Network storage has been moving closer and closer to the center stage of information system in the recent years as performance, availability, scalability, innovation, and ease of use become more and more important to businesses. At the systems level, there are two emerging network storage architectures: the storage area network (SAN) and network-attached storage (NAS). In different ways, these two architectures aim to improve access to data by more than one application or user. Both architectures exp loit the availability of high-speed networking. SAN and NAS products also may offer built- in utilities for backup and replication (mirroring). SAN architectures address the need to consolidate large amounts of enterprise data by designing dedicated high-speed fiber networks. NAS products plug into existing LANs to provide convenient and low-cost additional storage, ranging from a few gigabytes for a home network to terabytes for enterprise systems.