In a typical neighborhood, most essential services (e.g., power and phone lines, water pipes, gas and sewer lines) are hidden underground and out of sight. This collective plumbing provides the support infrastructure for daily living and becomes a focal point only when things don't work and disrupt daily living.

Just as essential services support the typical neighborhood, an underlying infrastructure provides the "plumbing" for data communications on your network. End users run a variety of applications to transact their daily business while assuming that the low-level infrastructure will provide stable and continuous service. Unfortunately, if that infrastructure fails and the network goes down, it disrupts daily business and costs companies money, sometimes into the millions of dollars. End users don't need to be aware of the infrastructure that's so essential to their business lives—it's the responsibility of network managers and engineers, who work behind the scenes, to ensure that both the high-level applications and the low-level infrastructure run smoothly.

Database applications, online transaction processing (OLTP), email, Web-based services, and other end-user applications require three basic components: computing platforms, network interconnect, and storage. Storage Area Networks (SANs) bring the storage component into the network's lower layers and let high-level applications share disk and tape resources. Because SANs are relatively new, the storage industry has initially focused on SAN infrastructures. Fibre Channel, Internet SCSI (iSCSI), IP-based SAN extension, storage virtualization, and other low-level matters receive considerable press coverage and cause heated debate among SAN vendors. Although this treatment might be a natural side effect of an emerging technology, all customers really want is reliable, high-performance data service: They want to know whether their applications will run efficiently and whether they'll have continuous access to their data.

Storage-related applications such as volume management, storage-resource management, server clustering, data replication, and tape-backup utilities benefit from a SAN's low-level performance and resource-sharing capabilities. However, the underlying transport should be transparent to these high-level applications. Regardless of whether a company bases its SAN infrastructure on Fibre Channel, iSCSI, or some combination of both, the customer should expect that the high-level applications will perform the same.

To create and maintain a transparent infrastructure, SAN hardware vendors need to develop hardware that satisfies the customer's expectations for standards compliance and fosters stability and interoperability. Consequently, customers in the market for SAN equipment typically have long laundry lists of standards that the equipment must meet before the customer can decide on a solution. By assuring standards compliance, the customer increases the odds that an acquisition won't create support and interoperability problems later.

Ironically, companies don't place standards-compliance criteria on high-level applications. Although running applications smoothly depends on a stable, standards-compliant network infrastructure, companies often use nonstandard, vendor-specific (e.g., VERITAS Software for backing up), or applications that vendors have tailored for a customer's business needs (e.g., Oracle provides modules that a customer can tailor to his or her own specific business requirements). Applications thus benefit from the rigor companies take to create sound infrastructure while providing the flexibility to adapt to specific customer requirements. The standards-compliance criteria that the customer places on the infrastructure enables the infrastructure to run smoothly. The applications themselves, however, might be proprietary, nonstandard, or created exclusively for a customer's use.