What is a SAN fabric?

A San fabric is the hardware that connects servers and workstations to storage devices in a SAN. A San is configured into a number of zones. These zones include host zones, system zones, and disk zones. The SAN fabric is made up of the devices which connect these zones together allowing an any-storage-any-device connection environment. This includes a number of Fiber Channel based Switches and Routers sometimes referred to as Domains. A SAN fabric can contain two hundred and thirty nine domains, scaling out to over fifteen million connections within a single fabric. The number of devices within a SAN fabric determine what level of SAN topology can be implemented. The more complex and resilient a SAN topology is, the larger the SAN fabric require to support it.  

Recommendations when constructing a SAN Fabric

• Ensure core switches have the highest performance
• Use edge/core/core/edge or core/edge topology as appropriate
• Use MPIO based failover where possible
• Separate storage and servers by edge switches
• Create redundancy for switches, port and paths
• Use redundant fabrics
• Keep redundant fabrics consistent regarding port locations to simplify maintenance
• Consider using ICL chassis links if your switches support them to save on ports
• Keep cable lengths as consistent as possible, moreso for ICL connections.
• Have a minimum of 2 core switches
• Have at least 2 trunks between every core - edge pair