RX-NAS: A Scalable, Reliable Clustered NAS System

RX-NAS (Replicated eXpandable Network-Attached Storage), a scalable, reliable clustered NAS system designed for entry-level NAS, has been developed. RX-NAS is based on X-NAS, which is a simple clustered NAS architecture for entry-level NAS, and improves the reliability of X-NAS by adding new sets of X-NASs to the original one. The core feature of RX-NAS, namely on-line replication, replicates original file objects to new sets of X-NASs for each file block in real-time without changing clients' environments. RX-NAS has other key features for maintaining the manageability of entry-level NAS; namely, new synchronization and resynchronization functions can easily replicate original files and directories to other X-NAS systems completely or partially without changing clients' environments. In addition, its health-check function can eliminate a limitation on the configuration of RX-NAS and detect and report errors that occur in the RX-NAS system. To validate the RX-NAS concept, an RX-NAS prototype was designed and tested according to the NFSv3 implementation. These tests show that the RX-NAS improves system reliability while maintaining 80% of the throughput of X-NAS.