Abstract: United storage network, which provides users with both File I/O and Block I/O, realizes the uniting of NAS and SAN. With the third party transfer protocol, USN achieves the following objectives: Managed centrally by a metadata server, USN can make users share its storage space dynamically, so USN is used effectively; felicitous distribution of credentials to users has realized the consistency of data sharing; using key distribution scheme to create credentials can provide security to USN without costing too much computation penalty of the metadata server; the separation of metadata channel from data channel improves USN I/O performance. All those have been tested by experiment

Key words: Network attached storage (NAS)；Storage area network (SAN)；United storage network (USN)；Third party transfer protocol

摘要： USN（统一存储网）为用户同时提供File I/O 和Block I/O 服务，实现了NAS 和SAN 的统一。采用三方传送协议实现USN 可以达到以下目的：元数据服务器集中管理存储设备实现了存储空间的动态共享，提高了存储空间的利用率；合理地分配信用保证了数据共享的一致性；利用密钥分配方案生成信用在保证存储安全的同时而不增加元数据服务器的过重的负担；元数据通道和数据通道的分离，提高了USN 的I/O 性能。实验证明该方法是可行的。

关键词: 附网存储；存储区域网；统一存储网；三方传送协议