Toward Reconciling Availability, Consistency and Integrity in Replicated Information Systems (original) (raw)

Trying to Cater for Replication Consistency and Integrity of Highly Available Data

2006

Availability of databases benefits from distributed replication. Each application and user require different degrees of data availability, consistency and integrity. The latter are perceived as competing objectives that need to be reconciled by appropriate replication strategies. We outline work in progress on a replication middleware architecture for distributed databases. It simultaneously maintains several protocols, so that it can be reconfigured on the fly to the actual needs of availability, consistency and integrity of possibly simultaneous applications and users.

Understanding replication in databases and distributed systems

Proceedings 20th IEEE International Conference on Distributed Computing Systems, 2000

Replication is an area of interest to both distributed systems and databases. The solutions developed from these two perspectives are conceptually similar but differ in many aspects: model, assumptions, mechanisms, guarantees provided, and implementation. In this paper, we provide an abstract and "neutral" framework to compare replication techniques from both communities in spite of the many subtle differences. The framework has been designed to emphasize the role played by different mechanisms and to facilitate comparisons. With this, it is possible to get a functional comparison of many ideas that is valuable for both didactic and practical purposes. The paper describes the replication techniques used in both communities, compares them, and points out ways in which they can be integrated to arrive to better, more robust replication protocols.

Consistent Replication in Distributed Multi-Tier Architectures

Proceedings of the 7th International Conference on Collaborative Computing: Networking, Applications and Worksharing, 2011

Replication is commonly used to address the scalability and availability requirements of collaborative web applications in domains such as computer supported cooperative work, social networking, e-commerce and e-banking. While providing substantial benefits, replication also introduces the overhead of maintaining data consistent among the replicated servers. In this work we study the performance of common replication approaches with various consistency guarantees and argue for the feasibility of strong consistency. We propose an efficient, distributed, strong consistency protocol and reveal experimentally that its overhead is not prohibitive. We have implemented a replication middleware that offers different consistency protocols, including our strong consistency protocol. We use the TPC-W transactional web commerce benchmark to provide a comprehensive performance comparison of the different replication approaches under a variety of workload mixes.

Boosting the Availability of Information Systems by Data Replication

2006

High availability of information in medium and large-sized enterprises may naturally benefit from a wide-area replication of data. We feature and discuss an ongoing development of replication architecture innovations. They boost the availability of business data in distributed information systems.

Enhancing the Availability of Networked Database Services by Replication and Consistency Maintenance

2003

We describe an operational middleware platform for maintaining the consistency of replicated data objects, called COPla (Common Object Platform). It supports both eager and lazy update propagation for replicated data in networked relational databases. The purpose of replication is to enhance the availability of data objects and services in distributed database networks. Orthogonal to recovery strategies of backed-up snapshots, logs and other measures to alleviate database downtimes, COPla caters for high availability during downtimes of parts of the network by supporting a range of different consistency modes for distributed replications of critical data objects.

A Three-tier Active Replication Protocol for Large Scale Distributed Systems

IEICE TRANSACTIONS on Information and Systems, 2003

SUMMARY The deployment of server replicas of a service across an asynchronous distributed system (e.g., Internet) is a real practical challenge. This target cannot be indeed achieved by classical software replication techniques (e.g., passive and active replication) as these techniques usually rely on group communi- cation toolkits that require server replicas to run over a partially synchronous distributed system to solve the underlying agreement problem. This paper proposes a three-tier architecture for soft- ware replication that encapsulates the need of partial synchrony in a specific software component of a mid-tier to free replicas and clients from the need of underlying partial synchrony as- sumptions. Then we propose how to specialize the mid-tier in

Replication, consistency, and practicality

ACM SIGMOD Record, 1998

Previous papers have postulated that traditional schemes for the management of replicated data are doomed to failure in practice due to a quartic (or worse) explosion in the probability of deadlocks. In this paper, we present results of a simulation study for three recently introduced protocols that guarantee global serializability and transaction atomicity without resorting to the two-phase commit protocol. The protocols analyzed in this paper include a global locking protocol [lo], a "pessimistic" protocol based on a replication graph [5], and an "optimistic" protocol based on a replication graph [7]. The results of the study show a wide range of practical applicability for the lazy replica-update approach employed in these protocols. We show that under reasonable contention conditions and sufficiently high transaction rate, both replication-graph-based protocols outperform the global locking protocol. The distinctions among the protocols in terms of performance are significant.

The Performance of Available Copy Protocols for the Management of Replicated Data

Performance Evaluation, 1990

Available copy protocols guarantee the consistency of replicated data objects against any combination of non-Byzantine failures that do not result in partial communication failures. While the original available copy protocol assumed instantaneous detection of failures and instantaneous propagation of this information, more realistic protocols that do not rely on these assumptions have been devised. Two such protocols are investigated in this paper: a naive available copy (NAC) protocol that does not maintain any state information, and an optimistic available copy (OAC) protocol that only maintains state information at write and recovery times. Markov models are used to compare the performance of these two protocols with that of the original available copy protocol. These protocols are shown to perform nearly as well as the original available copy protocol, which is shown to perform much better than quorum consensus protocols.

A Flexible Hybrid Approach to Data Replication in Distributed Systems

Bokhari, Syed Mohtashim Abbas, and Oliver Theel. "A flexible hybrid approach to data replication in distributed systems." Intelligent Computing: Proceedings of the 2020 Computing Conference, Volume 1. Springer International Publishing, 2020, 2020

Data replication plays a very important role in distributed computing because a single replica is prone to failure, which is devastating for the availability of the access operations. High availability and low cost for the access operations as well as maintaining data consistency are major challenges for reliable services. Since failures are often inevitable in a distributed paradigm, thereby greatly affecting the availability of services. Data replication mitigates such failures by masking them and makes the system more fault-tolerant. It is the concept by which highly available data access operations can be realized while the cost should be not too high either. There are various state-of-the-art data replication strategies, but there exist infinitely many scenarios which demand designing new data replication strategies. In this regard, this work focuses on this problem and proposes a holistic hybrid approach towards data replication based on voting structures.