Elsa:一种面向跨区域架构的无协调分布式键值存储系统

作为具备高性能和高可伸缩性的分布式存储解决方案,键值存储系统近年来被广泛采用,例如Redis、MongoDB、Cassandra等.分布式存储系统中广泛使用的多副本机制一方面提高了系统吞吐量和可靠性,但同时也增加了系统协调和副本一致性的额外开销.对于跨域分布式系统来说,远距离的副本协调开销甚至可能成为系统的性能瓶颈,降低系统的可用性和吞吐量.提出分布式键值存储系统Elsa,这是一种面向跨区域架构的无协调键值存储系统. Elsa在保证高性能和高可拓展性的基础上,采用无冲突备份数据结构(CRDT)技术来无协调的保证副本间的强最终一致性,降低了系统节点间的协调开销.在阿里云上构建了跨4数据中心8节点的跨区域分布式环境,进行了大规模分布式性能对比实验,实验结果表明:在跨域的分布式环境下,对于高并发争用的负载, Elsa系统的性能具备明显的优势,最高达到MongoDB集群的7.37倍, Cassandra集群的1.62倍.

Elsa: Coordination-free Distributed KVS for Cross-region Architecture

As a distributed storage solution with high performance and high scalability, key-value storage systems have been widely adopted in recent years, such as Redis, MongoDB, Cassandra, etc. On the one hand,the multi-replication mechanism widely used in distributed storage system improves system throughput and reliability, but also increases the extra overhead of system coordination and replicationconsistency. For the cross-region distributed system, the long-distance replication coordination overhead may even become the performance bottleneck of the system, reducing system availability and throughput. The distributed key-value storage system called Elsa, proposed in this study, is a coordination-free multi-master key-value storage system that is designed for cross-region architecture. On the basis of ensuring high performance and high scalability, Elsa adopts the conflict-free replicated data types (CRDT) technology to ensure strong eventual consistency between replications without coordination, reducing the coordination overhead between system nodes. In this study, across-region distributed environment spanning 4 data centers and 8 nodes on aliyun platform is set up and a large-scale distributed performance comparison experiment is carried out.The experimental results show that under the cross-region distributed environment, the throughput of Elsa has obvious advantages for high concurrent contention loads, reaching up to 7.37 times of the MongoDB cluster and 1.62 times of the Cassandra cluster.