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Will IP-Based Storage Networks Take a Bite Out of Fibre Channel?

When we look at the future of Fibre Channel technology in the storage arena, it seems as though it couldn't be brighter. The installed base of Fibre Channel, which serves as the networking technology for Storage Area Networks (SANs), has been growing at a compound annual growth rate (CAGR) of 85 percent. The market-research company International Data Corporation (IDC) forecasts that the SAN market will grow from $2 billion in 2001 to $16 billion in 2004. At the same time, the Fibre Channel segment of the market will grow from $1 billion in 2000 to $4.83 billion in 2003. According to IDC, from 2001 through 2003, overall storage capacity will grow 75 percent annually, and by 2004, 67 percent of all storage will be networked.

In addition, Fibre Channel has a clear upgrade path. This summer, industry leaders (e.g., Brocade, Gadzooks) rolled out Fibre Channel switches and routers that operate at twice the speed of the previous generation but cost less than twice the price. The 2Gbps switches increase SANs' performance in data-intensive applications. Many industry observers, such as Gartner analyst James Ofer, believe that the transition to 2Gbps switches will be complete by 2002, and the move to 10Gbps will begin in 2003.

But just as Fibre Channel seemed to be hitting its stride, IP-based storage-network technology clearly emerged. This fall, proponents of the IP-based storage-protocol Internet SCSI (iSCSI) demonstrated a coast-to-coast, IP-based storage network that operated at 2.5Gbps on a 10Gbps linkā€”an accomplishment that industry analysts (such as Dan Tanner of the Aberdeen Group) described as a seminal event. Later, on October 23, iSCSI leaders showed off the interoperability of their products at the Storage Networking Industry Association (SNIA) IP Storage Forum.

IP storage is a cluster of technologies that lets users transmit block-level storage data over an IP-based network. Both aspects of IP storage are significant. Applications that rely on low-latency data access (e.g., transactional databases) require direct block-level access to the physical hardware. IP-based storage networks provide direct block-level access; traditional methods of transferring data over IP networks don't. At the same time, IP-based storage networks let companies use IP-enabled technology (e.g., Ethernet) as the basis of their SANs, and iSCSI facilitates the transmission of block-level SCSI data over a TCP/IP network.

The vision of one network technology for both SANs and LANs is compelling to some. According to the Strategic Research Group, users currently back up 89 percent of all servers over the network, with a large percentage being Ethernet subnets. Convergence could reduce both costs and complexity for network administrators.

Will moving to IP-based storage networks simply require dropping in a few IP-enabled NICs? Michael Peterson of the Strategic Research Group doesn't think so, arguing that moving storage is more complicated than many people realize. In fact, analysts and vendors sharply disagree about how competitive iSCSI will be with Fibre Channel. Jai Menon of the IBM Alamden Research Center believes that iSCSI will perform just as well as Fibre Channel and provide better quality of service and security. Others argue, however, that because of the TCP/IP overhead, iSCSI will be less efficient than Fibre Channel (in terms of throughput per second), although it will still compare favorably on criteria such as cost, complexity, and stability.

Several IP-based storage technologies are competing with iSCSI, however, including Fibre Channel over IP (FCIP), which lets users connect Fibre Channel islands over an IP-based network to form one unified SAN fabric, and Internet Fibre Channel Protocol (iFCP), which encapsulates Fibre Channel frames for sending over the IP infrastructure. Although the FCIP protocol establishes point-to-point connections to join two Fibre Channel SANs together, iFCP is a gateway-to-gateway protocol. Just because all these technologies are based on IP technology doesn't mean that they will interoperate seamlessly.

For their part, Fibre Channel adherents believe they have the power of incumbency on their side. Even officials at IBM, a company that is one of the leading advocates of iSCSI technology, concede that Fibre Channel will offer more complete solutions for the next several years.

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