Although the biggest benefit from the 2G bit version of Fibre Channel for SANs is the increased speed, the new standard (Fibre Channel Switch Fabric 2, or FC-SW-2) also conserves ports on SAN switches and allows switches to pack more ports into the same space.
Because of the higher speed, a single backbone link between switches or SAN islands can do the work of two 1G bit links. This reduces the number of ports needed to support the same throughput and also eliminates the synchronization issues that can arise when two links are used as a backbone.
Although it is not part of the standard, most 2G bit switches support a new kind of connector called the SFP (Small Form-factor Pluggable) for Fibre Channel. Like the common Gigabit Interface Converter connector, the SFP allows the use of optical fiber or copper cable by accommodating the appropriate connector and interface circuits. However SFP is slightly less than half the width of the earlier design -- 0.65 inch versus 1.25 inch for the older design -- which means that switches and other equipment can accommodate twice as many ports in the same rack space. And in addition to many other benefits, the new standard allows for exchanging zoning information. This means that administrators could restrict the view of storage devices on a SAN; some could see only Windows servers, for example, while others would see only Solaris systems, which could allow easier management.
Gadzoox Networks has a white paper on 2G bit Fibre Channel titled "Third Generation SANs Open 2GB Fabric" on its Web site at www.gadzoox.com.
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
