Informed storage management for mobile platforms

Abstract

Storage devices are rapidly changing, and we need to adapt the OS storage software stack to keep up with the changes. Such a re-evaluation of the storage software stack is especially required for mobile platforms because they are relying on inexpensive flash storage devices having very different performance characteristics from the familiar hard disk.In this thesis work, we first show the importance of storage in mobile platforms; contrary to conventional wisdom, we find evidence that storage is a significant contributor to application performance on mobile devices. Then, we explore the solution space for flash storage; user-level library for selective logging, host-side write buffering layer, and OS buffer replacement scheme for flash storage have been studied. Finally, we build an integrated solution for smartphone storage, named Fjord. In the Fjord study, we re-design logging and RAM buffering solutions for smartphones, and also propose fine-grained reliability control mechanisms. We prove that non-volatile logging can improve storage performance remarkably. Understanding the characteristics of cloud-backed applications and controlling the reliability constraint for chosen cloud-backed applications can achieve additional significant performance gain.We implement and evaluate our solution on a real Android smartphone, and demonstrate significant performance gains for everyday apps on such platforms.