Atsushi Ebata

Concept and evaluation of X-NAS: a highly scalable NAS system

X-NAS (expandable network attached storage), a highly scalable, distributed file system designed for entry-level NAS, has been developed. It virtualizes multiple NAS systems into a single-file-system view for different kinds of clients. The core of X-NAS is a multi-protocol virtualized file system (MVFS), and its key features - a smart-code wrapper daemon, file-group mapping, and a file-handle cache - improve X-NAS scalability. X-NAS has other key features for improving the manageability on many NAS systems; namely, on-line reconfiguration, autonomous rebalancing, and automatic migration, in which files are migrated automatically and dynamically independently of file-sharing services for clients. To validate the X-NAS concept, an X-NAS prototype was designed and tested according to the NFSv2 implementation. These tests indicate that X-NAS attains a quicker response time and higher throughput than a conventional single NAS, so its cost-performance scalability is also higher.