MDCC

Abstract

Replicating data across multiple data centers allows using data closer to the client, reducing latency for applications, and increases the availability in the event of a data center failure. MDCC (Multi-Data Center Consistency) is an optimistic commit protocol for geo-replicated transactions, that does not require a master or static partitioning, and is strongly consistent at a cost similar to eventually consistent protocols. MDCC takes advantage of Generalized Paxos for transaction processing and exploits commutative updates with value constraints in a quorum-based system. Our experiments show that MDCC outperforms existing synchronous transactional replication protocols, such as Megastore, by requiring only a single message round-trip in the normal operational case independent of the master-location and by scaling linearly with the number of machines as long as transaction conflict rates permit.

Geo-distribution of actor-based services

“…There has been a steady stream of papers in recent years on systems to support transactions over geo-distributed storage, using classical ACID semantics [Baker et al 2011;Corbett et al 2013], weaker isolation for better performance [Li et al 2012;Sovran et al 2011], and optimized geo-distributed commit protocols [Kraska et al 2013;Nawab et al 2013Nawab et al , 2015. Unlike Geo, they do not provide an actor model with user-defined operations, nor do they separate geo-distribution from durability.…”

Exactly-Once Quantity Transfer

“…To the best of our knowledge, no further improvements were made to the demarcation protocol, and it is still being used by current systems despite its aforementioned caveats [8], [9], [10], [11].…”

“…This allowed the propagation of any number of consecutive changes to be made without having to wait for acknowledgments. For these reasons, in addition to its simplicity, the demarcation protocol is still being used nowadays [8], [9], [10], [11]. However, the authors themselves admit that the protocol mis-behaves if no assumptions about message delivery are made.…”

Conflict-Free Replicated Data Types CRDTs

“…Internet-scale distributed systems often replicate data at multiple geographic locations to provide low latency and high availability, despite node and network failures. Some systems [25,48,28,41,75,52] adopt strong consistency models, where the execution of an operation needs to involve coordination of a quorum of replicas. Although it is possible to improve the throughput of these systems (e.g., through batching), the required coordination leads to high latency for executing one operation, that depends on the round-trip time among replicas and the protocol used.…”