HP StorageWorks 8/80 HP StorageWorks Fabric OS 6.2 administrator guide (5697-0 - Page 342

Domain 1 7 1 8 9 2 Domain 3 9 10 12 = Dedicated Path = Ports in the TI zone 7 6 5 4 Domain 4 Figure 42 Traffic Isolation zone creating a dedicated path through the fabric In Figure 42, all traffic entering Domain 1 from N_Ports 7 and 8 is routed through E_Port 1. Similarly, traffic entering Domain 3 from E_Port 9 is routed to E_Port 12, and traffic entering Domain 4 from E_Port 7 is routed to the devices through N_Ports 5 and 6. Traffic coming from other ports in Domain 1 would not use E_Port 1, but would use E_Port 2 instead. Use the zone command to create and manage TI zones. See the Fabric OS Command Reference for details about the zone command. TI zone failover A TI zone can have failover enabled or disabled: • Disable failover if you want to guarantee that TI zone traffic uses only the dedicated path, and that no other traffic can use the dedicated path. • Enable failover if you want traffic to have alternate routes when either the dedicated or non-dedicated paths cannot be used. IMPORTANT: If failover is disabled, use care when planning your TI zones so that non-TI zone devices are not isolated. If this feature is not used correctly, it can cause major fabric disruptions that are difficult to resolve. See "Additional considerations when disabling failover" on page 341 for additional information about using this feature. Table 75 compares the behavior of traffic when failover is enabled and disabled. Table 75 Comparison of traffic behavior when failover is enabled or disabled in TI zones Failover enabled Failover disabled If the dedicated path cannot be used, the TI zone traffic will use a non-dedicated path instead. Non-TI zone traffic will use the dedicated path if no other paths through the fabric exist, or if the non-dedicated paths are not the shortest paths. If the dedicated path cannot be used, traffic for that TI zone is halted until the dedicated path is fixed. Non-TI zone traffic will never use the dedicated path, even if there are no other paths through the fabric. For example, in Figure 42, if the dedicated ISL between Domain 1 and Domain 3 goes offline, the following occurs, depending on the failover option: • If failover is enabled for the TI zone, the traffic is routed from Domain 1 to Domain 3 through E_Ports 1,2 and 3,10. • If failover is disabled for the TI zone, the traffic is halted until the ISL between Domain 1 and Domain 3 is back online. If the non-dedicated ISL between Domain 1 and Domain 3 goes offline, the following occurs, depending on the failover option: 340 Optimizing fabric behavior