Cegor: an adaptive distributed file system for heterogeneous network environments

Distributed file systems have been extensively studied in the past, but they are still far from wide acceptance over heterogeneous network environments. Most traditional network file systems target the tight-couple highspeed networks only, and do not work well in the wide-area setting. Several communication optimization techniques are proposed in the context of wide-area file systems, but these approaches do not take into consideration the file characteristics and may instead introduce extra computing overhead when the network condition is good. We envision that the capability of providing adaptive, seamless file access to personal documents across diverse network connections plays an important role in the success of future distributed file systems. In this paper, we propose to build an adaptive distributed file system which provides the "close and go, open and resume" (Cegor) semantics across heterogeneous network connections, ranging from high-bandwidth local area network to low-bandwidth dial-up connection. Our approach relies on a set of new techniques for managing adaptive access to remote files, including three components: system support for secure, transparent reconnection at different places, semantic-view based caching to reduce communication frequencies in the system, and type-specific communication optimization to minimize the bandwidth requirement of synchronizations between clients and servers.