Upgrade And Downgrade Considerations For The Failover; Policy; Failback Policy; Failback Policy Configurations In Access Gateway - HP StoreFabric SN6500B Administrator's Manual

3. Enter the ag
Upgrade and downgrade considerations for the Failover policy
Consider the following when upgrading or downgrading Fabric OS versions:
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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:
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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
because the corresponding F_A1 port is offline. However, N_2 comes back online. See
on page 52 for the original failover scenario.
Access Gateway Administrator's Guide
53-1002743-01
failoverdisable -pg pgid command to disable failover.
--
switch:admin> ag --failoverdisable -pg 3
Failover policy is disabled for port group 3
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.
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.
Figure 12 on page 56, the Access Gateway N_1 remains disabled
3

Failback policy

Figure 11
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