This section describes each mode in detail.
In this mode, Adaptive Server acts as a standalone server. A newly installed Adaptive Server is in single-server mode by default.
When both companions are running and are configured for fail over, they operate in normal companion mode. This is the mode in which the day-to-day operations of Adaptive Server occur. In asymmetrical systems, the primary companion can fail over to the secondary companion. In symmetric systems, either companion can fail over to the remaining companion.
In suspended mode, both servers act as single servers. Suspended mode is useful for performing system maintenance because you can start and stop the Adaptive Server and associated resources without risking failover.
The companions cannot fail over, but the nodes upon which they are working can; you must perform some platform-specific steps to suspend node fail over. Also, before you shut down a companion in suspended mode, you must perform some platform-specific tasks. See the appropriate platform-specific chapter for more information.
Many utilities and commands are severely restricted in suspended mode. See Appendix C, “Changes to Commands, System Procedures, and Databases,” for more information.
You should suspend a companion mode only from the secondary companion.
Adaptive Server must enter a failback mode to move from failover mode on the secondary companion to normal companion mode on the primary companion.
Failback is a planned event. That is, it is only done when the System Administrator determines that the system is ready to resume normal operations. Use sp_companion prepare_failback to initiate fail back and migrate the failed-over Adaptive Server to its original node. See “Performing failback”.
To resume normal companion mode, enter:
sp_companion "primary_server_name", resume
To permanently disable companion mode, enter:
sp_companion “server_name”, 'drop’
When this command is complete, the two Adaptive Servers are no longer companion servers and are running in single-server mode.
drop is an irreversible operation.
Once you have reverted the companion servers to single-server mode,
you must dump, drop, and reload all user databases to reconfigure
them as companions.
If the companion you drop is in a symmetric setup, the cluster automatically assumes an asymmetric setup between the companions.
