With the emergence of SANs (storage area networks) we no longer have to accept an inferior approach to storage infrastructure. A SAN provides a high-speed storage network that is not only extremely scalable but is designed for uncompromising availability.

Several forces are driving the SAN market. Most obvious is the explosive data growth with which many organizations are now wrestling. In the past year, the total amount of shipped disk storage doubled from around 700,000 TB to more than 1.4 million TB. With no end in sight for this high storage growth, the FibreAlliance, the FCIA (Fibre Channel Industry Association) and other organizations project that by 2002 the Fibre Channel market will surpass $2.4 billion.

Parallel to this storage growth, companies are seeking a way to manage the effects of these growth patterns. With a SAN's inherent scalability, organizations can shift storage management from a reactive strategy to a proactive one. As evidenced by the recent trend toward server clustering, a SAN will be practically mandated. Unless a SAN is running on the back end, the server cluster is severely limited in its ability to scale.

Other driving forces toward SANs include both HA (high availability) and disaster recovery. With a central storage pool, there is no need to replicate data across servers. If a server crashes, a secondary server can be brought online seamlessly, with full access to the exact data store. Furthermore, additional storage pools can be brought online and datasets rebuilt without hindering server performance. With a robust SAN infrastructure, concerns over HA are addressed with a mesh of fiber interconnects that remove points of failure in the storage subsystem.

Who should install a SAN? This decision requires careful consideration, as well as educated speculation, about current and future storage requirements. If you expect your storage requirements to exceed 1 TB, consider installing a SAN. With the distinct advantages of flexibility and the capacity to mold storage configurations, fiber-attached storage also can help accommodate future growth of emerging and smaller companies. Such storage affords the flexibility needed for a company to migrate to a SAN rather than play the SCSI-attached catch-up game.

In addition to the appeal of high disk availability, SANs become increasingly attractive when we consider the benefit of high-speed consolidated tape backup. Maintaining and managing a distributed network of SCSI-attached tape libraries is both expensive and a headache. These distributed tape libraries rarely mimic the storage requirements of the data they back up. Whether they're underused, wasting backup capacity, or overused, increasing the size of your backup windows, they're not going to be configured optimally. With a fiber-attached tape library, centralizing data lets you formulate an aggregate backup scheme that makes capacity planning more efficient and maximizes your capital investment. As with disk storage, the ability to scale the backup pools dynamically and allocate internal tape drives and capacity into virtual backup pools make data management more robust and efficient.

Our RFP

To get a sense of today's SAN solutions, we distributed an RFP for MediaMasters, our fictitious publishing company. Since its inception, MediaMasters has used a server-centric approach to address its storage needs. By continually enlarging the server storage pools on each of the separate servers and keeping up with evolving SCSI technology, MediaMasters has maintained operations. System backups and server-to-server and server-to-workstation file transfers have been performed over MediaMasters' switched 10-Mbps network. Because of the company's rapid growth, however, MediaMasters has begun to experience network bottlenecks from the increased number and size of files being shared. These bottlenecks are hurting productivity, so a solution is imperative.

MediaMasters considered two alternatives: Gigabit Ethernet and a SAN. In that MediaMasters sends large files--upward of 5 GB--over the wire, the chosen solution would need a high capacity to keep pace. Although high-speed Gigabit Ethernet offers many benefits for the LAN, this technology isn't adequate for MediaMasters' back-end storage needs. Both Gigabit Ethernet and Fibre Channel commonly support 100 MB per second. A detailed look at Gigabit Ethernet reveals some inherent weaknesses, however. Sending large files over the LAN is less efficient because Gigabit Ethernet is limited to a maximum packet size of 1,518 bytes. These small packets would cause a large-file transfer to throttle the servers with all the interrupts and overhead for packet processing. Fibre Channel, on the other hand, is based on frames rather than packets and can cluster a sequence of frames into a single block as large as 128 MB. The larger blocks reduce the number of interrupts and packet processing.

MediaMasters not only requires a high-performance back end, it also calls for this performance to be delivered to the workstations. In addition to the transfer issues, Gigabit Ethernet does not address storage consolidation or management issues that a SAN would handle well. It became apparent that Gigabit Ethernet complements a SAN in delivering content to the desktop; however, MediaMasters' immediate needs call for a high-speed back end to deliver all the way to the front end. With this knowledge, MediaMasters has chosen to implement a SAN.

Like many businesses, MediaMasters is a 24x7 company and relies on the guaranteed availability of its servers and accompanying storage. As a publisher of CD-ROMs, DVDs and interactive media, MediaMasters also requires a pipe fast enough to transfer large files across its storage systems and workstations. To achieve the highest availability, we asked vendors to provide a fault-tolerant solution that minimizes points of failure across the entire SAN. We suggested the vendors design their SANs with scalability and performance in mind, and listed no price cap for this RFP.

MediaMasters' network consists of three virtually identical buildings, each of which contains a different department. Two of the buildings reside on a corporate campus, and the third resides in a new office subdivision five miles away. Each building has four production servers. Three act as file servers, and the fourth is a backup server with a SCSI-attached DLT tape library. Additionally, each building contains a media lab that houses 15 Sun Microsystems Solaris workstations. In the basement of one of the campus buildings, an additional data center houses two application servers, a database server and two Web servers. The two campus buildings are wired to the remote building via frame relay. Media projects are handled in a workflow fashion, with data moving from department to department among the three buildings.

Five vendors responded to MediaMasters' RFP: ADIC, Amdahl Corp., Compaq Computer Corp., Hewlett-Packard Co. and McData Corp. All but McData and Amdahl, whose proposals still meet the core SAN fabric requirements, turned in complete SAN solutions that met the needs of MediaMasters' storage requirements. We were surprised and disappointed that industry leaders EMC and Unisys said they lacked the personnel resources to participate. Of the proposals we did receive, prices ranged from around $500,000 to more than $2.8 million.

One of the hang-ups in bringing SAN solutions to market has been the certification process involved in verifying hardware compatibility. Of the participating vendors, not one offers a complete in-house-designed solution. Compaq comes the closest, with hardware such as Brocade Communications Systems SilkWorm switches that it resells and optimizes for its own needs. Other vendors, such as McData, produce their own switches but partner for providing storage. The SAN infrastructure market does have major players. In the fiber-switching market, Ancor Communications, Brocade, Gadzoox Networks, McData and Vixel Corp. are market leaders. In the Fibre Channel HBA (host bus adapter) market, Emulex Corp., JNI Corp. and QuickLogic Corp. are at the forefront.

We reviewed all the proposals for scalability, fault tolerance, performance, management, interoperability, support and price. In the end, Network Computing gave HP's proposal the bid. HP provided two separate solutions: One focused on price and performance; the other was both resilient and highly manageable, which was our primary consideration. The choice of solutions demonstrated HP's capabilities, product support and flexibility in this arena. The high-end solution turned out to be the Cadillac of SANs that would accommodate even the most stringent requirements.

The other vendors' solutions laid the foundation for MediaMasters' SAN initiative and should be given further consideration in a purchasing situation. With the most cost-effective solution, Compaq receives our Best Value award. You'll find summaries and evaluations of all five vendors' proposals on the pages that follow. In addition, you'll find diagrams of the proposed solutions online.