Dell Brocade 6510 Access Gateway Administrator's Guide 7.1.0 - Page 75
Upgrade and downgrade considerations for the Failover policy, Failback policy
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Failback policy 3 3. Enter the ag --failoverdisable -pg pgid command to disable failover. switch:admin> ag --failoverdisable -pg 3 Failover policy is disabled for port group 3 Upgrade and downgrade considerations for the Failover policy Consider the following when upgrading or downgrading Fabric OS versions: • Downgrading to Fabric OS v6.4.0 or earlier is supported. • Upgrading from Fabric OS v6.4.0 to v7.1.0 or downgrading from Fabric OS v7.1.0 to v6.4.0 will not change failover settings. Failback policy The Failback policy provides a means for hosts that have failed over to automatically reroute back to their intended mapped N_Ports when these N_Ports come back online. The Failback policy is an attribute of an N_Port and is enabled by default when a port is locked to the N_Port. Only the originally mapped F_Ports fail back. In the case of multiple N_Port failures, only F_Ports that were mapped to a recovered N_Port experience failback. The remaining F_Ports are not redistributed. NOTE For port mapping, the Failback policy must be enabled on an N_Port for failback to occur. For device mapping, the Failback policy has no effect. If a device is mapped to a port group, it will always fail over to an online N_Port in the port group (or secondary N_Port if configured) and will remain connected to this failover N_Port when the original N_Port comes back online. NOTE If failover and failback policy are disabled, an F_Port mapped to an N_Port will go offline when the N_Port goes offline and it will go online when the N_Port comes online. Failback policy configurations in Access Gateway The following sequence describes how a failback event occurs: • When an N_Port comes back online, with the Failback policy enabled, the F_Ports that were originally mapped to it are temporarily disabled. • The F_Port is rerouted to the primary mapped N_Port, and then re-enabled. • The host establishes a new connection with the fabric. NOTE The failback period is quite fast and rarely causes an I/O error at the application level. Failback example In Example 3, described in Figure 12 on page 56, the Access Gateway N_1 remains disabled because the corresponding F_A1 port is offline. However, N_2 comes back online. See Figure 11 on page 52 for the original failover scenario. Access Gateway Administrator's Guide 55 53-1002743-01