Enabling And Disabling The Failover Policy For A Port Group; Failback Policy; Failback Policy Configurations In Access Gateway; Failback Example - Broadcom Brocade Fabric OS 6505 User Manual

FOS-821-access-AG104 User Guide

Enabling and Disabling the Failover Policy for a Port Group

The Failover policy can be enabled on a port group. Use the following steps to enable or disable the failover on all the
N_Ports belonging to the same port group.
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the ag --failoverenable -pg <pgid> command to enable failover.
switch:admin> ag --failoverenable -pg 3
Failover policy is enabled for port group 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

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 come 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 reenabled.
•
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 the following figure, the Access Gateway N_1 remains disabled because the corresponding F_A1 port is offline.
However, N_2 comes back online. See
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.
Failover Example for the original failover scenario.
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Brocade Fabric OS Access Gateway User Guide, 8.2.x
FOS-821-access-AG104
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