Failover And Failback Policies; Cold Failover; Port Initialization - Brocade Communications Systems A7533A - Brocade 4Gb SAN Switch Base Administrator's Manual

1

Failover and Failback policies

Failover and Failback policies

When a port is configured as an N_Port, the Failover policy is enabled by default. If a primary
N_Port goes offline because a cable is removed or any other offline event, the F_Ports that are
mapped to the N_Port are disabled. If a Preferred Secondary N_Port is set for any of the F_Ports,
and if those N_Ports are online, these F_Ports will be failed over to their respective Preferred
Secondary N_Port, and then re-enabled. Otherwise, if a Preferred Secondary N_Port is set, but is
not online, those F_Ports are disabled.
Alternatively, if a Preferred Secondary N_Port is not set for any of these F_Ports, these F_Ports
fail-over to other online N_Ports belonging to the same N_Port group, and then re-enables. The
FLOGI and FDISC requests are forwarded from F_Ports through the new N_Port. Failover of F_Ports
to new N_Ports generates a RASLOG message. If multiple N_Ports are available as candidates for
failover, Access Gateway selects one or more N_Ports so that the F_Ports are evenly balanced
across all these N_Ports.

Cold Failover

All F_Ports for an N_Port that goes offline are failed over to other N_Ports. However, if the N_Port
fails to come online after the switch comes online, it triggers cold failover of its F_Ports. If any of
these F_Ports have the Preferred Secondary N_Port set, and if the Preferred Secondary N_Port is
online, those F_Ports fail over to the Preferred Secondary N_Port during cold failover. If a Preferred
Secondary N_Port is set for any of these F_Ports and the Preferred N-Port is not online, then those
F_Ports are disabled. If the Preferred Secondary N_Port is not set for any of these F_Ports, these
F_Ports failover to any N_Ports on the switch so that the F_Ports are evenly balanced across all the
N_Ports belonging to the same N_Port group.
NOTE
Access Gateway incorporates a number of Path Failover and Failback policies to ensure maximum
up time for the servers.

Port initialization

To ensure that all hosts are brought online when Brocade Access Gateway starts up, the ports are
initialized in the following manner:
1. All N_Ports are initialized. During N_Port initialization all the F_Ports are disabled (kept offline).
2. All F_Ports mapped to online N_Ports are enabled.
3. F_Ports mapped to an offline N_Port with the failover policy enabled fail over to an online
4. The host logs in to the fabric as follows:
6
The ports are enabled or disabled as follows:
•
Enabled (online) if the port receives a fabric login event and is connected to an F_Port of
an edge switch that supports NPIV (N_Port ID virtualization).
•
Disabled (offline) if the port is not connected to a fabric or is connected to a fabric port
that does not support NPIV.
N_Port.
Access Gateway Administrator's Guide
53-1000605-01