NAS connectivity characterizes the real power of network storage. Connection directly to existing networks allows the NAS devices to function as network I/O managers. However, the ease of implementation within a network is a double-edged sword, providing administrators with an easy mode of implementation that masks the serious implications of the network storage traffic driven by NAS workloads. The use of Ethernet network topologies provides an effective and proven infrastructure when it comes to planning and implementing appliance, mid-range, and enterprise NAS solutions.
From a software perspective, the use of TCP/IP allows configuration and support to be easily integrated into existing IT knowledge and support structures. With the number of tools available to monitor networks and network infrastructures, the ability to manage the connectivity of NAS devices is far more advanced than any other storage networking methodology. However, the inherent nature of TCP/IP stack processing provides a challenging mix of performance and configuration issues once connectivity transfers from the network to the NAS server. These issues are still evolving as NAS workloads become more complex and network connectivity extends beyond the Ethernet and TCP/IP infrastructures .
Connectivity plays a very visible role as NAS devices become integrated into other storage systems. The evolution of storage networking is eliminating the boundaries between direct attach, Fibre Channel networks, and many sophisticated WAN configurations. Although many of these external connectivity issues will be addressed in Parts IV and V regarding integration with other storage models, we will discuss the effect and conditions surrounding LAN and WAN connectivity issues.