Failover Configurations - Dell PowerEdge M420 Administrator's Manual

Failover configurations

The following sequence describes how a failover event occurs:
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Example: Failover configuration
The example in
scenario where two fabric ports go offline, one after the other. Note that this example assumes that
no preferred secondary external port (N_Port) is set for any of the internal ports (F_Ports).
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Dell 8/4Gbps FC SAN Module Administrator's Guide
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An external port (N_Port) goes offline.
All internal ports (F_Ports) mapped to that external port are disabled.
If the external port Failover configuration is enabled and a preferred secondary port is
specified for the internal port (and that external port is online), the internal port fails over to the
secondary external port, then re-enables. If the preferred port is not set, then the internal port
fails over to any available external port in the port group. Otherwise the internal ports will be
evenly distributed among available online external ports that are part of the same port group.
"Example 1 and 2 Failover behavior"
First the Edge switch F_A1 port goes offline, as shown in
causing the corresponding N_1 port to be disabled.
The ports mapped to N_1 fail over; F_1 fails over to N_2 and F_2 fails over to N_3.
Next the F_A2 port goes offline, as shown in
the corresponding N_2 port to be disabled.
The ports mapped to N_2 (F_1, F_3, and F_4) fail over to N_3 and N_4. Note that the internal
ports are evenly distributed to the remaining online external ports and that the F_2 port did not
participate in the failover event.
on page 20 shows the failover behavior in a
Figure 5 on page 20 Example 1 (left),
Figure 5 on page 20 Example 2 (right), causing
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Failover
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