The end result is that when users and customers do not have access to data because of network downtime, the impact can be significant for company's performance. Downtime costs are not just pure people time, but transaction loss, loss of business, negative impact to customer satisfaction, and higher technical support costs. As these servers reach their storage potential, administrators have the choice of deploying more servers, which will compound their administrative overhead further-or implementing a storage resource that can scale massively and be shared by the various servers on the network. In addition, a shared storage resource lowers hardware and maintenance costs. Furthermore, the communications technology underpinning SANs affords higher availability.
SANs provide shared, scalable storage in a networked environment.
SANs can interconnect servers with storage arrays, tape libraries, or a mixture of these. Figure 1 shows an example of a SAN environment. Furthermore, SANS can provide a widely extensible architecture that enables servers and storage to be interconnected over vast distances of up to six miles or more. Central to SANs is a Fibre Channel switch or hub, which functions like a director, mapping requests and responses between the interconnected devices. Hubs provide a loop connection scheme that shares bandwidth between the interconnected devices.