Reliability Analysis on Shifted and Random Declustering Block Layouts in Scale-Out Storage Architectures

Reliability is a critical metric in the design and development of scale-out data storage clusters. A general multiway replication-based declustering scheme has been widely used in enterprise large-scale storage systems to improve the I/O parallelism. Unfortunately, given an increasing number of node failures, how often a cluster starts losing data when being scaled-out is not well investigated. In this paper, we studied the reliability of multi-way declustering layouts by developing an extended model, more specifically abstracting the Continuous Time Markov chain to an ordinary differentiate equation group, and analyzing their potential parallel recovery possibilities. Our comprehensive simulation results on Mat lab and SHARPE show that the shifted declustering layout outperforms the random declustering layout in a multi-way replication scale-out architecture, in terms of data loss probability and system reliability by up to 63% and 85% respectively. Our study on both 5-year and 10-year system reliability equipped with various recovery bandwidth settings shows that, the shifted declustering layout surpasses the random declustering layout in both cases by consuming up to 5.2% and 11% less recovery bandwidth.