An FC or FCoE zone is a subset of the fabric that consists of a group of FC or FCoE ports or nodes that can communicate with each other. You must contain the nodes within the same zone to allow communication.
Reasons for zoning
- Zoning reduces or eliminates cross talk between initiator HBAs. This occurs even in small environments and is one of the best arguments for implementing zoning. The logical fabric subsets created by zoning eliminate crosstalk problems.
- Zoning reduces the number of available paths to a particular FC or FCoE port and reduces the number of paths between a host and a particular LUN that is visible. For example, some host OS multipathing solutions have a limit on the number of paths they can manage. Zoning can reduce the number of paths that an OS multipathing driver sees. If a host does not have a multipathing solution installed, you need to verify that only one path to a LUN is visible.
- Zoning increases security because there is limited access between different nodes of a SAN.
- Zoning improves SAN reliability by isolating problems that occur and helps to reduce problem resolution time by limiting the problem space.
Recommendations for zoning
- You should implement zoning anytime four or more hosts are connected to a SAN.
- Although World Wide Node Name zoning is possible with some switch vendors, World Wide Port Name zoning is recommended.
- You should limit the zone size while still maintaining manageability. Multiple zones can overlap to limit size. Ideally, a zone is defined for each host or host cluster.
- You should use single-initiator zoning to eliminate crosstalk between initiator HBAs.