CSR: Small: Collaborative Research: Improving Latency in Geo-Replicated Storage by Relaxing Consistency Requirements

近年来，云服务的普及程度有了巨大的增长。分布式存储系统是云计算革命的关键组成部分。分布式存储系统旨在实现延迟、数据一致性和可靠性之间的适当权衡。该项目致力于开发考虑了应用程序特征和混合故障模型的新一致性模型。最终目标是提高我们对分布式存储系统中一致性、延迟和可靠性之间权衡的理解。该项目包括两个协同重点。首先，该项目探索了考虑基于图的应用程序特征的一致性模型。例如，社交和信任图为许多应用程序建模用户关系和交互。第一个要点探讨了应用程序可以接受的基于图的一致性模型，并且改进了客户端操作的延迟。其次，以前的存储系统通常只能容忍良性故障，或者容忍高开销的最坏情况故障。该项目考虑了非串通故障和拜占庭故障，并研究了通过放松先前系统强加的一些要求来减少开销的方法。所提出的研究有望提高对分布式存储系统中应用特性和不同类型故障对一致性-延迟权衡的影响的理解。对于未来关键的基于web的服务和应用程序，更严重错误的容忍度可能变得非常重要。此外，随着社会和信任网络的巨大增长，提高其性能的机制也引起了人们的兴趣。该项目通过开发新的一致性模型来帮助实现这些改进。此外，该项目还为本科生和研究生以及博士后研究员提供研究机会。项目数据在项目完成后至少保留两年，存储在本地计算机和在线共享存储中。该项目产生的数据、出版物和软件的存储库的URL是https://sites.google.com/site/nsfgeoconsistency/.This，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，认为值得支持。

Recent years have seen a tremendous growth in the popularity of cloud services. Distributed storage systems are a key component of the cloud computing revolution. Distributed storage systems are designed to achieve a suitable tradeoff between latency, data consistency and dependability. This project addresses development of new consistency models that take into account application characteristics and hybrid fault models. The ultimate goal is to improve our understanding of the trade-offs between consistency, latency, and dependability in distributed storage systems. The project includes two synergistic thrusts. First, the project explores consistency models that consider graph-based application characteristics. For example, social and trust graphs model user relation and interaction for many applications. The first thrust explores graph-based consistency models that are acceptable for the applications, and yet improve latency of client operations. Second, prior storage systems typically either only tolerate benign failures, or tolerate worst-case faults with high overhead. This project considers non-colluding faults as well as Byzantine faults, and investigates approaches to reduce overhead by relaxing some of the requirements imposed by prior systems. Proposed research is expected to improve the understanding of the impact of application characteristics and different types of faults on consistency-latency trade-off in distributed storage systems. Tolerance of more severe faults is likely to become important for future critical web-based services and applications. Additionally, with the tremendous growth in social and trust networks, mechanisms to improve their performance are of interest. This project helps achieve such improvements through the development of new consistency models. Additionally, the project provides research opportunities to undergraduate and graduate students, and a post-doctoral researcher.The data from the project is to be retained for at least two years after the completion of this project, and stored in local computers and online shared storage. The URL for the repository of the data, publications and software resulting from the project is https://sites.google.com/site/nsfgeoconsistency/.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.