Enables or disables controlled handover.
where state is either TRUE, or FALSE.
This hardware command enables or disables the controlled handover feature. The TRUE option enables and the FALSE option disables the action. The list option provides a listing of the Subnet Manager settings in respect to priority, controlled handover, and subnet prefix.
Note - You must stop or disable the OpenSM Subnet Manager before using the setcontrolledhandover command. See disablesm Command.
The InfiniBand specification identifies two parameters used to negotiate a master Subnet Manager - the Subnet Manager priority and the port GUID. Should two or more Subnet Managers have the same highest configured priority, the Subnet Manager with the lowest GUID becomes the master Subnet Manager.
If an un-controlled or automatic handover state exists, when the primary-and-master Subnet Manager fails, the secondary-and-standby Subnet Manager takes on the role of the new master Subnet Manager. During this time, traffic is temporarily suspended as the secondary-and-master Subnet Manager discovers and sets up the InfiniBand fabric.
If the primary Subnet Manager is able to recover from the failure, reboot, and reinitialize itself, it identifies itself as the intended master Subnet Manager. Again, traffic is temporarily suspended as the primary-and-master Subnet Manager re-discovers and sets up the InfiniBand fabric. The secondary Subnet Manager returns to the standby status.
If controlled handover is enabled, then some priority values become reserved. The Subnet Managers dynamically adjust their respective priorities to avoid the dual handover situation. A secondary Subnet Manager that became a master Subnet Manager due to a handover raises its priority to a reserved value and retains its master Subnet Manager status. Regardless if the primary Subnet Manager comes back online, the second handover does not occur.
The user-configured priorities of the Subnet Managers are retained, only during a handover are reserved priorities used.
The result of this scheme is that the user-configured priority is respected during system boot, but dual handover does not occur because the primary Subnet Manager loses its master Subnet Manager status (secondary Subnet Manager priority changes to reserve).
Note - Manually starting Subnet Managers individually is equivalent to the system boot sequence.
The setcontrolledhandover command is available from the /SYS/Fabric_Mgmt Linux shell target of the Oracle ILOM CLI interface.
The following example shows how to enable a controlled handover of Subnet Managers with the setcontrolledhandover command.
# setcontrolledhandover TRUE Current SM setttings: smpriority 0 controlled_handover TRUE subnet_prefix 0x fe80000000000000 #