Reliable Communication Infrastructure for Adaptive Data Replication (original) (raw)

Dynamic Replication Based on Availability and Popularity in the Presence of Failures

Journal of Information Processing Systems, 2012

The data grid provides geographically distributed resources for large-scale applications. It generates a large set of data. The replication of this data in several sites of the grid is an effective solution for achieving good performance. In this paper we propose an approach of dynamic replication in a hierarchical grid that takes into account crash failures in the system. The replication decision is taken based on two parameters: the availability and popularity of the data. The administrator requires a minimum rate of availability for each piece of data according to its access history in previous periods, but this availability may increase if the demand is high on this data. We also proposed a strategy to keep the desired availability respected even in case of a failure or rarity (nopopularity) of the data. The simulation results show the effectiveness of our replication strategy in terms of response time, the unavailability of requests, and availability

Adaptive Middleware for Data Replication

Lecture Notes in Computer Science, 2004

Dynamically adaptive systems sense their environment and adjust themselves to accommodate to changes in order to maximize performance. Depending on the type of change (e.g., modifications of the load, the type of workload, the available resources, the client distribution, etc.), different adjustments have to be made. Coordinating them is already difficult in a centralized system. Doing so in the currently prevalent component-based distributed systems is even more challenging. In this paper, we present an adaptive distributed middleware for data replication that is able to adjust to changes in the amount of load submitted to the different replicas and to the type of workload submitted. Its novelty lies in combining load-balancing techniques with feedback driven adjustments of multiprogramming levels (number of transactions that are allowed to execute concurrently). An extensive performance analysis shows that the proposed adaptive replication solution can provide high throughput, good scalability, and low response times for changing loads and workloads with little overhead.

2012-FGCS Journal-A survey of dynamic replication strategies for improving data availability.pdf

Data grid is a distributed collection of storage and computational resources that are not bounded within a geophysical location. It is a fast growing area of research and providing efficient data access and maximum data availability is a challenging task. To achieve this task, data is replicated to different sites. A number of data replication techniques have been presented for data grids. All replication techniques address some attributes like fault tolerance, scalability, improved bandwidth consumption, performance, storage consumption, data access time etc. In this paper, different issues involved in data replication are identified and different replication techniques are studied to find out which attributes are addressed in a given technique and which are ignored. A tabular representation of all those parameters is presented to facilitate the future comparison of dynamic replication techniques. The paper also includes some discussion about future work in this direction by identifying some open research problems. .pk (A. Daud).

Dynamic Object Replica Placement using Underlying Routing Protocols: Ensuring the Reliability

Object replication is an unavoidable phenomenon in distributed systems to address the issues of size, administrative and resources scalability. It also guarantees the availability of system as more users can be accommodated and failures can be tolerated. If the location of object replica is not proper, the problem may arise when it is requested by many entities at once. The response time may also increase due to the network latency although network is considered to be steadfast in the distributed systems but the latency can never be avoided. Efficient replica placement, both client initiated and server initiated, can be ensured using the dynamic replica placement mechanism in conjunction with the underlying routing protocols that provides the reliability of contents distribution and minimizes the network latency. In this paper, it is discussed that reliability can be assured if we use replica placement algorithm along with the EIGRP (Enhanced Interior Gateway Routing Protocol). The issues of choosing the best path for placing the replica that provides the minimum latency and reliability of contents transmission can be overcome by combining the EIGRP features that includes internetwork delay, bandwidth consumption, reliability of packet transmission and traffic load, with dynamic replica placement algorithm.

CAnDoR: Consistency Aware Dynamic data Replication

2019 IEEE 18th International Symposium on Network Computing and Applications (NCA), 2019

Data management has become crucial. Distributed applications and users manipulate large amounts of data. More and more distributed data management solutions arise, e.g. Casandra or Cosmos DB. Some of them propose multiple consistency protocols. Thus, for each piece of data, the developer or the user can choose a consistency protocol adapted to his needs. In this paper we explain why taking the consistency protocol into account is important while replication (especially placing) pieces of data; and we propose CAnDoR, an approach that dynamically adapts the replication according to the data usage (read/write frequencies and locations) and the consistency protocol used to manage the piece of data. Our simulations show that using CAnDoR to place and move data copies can improve the global average access latency by up to 40%.

