Data replication is a key technique to achieve high data availability, reliability, and optimized performance in distributed storage systems. In recent years, with emerged new storage devices, heterogeneous object-based storage systems, such as a storage system with a mix of hard disk drives, solid state drives, and other non-volatile memory devices have become increasingly attractive since they combine the merits of different storage devices to deliver better promises. However, existing data replication schemes do not well consider distinct characteristics of heterogeneous storage devices yet, which could lead to suboptimal performance. This article introduces a new data replication scheme called Pattern-directed Replication Scheme (PRS) to achieve efficient data replication for heterogeneous storage systems. Different from traditional schemes, the PRS selectively replicates data objects and distributes replicas to various storage devices based on their characteristics. It aggregates objects that have I/O correlation into object groups by calculating object distance and makes replication for grouped objects according to application's data access pattern identified. In addition, the PRS uses a pseudo random algorithm to optimize replica placement by considering the storage device performance and capacity features. We have evaluated the pattern-directed replication scheme with extensive tests in Sheepdog, a typical object-based storage system. The experimental results confirm that it is a highly efficient replication scheme for heterogeneous storage systems. For instance, the read performance was improved by 105 percent to nearly 10x compared with existing replication schemes.

中文翻译：

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PRS：基于对象的异构存储的模式导向复制方案

数据复制是在分布式存储系统中实现高数据可用性、可靠性和优化性能的关键技术。近年来，随着新的存储设备的出现，基于对象的异构存储系统，例如混合了硬盘驱动器、固态驱动器和其他非易失性存储设备的存储系统，由于它们结合了这些优点而变得越来越有吸引力。不同的存储设备，以提供更好的承诺。然而，现有的数据复制方案还没有很好地考虑异构存储设备的不同特性，这可能导致性能欠佳。本文介绍了一种新的数据复制方案，称为模式定向复制方案（PRS），以实现异构存储系统的高效数据复制。与传统方案不同，PRS 有选择地复制数据对象，并根据其特性将副本分发到各种存储设备。它通过计算对象距离将具有 I/O 相关性的对象聚合到对象组中，并根据识别的应用程序数据访问模式对分组对象进行复制。此外，PRS 使用伪随机算法通过考虑存储设备性能和容量特性来优化副本放置。我们已经在典型的基于对象的存储系统 Sheepdog 中通过广泛的测试评估了模式导向的复制方案。实验结果证实，它是一种高效的异构存储系统复制方案。例如，与现有复制方案相比，读取性能提高了 105% 至近 10 倍。