8.5.10. HA-Modes auto and standby
The attribute ha_mode can be used to configure which of the two shared Ethernet adapters should be the primary (active). For HA failover, one of the two values auto or standby can be configured for each of the two SEAs. The value of ha_mode together with the trunking priority (trunk_priority) decides which SEA is primary and which SEA is backup. All possible combinations are shown in the following table:

If both SEAs have the same value for ha_mode, the trunking priority (trunk_priority) decides which SEA is primary. The SEA with the higher priority (lower value) is the primary SEA. If one SEA has the value standby and the other SEA the value auto, then the SEA with the value auto for ha_mode is the primary SEA.
A manual failover can be performed by changing the ha_mode attribute. The initial state is: both SEAs are configured with the value auto, therefore ms05-vio1 with the higher trunking priority is the primary SEA (ent43):
$ vios lssea ms05-vio1 ent43
TIMES TIMES TIMES BRIDGE
NAME HA_MODE PRIORITY STATE PRIMARY BACKUP FLIPFLOP MODE
ent43 Auto 1 PRIMARY 1 0 0 All
$
If the ha_mode of the primary SEA is changed to standby, the previous backup SEA becomes the new primary. The attribute can be changed using the “vios chdev” command:
$ vios chdev ms05-vio1 ent43 ha_mode=standby
$
The previous Primary SEA on ms05-vio1 immediately becomes the Backup SEA, the previous Backup SEA on ms05-vio2 becomes the new Primary SEA:
$ vios lssea ms05-vio1 ent43
TIMES TIMES TIMES BRIDGE
NAME HA_MODE PRIORITY STATE PRIMARY BACKUP FLIPFLOP MODE
ent43 Standby 1 BACKUP 1 1 0 None
$
$ vios lssea ms05-vio2 ent41
TIMES TIMES TIMES BRIDGE
NAME HA_MODE PRIORITY STATE PRIMARY BACKUP FLIPFLOP MODE
ent41 Auto 2 PRIMARY 1 1 0 All
$
If the SEA on ms05-vio1 is to become Primary again, the ha_mode attribute must be set to auto again:
$ vios chdev ms05-vio1 ent43 ha_mode=auto
$
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