Practical optimizations for lightweight distributed file system on consumer devices

Nowadays, household NAS service provides consumer device users a convenient way to extend their storage space through WLAN. As the core of NAS service, distributed file system’s objective is to make the whole system provide a good user experience. However, it is normal for consumer devices to work under unstable network conditions, which can significantly degrade the user experience. Moreover, user behavior is getting more complicated, which means traditional mainstream optimization techniques have little effect in this case. To improve user experience, this paper proposes several practical optimization solutions for a lightweight distributed file system. First, a set of client-side cache optimization schemes, including swap-based persistent caching and cross-device cache prefetching with the Markov method, are proposed to reduce remote access latency. Second, a task-aware write-back scheduling scheme is proposed to enhance the cache synchronization efficiency. Finally, a simple protocol based on multiple readers and single writer for multi-device access control is proposed. Experiments on real devices show that the average access latency can be reduced by 29.7% with swap-based client-side persistent caching. Cross-device prefetching reduces around 33% access latency in the best case. Average cache synchronization latency is reduced by 13.7% and the worst synchronization latency is reduced by 63.7% with write-back scheduling. Multi-device access protocol induced negligible overhead but works effectively on controlling concurrent accesses.