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