Fjord: Informed storage management for smartphones

Smartphone applications are becoming more sophisticated and require high storage performance. Unfortunately, the OS storage software stack is not well engineered to support flash-based storage used in smartphones. On top of that, storage software stack is configured to be too conservative due to the fear of sudden power failures. We believe that this conservatism with respect to data reliability is misplaced considering that many of the popular apps (e.g., Web browsing, Facebook, Gmail) that run on today´s smartphones are cloud-backed, and the local storage on the smartphone is often used as a cache for cloud data. In this paper, we propose Informed Storage Management framework, named Fjord, for mobile platforms. The key insight is to use system-wide dynamic context information to improve the storage performance on mobile platforms. We implement a set of mechanisms (write buffering, logging, and fine-grained reliability control), and through judicious use of these mechanisms based on system context, we show how we can achieve significant improvement in storage performance. As proof of concept, we implement Fjord in two Android smartphones and experimentally validate the performance advantage of informed storage management with multiple smartphone applications.