To improve the reliability of data storage systems, certain data placement schemes spread replicas across several nodes. This enables parallelizing the rebuild process which in turn results in reducing the rebuild times. However, the underlying assumption is that the parallel rebuild process is facilitated by sufficient availability of network bandwidth to transfer data across nodes. In a large-scale data storage system where the network bandwidth for rebuild is constrained, such placement schemes will not be as effective. In this paper, it is shown through analysis and simulation how the spread of replicas across nodes affects system reliability under a system network bandwidth constraint. Efficient placement schemes that can achieve high reliability in the presence of bandwidth constraints are proposed. Furthermore, in a dynamically changing storage system, in which the number of nodes and the network rebuild bandwidth can change over time, the data placement can be accordingly adapted to maintain the highest level of reliability.
An updated version of this report has been published in: Proc. 2012 IEEE 20th Int'l Symp. on Modelling, Analysis, and Simulation of Computer and Communication Systems "MASCOTS," Washington, DC (IEEE, August 2012) 189-197.
By: V. Venkatesan, I. Iliadis, R. Haas
Published in: RZ3821 in 2012
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