On Consistency Of Data In Structured Overlay Networks

Shafaat, Tallat M.; Moser, Monika; Ghodsi, Ali; Schütt, Thorsten; Haridi, Seif; Reinefeld, Alexander

doi:10.1007/978-0-387-09457-1_21

Cited by 6 publications

(7 citation statements)

References 14 publications

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“…A similar bandwidth consumption-convergence time trade-o↵ is added by ReCircle [23], in the form of a partition-merger. ReCircle has two parts: a PS algorithm and a Merger.…”

Section: Overlay Maintenance Strategiesmentioning

confidence: 99%

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Reversible Phase Transitions in a Structured Overlay Network with Churn

2016

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Abstract. Distributed applications break down when the underlying system has too many node or communication failures. In this paper, we propose a general approach to building distributed applications that lets them survive hostile conditions such as these failures. We extend an existing Structured Overlay Network (SON) that hosts a transactional replicated key/value store to be Reversible, i.e., it is able to regain its original functionality as the environment hostility recedes. For this paper we consider the environment hostility to be measured by the Churn parameter, i.e., the rate of node turnover (nodes failing and being replaced by new correct nodes). In order to describe the qualitative behavior of the SON at high churn, we introduce the concept of Phase of the SON. All nodes in a phase exhibit the same qualitative properties, which are di↵erent for the nodes in di↵erent phases. We demonstrate the existence of Phase Transitions (i.e., a significant fraction of nodes changes phase) as churn varies and show that our concept of phase is analogous to the macroscopic phase of physical systems. We empirically identify the Critical Points (i.e., when there exists more than one phase simultaneously in significant fractions of the system) observed in our experiments. We propose an API to allow the application layer to be informed about the current phase of a node. We analyze how the application layer can use this knowledge for self-adaptation, self-optimization and achieve reversibility in the application-level semantics.

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“…A similar bandwidth consumption-convergence time trade-o↵ is added by ReCircle [23], in the form of a partition-merger. ReCircle has two parts: a PS algorithm and a Merger.…”

Section: Overlay Maintenance Strategiesmentioning

confidence: 99%

“…In some runs we have observed partition of the system after the isolated nodes complete their join procedures. For these scenarios, the PL approach used in [23] fails to trigger the merging. In order to merge such partitions proactive merger using KB is required.…”

Section: Reversibility and Its Evaluationmentioning

confidence: 99%

Reversible Phase Transitions in a Structured Overlay Network with Churn

2016

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“…The multiple hash function scheme [6] uses f hash functions for maintaining replication with degree f. The leafset and successor-set schemes [3,5] store replicas on respective nodes from routing tables of a node responsible for data item. In symmetric replication [4,7] replicas are stored under system-wide known f identifiers. Although there are qualitative differences between the named schemes, none regards the geographical location of nodes.…”

Section: A Replication In Sonsmentioning

confidence: 99%

Availability of Data in Locality-Aware Unreliable Networks

Geibig

2009

2009 Second International Conference on Advances in Mesh Networks

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The goal of our research is to improve data availability in large-scale wireless networks in a disaster scenario, where spatially correlated group of nodes may fail. In this paper, we analytically evaluate the efficacy of existing replication schemes from structured overlay networks under relaxed system constraints. The analysis shows that these schemes do not guarantee data survivability under the assumption of massive node crashes.

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“…Once network partitions cease, CATS merges partitioned subsystems into a single overlay, while Scatter will continue to operate as separate overlays. Where Scatter provides scalability and consistency, CATS provides scalability, consistency, and partition tolerance.The design, implementation, and evaluation of CATS are available in a separate technical report [3,2,20]. …”

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confidence: 99%

“…The design, implementation, and evaluation of CATS are available in a separate technical report [3,2,20].…”

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confidence: 99%

Cats

Arad

Shafaat

Haridi

2013

Proceedings of the 4th Annual Symposium on Cloud Computing

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Distributed key-value stores provide scalable, faulttolerant, and self-organizing storage services, but fall short of guaranteeing linearizable consistency in partially synchronous, lossy, partitionable, and dynamic networks, when data is distributed and replicated automatically by the principle of consistent hashing [14]. This work introduces consistent quorums as a solution for achieving atomic consistency. We present the design and implementation of CATS, a key-value store which uses consistent quorums to guarantee linearizability and partition tolerance in such adverse and dynamic network conditions. CATS is scalable, elastic, and self-organizing; key properties for modern cloud storage middleware. Our system evaluation shows that consistency can be achieved with practical performance and modest overhead: 5% decrease in throughput for read-intensive workloads, and 25% throughput loss for write-intensive workloads. CATS delivers submillisecond operation latencies under light load, single-digit millisecond operation latencies at 50% load, and it sustains a throughput of one thousand operations per second, per server, while scaling linearly to hundreds of servers.Distributed key-value stores, such as Cassandra [15] and Dynamo [8], employ principles from DHTs [21] to build scalable and self-managing data stores. In contrast to CATS, these systems chose availability over atomic consistency, hence only providing eventual consistency [22]. While eventual consistency is sufficient for some applications, the complexities of merging divergent replicas can be non-trivial. We avoid the complexities entailed by eventual consistency while providing scalable storage for critical applications which need atomic consistency, guaranteeing it at the cost of a modest decrease in throughput. To handle dynamic networks, atomic registers were extended by protocols such as RAMBO [17], RAMBO II [9], RDS [7] and DynaStore [1] to be reconfigurable. Similarly, SMART [16] enabled reconfiguration in replicated state machines.With consistent quorums we provide high-throughput read/write operations without paying the full cost of state machine replication which needs coordination for every operation. Moreover, our design does not depend on electing a single leader and the complexities that come with that [5]. While these systems can handle dynamism and provide atomic consistency, they are not scalable as they were not designed to partition the data across a large number of machines. The novelty of CATS is in extending the reconfiguration techniques contributed by these works, such that they can be used at large scale, in order to build a system that is completely decentralized and self-managing.Distributed coordination systems such as Chubby [4] and ZooKeeper [11,13], provide linearizability and crashrecovery, but are not scalable. Master-based key-value stores, such as Bigtable [6], HBase [12], and MongoDB [18], rely on a central server for coordination and data partitioning. Similarly, Spinnaker [19] uses Zookeeper [11]. Since these system...

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On Consistency Of Data In Structured Overlay Networks

Cited by 6 publications

References 14 publications

Reversible Phase Transitions in a Structured Overlay Network with Churn

Reversible Phase Transitions in a Structured Overlay Network with Churn

Availability of Data in Locality-Aware Unreliable Networks

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