IP SAN moves SAN beyond the glass house.

Fibre Channel SANs emerged in the late 1990s as the storage networking technology of choice for open systems servers in core corporate data centers (the glass house), providing a shared storage pool for a corporation's most important business applications. Today, the SAN revolution continues.

Now, the availability of TCP/IP-based SAN solutions has opened the door to the glass house and allowed SANs to move beyond it. It is not just an acquisition cost issue. It is also a combination of a familiar, mature network technology (i.e., TCP/IP and Gigabit Ethernet), lots of people with experience using it and performance levels which satisfy the requirements of the vast majority of enterprise applications.

In the days before SANs, data centers had no choice but direct-attached storage (DAS) for their open systems servers and had to suffer the consequences of tightly coupled server/storage solutions. Application data was associated with specific physical drives and center managers often found themselves with solutions that were oversubscribed, others that were underutilized and very few instances of balanced utility.

When the opportunity arose to uncouple the servers from the storage systems, everyone but the server vendors rejoiced. Yes, there was a premium to be paid for the Fibre Channel interface between the networked storage systems and the server. And, there was an added cost for the Fibre Channel savvy that people needed to make them play nicely together. But from an IT manager's perspective, those premiums were worth paying to achieve substantially better storage resource utilization and performance for their mission-critical enterprise applications.

Since the early days of SANs, we've seen progress in both Fibre Channel and in IP network technologies. What was once a decided bandwidth advantage for Fibre Channel has, with the advent of Gigabit Ethernet, become largely a moot point as very few applications require the incremental I/O performance advantage that Fibre Channel delivers. The parallel evolution of iSCSI was the final enabling event. It enabled block-mode storage over Ethernet and so began a new chapter in the evolution of storage area networks: IP SANs.

It is important to reiterate that this is more than just an acquisition-cost story. A commonly accepted metric is that over the economic life of a storage solution, management costs will be five times the initial acquisition cost. Given the prevalence and maturity of IP and Ethernet management applications and the number of IP-knowledgeable staff in most IT departments today, IT managers intuitively recognize the cost reduction opportunities inherent in management alone. Thus, it is economies of scale, coupled with the availability of IP-knowledgeable talent, plus the performance, reliability and robustness of standard networking technology, that are ushering in an era of new SAN deployments beyond the glass house.

IP SANs have already built up significant momentum, displacing DAS. This is occurring today primarily in regional and departmental data centers in very large organizations and in primary data centers in medium-sized organizations using lots of smaller (usually Intel architecture) servers. The data management problems inherent with DAS in these environments are obvious and painful. But Fibre Channel host adapters and switches represent a significant cost relative to that of the servers, in many instances even eclipsing those costs. Consequently, Fibre Channel SAN solutions have been impossible to justify. That's where IP SANs enter the picture, providing affordable storage consolidation and simpler, centralized data management.

Interestingly, the most popular enterprise applications used in these distributed data center environments continue to evolve in availability requirements, with downtime being viewed as a serious business risk. The "business critical" applications are now bordering on "mission-critical." IT managers are looking for the same kinds of data protection and disaster recovery capabilities here as in the glass house. IP SAN solutions can provide those capabilities today.

IP SAN solutions are also becoming popular for secondary storage, in both departmental data centers and the glass house. IP SAN secondary storage can provide a costeffective disk-based staging area for a Fibre Channel-based tape and backup infrastructure. The result extends both the economic life of perfectly suitable older Fibre Channel backup devices as well as the reach of these devices to a greater amount of application data without the constraints of the backup window.

Clearly, IP SAN solutions provide IT with more options for tackling cost, availability, performance and management issues resulting from continuing data growth, particularly in those environments outside the glass house. IP SAN solutions not only serve as a means for leaping from DAS to networked storage for primary storage, but also provide a solid option for extending the benefits of secondary storage in those same environments. IP SAN solutions will ultimately play an important part in integrating an enterprise's data assets across their global IT infrastructure.

For example, Independence Air, a low-fare airline servicing 42 destinations in the United States, replaced six existing DAS servers with a NetApp IP SAN infrastructure. The airline uses iSCSI technology to support critical applications such as Microsoft Exchange and SQL Server databases.

"Our Exchange and SQL Servers rely on NetApp storage just as if it were a local disk and we can take advantage of NetApp data management tools on the back end," said Chris Hughes, director of information technology for Independence Air. "In addition to enabling us to more efficiently utilize our storage resources, we have substantially improved e-mail availability for over 4000 users company wide. If a server fails, its database can be brought back online in seconds versus the hours it would take to restore it from tape. When you're coordinating flight schedules and business operations across nearly 40 sites, e-mail is a business critical tool."

NetApp storage simultaneously provides NAS storage to support key maintenance systems serving the entire Independence Air fleet. Independence Air credits NetApp with helping it meet aggressive goals for "on time" departures and arrivals by helping shrink maintenance windows with shorter batch processes on key systems.

As the airline continues to expand operations, the NetApp unified IP SAN and NAS solution provides the scalability and cost-effective reliability to support its growing business. Independence Air illustrates just one example of a company that realized the effectiveness and flexibility of an IP SAN to support its long-term business and storage needs across platforms, applications and geographies.

David Dale is industry evangelist, Network Appliance Chair, SNIA IP Storage Forum

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