Failback policy, Failback policy configurations in access gateway, Failback example – Dell POWEREDGE M1000E User Manual
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Access Gateway Administrator’s Guide
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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
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
on page 52 for the original failover scenario.