental results. 相似文献