Clearly, iSCSI isn't an either-or alternative to Fibre Channel. Most storage vendors agree, calling the technologies complementary and placing iSCSI on the "edge" and FCP in the "core." To hear many tell it, iSCSI will soon provide an inexpensive means to connect outlying servers to Fibre Channel fabrics in the data center. Some even concede that iSCSI will handle the interconnection requirements of SMBs (small and midsize businesses), which rarely have high-performance transaction-processing databases or other bandwidth-intensive applications. We sometimes hear the expression "SAN for the everyman" to express this position, though it's unclear to us why the everyman needs a SAN. For more on that question, see "SMBs and SANs: Where's the Urgency?".
One thing we took away from the vendor responses: Behind the scenes, an interconnect war is being waged. Only a few years ago, a spokesperson for Cisco Systems stood onstage at a technology conference and dismissed the promised speeds and feeds of Fibre Channel as "yesterday's bandwidth tomorrow." The leading proponent of all things IP has since ratcheted back its rhetoric and, with the acquisition of Andiamo Systems in August 2002, is even selling its own line of FC switches. Cisco has shifted its approach from "technology advocacy" to "consumer advocacy"--apparently a realpolitik acknowledgment that 2 percent of companies account for nearly 65 percent of storage purchases, and that you can't sell a port of anything not Fibre Channel to Fortune 500 storage administrators.
It's telling, however, that the technologies being advanced by Cisco in the Fibre Channel market, like VSAN (Virtual SAN), are transferable to iSCSI. We wouldn't be surprised if the company's current FC play is intended to establish its bona fides in storage while funding R&D aimed at what many observers quietly regard as the future of SANs: iSCSI. Rebuffed in its efforts to have VSAN approved as a standard by the overseers of Fibre Channel standards, ANSI's T11 Committee, Cisco went instead to the Internet Engineering Task Force's IP Storage Working Group, which developed iSCSI, to solicit backdoor recognition of VSAN via a standard MIB to be used in conjunction with SNMP-based device management.
It's the Money, Honey
Unlike Fibre Channel, where per-connection prices have been slow to fall, iSCSI can be operated over existing LANs or, if configured as separate networks for security's sake, can be deployed inexpensively thanks to the dramatically falling prices of Gigabit Ethernet switches and NICs. An unmanaged GigE switch can be had for less than $30 per port, compared with FC SAN switches at $450 to $1,000 per port.