HP 8/40 Brocade Access Gateway Administrator's Guide v6.3.0 (53-1001345-01, Ju - Page 52
Failover, Failover configurations in Access Gateway
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3 Failover Failover Access Gateway Failover ensures maximum uptime for the servers. When a port is configured as an N_Port, failover is enabled by default and is enforced during power-up. Failover allows F_Ports to automatically remap to an online N_Port if the primary N_Port goes offline. If multiple N_Ports are available for failover, failover evenly distributes the F_Ports to available N_Ports belonging to the same N_Port group. If no other N_Port is available, failover does not occur. AG provides an option to specify a secondary failover N_Port for an F_Port. This N_Port is called the preferred secondary N_Port for failover. If you specify a preferred secondary N_Port for any of the F_Ports, and if the primary mapped N_Port goes offline, the F_Ports will fail over to the preferred secondary N_Port (if it is online), then re-enable. The preferred secondary N_Port that you specify must be online; otherwise, the F_Ports will become disabled. The preferred secondary N_Port is defined per F_Port. For example, if two F_Ports are mapped to a primary N_Port 1, you can define a secondary N_Port for one of those F_Ports and not define a secondary N_Port for the other F_Port. Refer to "Adding a preferred secondary N_Port" on page 34 for more information. Failover configurations in Access Gateway The following sequence describes how a failover event occurs: • An N_Port goes offline. • All F_Ports mapped to that N_Port are disabled. • If the N_Port Failover configuration is enabled and a preferred secondary N_Port is specified for the F_Port (and that N_Port is online), the F_Port fails over to the secondary N_Port, then re-enables. If the preferred port is not set, then the F_Port fails over to any available N_port in the port group. Otherwise the F_ports will be evenly distributed among available online N_ports that are part of the same port group. Example: Failover configuration This example shows the failover behavior in a scenario where two fabric ports go offline, one after the other. Note that this example assumes that no preferred secondary N_Port is set for any of the F_Ports. • First the Edge switch F_A1 port goes offline, as shown in Figure 8 on page 33 Example 1 (left), causing the corresponding Access Gateway N_1 port to be disabled. The ports mapped to N_1 fail over; F_1 fails over to N_2 and F_2 fails over to N_3. • Next the F_A2 port goes offline, as shown in Figure 8 on page 33 Example 2 (right), causing the corresponding Access Gateway N_2 port to be disabled. The ports mapped to N_2 (F_1, F_3, and F_4) fail over to N_3 and N_4. Note that the F_Ports are evenly distributed to the remaining online N_Ports and that the F_2 port did not participate in the failover event. 32 Access Gateway Administrator's Guide 53-1001345-01