After a slow and sometimes painful start, storage networking has emerged from a long phase of standards development and interoperability testing to affirm its value for enterprise networks. The volume of shipments of Storage Area Network (SAN) solutions by major providers and by the new storage applications that SAN technology has enabled marks storage networking's success. Storage networking is now the prerequisite for a variety of business applications, including high-availability server clusters, storage consolidation, data backup, and disaster recovery. Supporting such applications would be difficult without the flexible access that storage-networking technology gives to servers, storage, and tape devices.
Although companies have productively deployed these SAN applications to solve customer problems, SAN adoption has been generally limited to the top-tier enterprise networks. Aside from the higher costs storage networking demands, the complexity of SANs and scarcity of skilled support for design and management of SAN systems have raised barriers to customer adoption. SANs evolved as a distinct network, not only physically separate from mainstream data-communication networks, but technologically separate as well. Until the development of IP-based storage networking, SANs based on fibre channel lacked the ability to integrate into the more familiar and more manageable enterprise data networks based on TCP/IP, making it difficult for the bulk of the potential market to enjoy the benefits SANs provide.
Two unrelated technologies are addressing the complexity associated with SANs: storage virtualization and IP storage networking. In combination, these two initiatives might bring SANs into mainstream networking and facilitate more widespread adoption. Virtualization doesn't eliminate the complexity of SAN infrastructures but hides it behind an automated intelligence. If virtualization can make disparate physical-storage resources appear as a self-managing logical storage resource, then users need less time and fewer skills to associate storage with the applications that require it. Although the ultimate goal of application-aware, self-allocating virtual storage will take some time to achieve, storage virtualization promises to do for storage what graphical interfaces have done for applications. Less management leads to reduced overhead and higher productivity, and consequently to lower total cost of ownership (TCO).
As storage virtualization continues to evolve, new IP storage technologies are bringing SANs into mainstream data networks and into the hands of a much broader market. The IP storage initiative is roughly divided into IP-only solutions such as Internet SCSI (iSCSI) and migration solutions such as Internet Fibre Channel Protocol (iFCP) that connect existing fibre channel SANs to IP network backbones. In either case, the customer can leverage familiar and more easily supported IP infrastructures to support both messaging and storage applications. In addition, the massive engineering and financial resources behind IP internetworking have already established Quality of Service (QoS) and security mechanisms that we can now apply to sensitive storage data. As the Promontory Project recently demonstrated (see URL below), IP storage is highly extensible and can transport storage data at gigabit speeds over coast-to-coast connections. This capability lets us implement shared storage regardless of distance or speed requirements.
The combination of IP storage and storage virtualization aligns storage networking to the common requirements of all customers to reduce costs, minimize overhead, streamline administration, and make storage simply an additional component in their overall network strategies. Just as printer networking stopped being a separate entity after shared print resource technology matured, storage networking will fold into conventional IP networking as it becomes easier to manage and deploy. In the future of storage networking, SANs become less distinct as they merge into the mainstream. As with networked printers, networked storage won't disappear from view but will become more ubiquitous and productive for all customers.