CSR: Small: Practical Geo-Replicated Storage for Web Applications

越来越多的人需要跨多个数据中心部署web应用程序，以提高容错性并减少网络延迟。由于应用服务器需要共享数据，如果存在一个存储后端，应用程序可以无缝地访问不同数据中心的复制数据，那么应用服务器的构建可以大大简化。异地复制存储系统面临着一致性的令人不快的权衡。由于大的数据中心间通信延迟导致的性能。本文研究了一种易于使用且具有良好性能的非复制存储一致性和编程模型。特别是，该项目提出了并行快照隔离，这是一种新颖的一致性模型，可以在数据中心之间以最小的协调实现高效。并行快照隔离通过禁止写-写冲突和保留操作的因果关系，提供了比现有的弱一致性模型更强的保证。piv构建了Walter，这是一个地理复制的事务性键值存储，可保证并行快照隔离。许多常见的web应用程序都是在Walter的基础上编写的，评估表明，新的一致性模型易于编程，并使应用程序能够实现高性能。这个项目的成功将大大提高编写可扩展和容错web应用程序的技术水平。

There is increasing demand to deploy web applications across multiple datacenters to improve fault tolerance and reduce network delays tousers. As application servers need to share data, theirconstruction can be significantly simplified if a storage backend exists forapplications to seamlessly access replicated data at different data centers.A geo-replicated storage system faces the unpleasant tradeoff of consistencyvs. performance because of large inter-data-center communication delay. Thisproposal investigates novel consistency and programming models forgeo-replicated storage that are easy-to-use and can achieve good performance.In particular, this project proposes parallel snapshot isolation, a novel consistency model that enables efficient implementation with minimalcoordination across data centers. Parallel snapshot isolation provides muchstronger guarantees than existing weak consistency models by disallowingwrite-write conflicts and preserving the causality of operations. The PIbuilds Walter, a geo-replicated transactional key-value store that guaranteesparallel snapshot isolation. A number of common web applications are writtenon top of Walter and evaluations demonstrate that the new consistency model iseasy to program for and enables applications to achieve high performance. Thesuccess of this project will bring much improvement to the state-of-art inwriting scalable and fault tolerant web applications.