Client-aware cloud storage

Cloud storage is receiving high interest in both academia and industry. As a new storage model, it provides many attractive features, such as high availability, resilience, and cost efficiency. Yet, cloud storage also brings many new challenges. In particular, it widens the already-significant semantic gap between applications, which generate data, and storage systems, which manage data. This widening semantic gap makes end-to-end differentiated services extremely difficult. In this paper, we present a client-aware cloud storage framework, which allows semantic information to flow from clients, across multiple intermediate layers, to the cloud storage system. In turn, the storage system can differentiate various data classes and enforce predefined policies. We showcase the effectiveness of enabling such client awareness by using Intel's Differentiated Storage Services (DSS) to enhance persistent disk caching and to control I/O traffic to different storage devices. We find that we can significantly outperform LRU-style caching, improving upload bandwidth by 5x and download bandwidth by 1.6x. Further, we can achieve 85% of the performance of a full-SSD solution at only a fraction (14%) of the cost.