Dynamic Object Replica Placement Using Underlying Routing Protocols: Ensuring Reliability

Managing Data Replication and Placement based on Availability

AASRI Procedia, 2013

The replication of data across multiple sites of data grid is an effective solution to achieve good performance in terms of load balancing, response time, and improving data availability. To get the maximum gain that can make the data replication, their placement strategy in the system is critical. This paper proposes a replication strategy based on availability. It proposes also a placement and replacement strategies of replicas that ensures the desired availability with the minimum replicas despite the presence of nodes failures and without overloading the system. The results of our experimentations confirm that the proposed approach reaches its objectives.

The performance of weak-consistency replication protocols

1992

Weak-consistency replication protocols can be used to build wide-area services that are scalable, fault-tolerant, and useful for mobile computer systems. We have developed the timestamped antientropy protocol, which provides reliable eventual delivery with a variety of message orderings. Pairs of replicas periodically exchange update messages; in this way updates eventually propagate to all replicas. In this paper we present a detailed analysis of the fault tolerance and the consistency provided by this protocol. The protocol is extremely robust in the face of site and network failure, and it scales well to large numbers of replicas. We are investigating an architecture for building distributed services that emphasizes scalability and fault tolerance. This allows applications to respond gracefully to changes in demand and to site and network failure. It also provides a single mechanism to support wide-area services and mobile computing systems. It uses weak-consistency replication techniques to build a flexible distributed service. We use data replication to meet availability demands and enable scalability. The replication is dynamic in that new servers can be added or removed to accommodate changes in demand. The system is asynchronous, and servers are as independent as possible; it never requires synchronous cooperation of large numbers of sites. This improves its ability to handle both communication and site failures. Eventually or weakly consistent replication protocols do not perform synchronous updates. Instead, updates are first delivered to one site, then propagated asynchronously to others. The value a server returns to a client read request depends on whether that server has observed the update yet. Eventually, every server will observe the update. Several existing information systems, such as Usenet [1] and the Xerox Grapevine system [2], use similar techniques. Delayed propagation means that clients do not wait for updates to reach distant sites, and the faulttolerance of the replicated data cannot be compromised by clients that misbehave. It also allows updates to be sent using bulk transfer protocols, which provide the best efficiency on high-bandwidth high-latency networks. These transfers can occur at off-peak times. Replicas can be disconnected from the network for a period of time, and will be updated once they are reconnected. On the other hand, clients must be able to tolerate some inconsistency, and the application may need to provide a mechanism to reconcile conflicting updates. Large numbers of replicas allow replicas to be placed near clients, and spread query load over more sites. This decreases both the communication latency for client requests and the amount of long-distance traffic that must be carried on backbone network links. Mobile computing systems can maintain a local replica, ensuring that users can use access information even when disconnected from the network. These protocols can be compared with consistent replication protocols, such as voting protocols. Consistent protocols cannot practically handle hundreds or thousands of replicas, while weak-consistency protocols can. Consistent protocols require the synchronous participation of a large number of replicas, which can be impossible when a client resides on a portable system or when the network is partitioned. It is also difficult to share processing load across many replicas. The communication traffic and associated latency are often unacceptably large for a service with replicas scattered over several continents.

Design and analysis of an adaptive object replication algorithm in distributed network systems

Computer Communications, 2008

In this paper, we propose an adaptive object replication algorithm for distributed network systems, analyze its performance from both theoretical and experimental standpoints. We first present a mathematical cost model that considers all the costs associated with servicing a request, i.e., I/O cost, control-message transferring cost, and data-message transferring cost. Using this cost model, we develop an adaptive object replication algorithm, referred to as Adaptive Distributed Request Window (ADRW) algorithm. Our objective is to dynamically adjust the allocation schemes of objects based on the decision of ADRW algorithm, i.e., whether the system is read-intensive or write-intensive, so as to minimize the total servicing cost of the arriving requests. Competitive analysis is carried out to study the performance of ADRW algorithm theoretically. We then implement our proposed algorithm in a PC based network system. The experimental results convincingly demonstrate that ADRW algorithm is adaptive and is superior to several related algorithms in the literature in terms of the average request servicing cost.

Dynamic management of highly replicated data

1992

We prescnt an efficient replication control protocol for managing replicated d a u objects that have more th' an five replicas. Like the grid protocol, our dynamic group protocol requires only ~( d n )

Reliable Communication Infrastructure for Adaptive Data Replication (original) (raw)

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