Designing Storage Area Networks: A Practical Reference for Implementing Fibre Channel and IP SANs (2nd Edition)

The historical trend of successful information technologies is toward ubiquitous deployment, enhanced functionality, and lower total cost of acquisition and operation; or, put simply, more, better, and cheaper. The Internet, for example, would not be possible without uniform and affordable technologies such as IP presentation and transport protocols, low-cost computing platforms, routed infrastructures, and ubiquitous and affordable access services (Ethernet, DSL, dial-up, and so on). At the same time, convergence does not automatically eliminate diversity. Voice over IP is gaining momentum for enterprise use but is still a minority application compared with legacy telephony systems. For voice over IP to displace classical telephony, it must meet these three basic criteria for successful technology evolution.

Ethernet began as a rather difficult and expensive technology requiring thick coaxial cable with limited distance and device support and was deployed primarily on midrange computing systems. In a fairly short time, it was adapted to thin coax cable and then to unshielded twisted-pair wiring, making it much more economical to deploy. When the functionality of Ethernet was enhanced by Ethernet switching, the increase in link speed from 10Mbps to 100Mbps gave Ethernet a clear performance advantage over the competing technologies of Token Ring and FDDI. The proliferation of Ethernet products simultaneously drove down the cost, eventually pushing the technology into the home at the low end while making it ubiquitous throughout enterprise networks. Just as widespread deployment drives down cost, lower costs accelerate widespread deployment. Pervasive adoption also fosters technology enhancement, and enhancements validate the viability of further deployments. More, better, cheaper becomes an escalating and ever-expanding circle of technology renewal.

Storage networking temporarily defied this evolutionary process by maintaining high margins on storage systems and interconnections, making only moderate improvements in interoperability and management, and targeting high-end enterprises with large budgets. SANs would thus be marginalized to top-tier enterprise networks were it not for the introduction of IP storage transports and more affordable storage targets based on ATA/IDE. These innovations preserve the basic value proposition of SANs in terms of resource sharing, consolidation, availability, and data archiving, but they build SANs on products that are easily acquired and supported.

The merger of SANs with mainstream networking, both for local data center applications and for distributed or wide area requirements, eventually leads to commoditization of storage networking, the bane of storage vendors and solutions providers. Instead of a captive market that can command premium pricing, vendors will find themselves in an open market driven by volume and volume pricing. Far from inhibiting improvement in functionality and quality, the mass market actually drives enhancements to differentiate one product from another. PCs, for example, now have much richer functionality and capabilities with each succeeding generation, with higher functionality available at a fraction of the previous cost point. As volumes increase and prices drop, customers benefit at the expense of vendor margins. Vendors in turn maintain profitability only by expanding market penetration, pulling more money from a wider customer base.

The appropriate analogy for what is currently happening to SAN technology is the shared printer networking market of the 1980s. For some time, sharing of printer resources was an art requiring special equipment, skills, and software. Vendors at the time made high margins at the expense of the customers' desire to streamline corporate printing operations. Salespeople sent their kids to college, paid their mortgages, and bought cars, sailboats, and other perks of deal closing, all on the basis of networked printer access. In less than a decade, however, networked printers became commoditized, with PC-attached sharable color printers now priced at less than $100. In the meantime, printer technology experienced a dramatic improvement in speed and capability. Fast laser and color inkjet printers with integrated Windows device driver support, high-resolution color photo quality, and support for multiple paper formats are sold by the pallet-load at Costco and other bulk outlets. Whether via Ethernet or USB interface, these devices can be readily shared in an enterprise or home network and either are automatically discovered by the operating system or can be easily configured by any literate end user.

What happened to the complexity of printer sharing that initially enabled such high margins? It was subsumed by printer interfaces and host systems, became embedded in silicon, or was handled by device drivers and configuration wizards. The complexity did not disappear; it disappeared only from view of the customer. Consequently, there is no equivalent to the high-priced SAN consultant or architect in today's mainstream shared printer market, and no Printer Networking Industry Association (PNIA) to coordinate the technological and marketing initiatives of printer vendors. The enormous success of shared printing has stripped it of its former elevated status and has democratized it throughout information technology, thus expanding the foundation of information technology as a whole by absorbing the solutions opportunistically created to serve it.

The integration of SANs into mainstream data communications does not eliminate diversity in product offerings or abolish the need for high-end solutions. The delta between high-end and midrange or between midrange and low-end, however, is less pronounced as vendors attempt to capture greater market share. Absorbing volume and resource management capabilities into an operating system, for example, deprives the third-party volume management vendors of their former monopoly and forces them to innovate by differentiating value-added functionality. RAID arrays that provide the sophistication of high-end systems but employ much lower-cost ATA technology force vendors of high-end storage to enhance their systems to maintain competitiveness. Low-cost SAN bridges that accommodate commodity disks while providing basic storage pooling capability help to drive greater intelligence into higher-end products while maintaining competitive pressure to keep pricing in check. Overall, the pricing commanded by the entire spectrum of solutions gradually falls, while the functionality offered at each level increases. The trend of technology to more, better, and cheaper products thus enhances SAN solutions over time and enables a broader market to share the benefits of storage networking.