What is Fibre Channel SAN?

Fibre Channel is a network communication protocol designed for high rates of data transfer amongst storage devices, computers, and peripherals. Used primarily as the infrastructure for storage area networks (SAN), it supports data transfer rates from 1 through 10 Gbps, and provides support for multiple topologies and protocols. Approved as an ANSI standard in 1994, the Fibre channel protocol is known for its ability to provide high-performance storage consolidation and facilitate centralized management of server and storage assets. Combined with switches, hubs, storage devices, adapters, and management software, the Fibre Channel delivers capabilities for storage networking, cluster computing and network interconnections.

Although performance is comparable, complexity, cost, and even operating distance are often the deciding factors when choosing between Fibre Channel and iSCSI, an IP-based standard for connecting data storage devices. While Fibre Channel, which uses optical fiber or twisted pair copper cabling to carry SAN data, has a theoretical operating distance of 10KM, iSCSI can be run over longer distances using existing network infrastructure. The total cost of ownership for a Fibre Channel SAN is also known to be much higher than iSCSI.

Fibre Channel networks can be implemented using three kinds of topologies: point-to-point (FC-P2P), switched fabric (FC-SW), and arbitrated loop (FC-AL). In FC-P2P, the simplest of the three topologies, two devices are connected directly to each other. FC-AL involves devices gaining control of the network loop and establishing a point-to-point connection with the receiving device – only one pair of ports can communicate concurrently on a loop. Conversely, Fibre Channel Switches manage all traffic between devices in the FC-SW topology, allowing for better failover and multiple pairs of ports to communicate simultaneously.

Fibre Channel over Ethernet (FCoE), which was approved in June 2009, is a relatively newer protocol that essentially allows Fibre Channel traffic to run over a 10Gbit/sec Ethernet network. Given the prevalence of Ethernet for TCP/IP networks and Fibre channel for SANs, FCoE provides an easy way to consolidate network traffic, reduce the number of cables and switches, and help reduce power and cooling costs (by facilitating more I/O connections with virtual servers).

Despite its relatively higher costs, few organizations are moving entirely away from their existing Fibre Channel investments. The increasing data loads being put on network infrastructures by multicore and virtual systems ensure the continued dependence on Fibre Channel technology for some time yet.