The Taub Faculty of Computer Science Events and Talks

Smart-phones are quickly becoming the most prevalent computing and communication devices. As the capabilities of these mobile phones improve as well as our reliance on them, backing up the data stored on the phone becomes vital. Typical cloud based backup services assume reliable high bandwidth connection to the Internet. This assumption, however, in not practical in many places, which motivates the need for ad-hoc cloud services, and in particular, for a social storage service that can be used to backup important files. This work describes the design and implementation of such a system for the Android operating system. It enables backing up files in devices that are encountered on a regular basis. The design of the system is modular, and includes mechanisms for detecting and identifying regular social encounters as well as file accesses. Based on these, the system decides which file should be replicated and to which other devices. The system also includes a recovery mechanism that enables restoring a missing file as well as the entire set of files, e.g., in case the device's storage unit got damaged, or the phone was destroyed or got stolen. The work is calibrated and validated using publicly available encounter traces as well as synthetic traces. Performance measurements on contemporary smart-phones, including latency to backup and restore a file, CPU load, and power consumption, are also presented.