Dell PowerEdge M420 8/4 Gbps FC SAN Module Administrator's Guide - Page 36

3 Failback Failback Failback policy provides a means for ports that have failed over to move back to their intended external ports (N_Ports) when these ports come back online. When Failback is enabled, all internal ports (F_Ports) automatically reroute back to these primary-mapped external ports. Failback is an external port parameter and is enabled by default. Only the originally mapped internal ports fail back. In the case of multiple external port failures, only internal ports that were mapped to the recovered external port experience failback. The remaining internal ports are not redistributed among the online external ports during the failback. Failback configurations in the FC SAN Module The following sequence describes how a failback event occurs: • When an external port comes back online, with Failback enabled, the internal ports that were originally mapped to it are disabled. • The internal port is rerouted to the primary mapped external port, and then re-enabled. • The host establishes a new connection with the fabric. Example: Failback configuration In Example 3, described in Figure 6 on page 23, N_1 remains disabled because the corresponding F_A1 port is offline. However, N_2 comes back online. See Figure 5 on page 20 for the original fail over scenario. The ports F_1 and F_2 are mapped to N_1 and continue routing to N_3. Ports F_3 and F_4, which were originally mapped to N_2, are disabled and rerouted to N_2, and then enabled. 22 Dell 8/4Gbps FC SAN Module Administrator's Guide 53-1001345-01