Copy rate synchronization with performance guarantees for work consolidation in storage clusters

As storage in data centers is increasing rapidly, it has become critical to find ways to operate efficiently this important component of a data center. Often, it has been proposed to consolidate the storage workload into a subset of storage devices and shutdown the unused ones with the purpose of preserving power. In many cases storage workload consolidation requires some amount of data to be copied from one device or set to the next. While storage workload consolidation techniques focus on extending power savings with minimal penalty in the performance of a data center, less attention is paid to the process of seamlessly integrating the data copy phase into the overall storage workload consolidation technique. Specifically, in this paper, we propose an analytic framework that synchronizes the pace of copying data between two storage devices (or nodes) such that performance is maintained within predefined targets. As such, we avoid either undesired performance degradation caused by aggressively scheduling the data copy task or a slow copy process caused by conservative scheduling. We show with extensive experimentation that the framework is robust and that it provides an important step toward automating storage consolidation and high power savings.