Changing active status from one server to another is called switchover. The server on which the LSMS is running at a given time is called the active server. If the other server is in STANDBY state, it is called the standby server. (If the other server is in UNINITIALIZED "INHIBITED" state, the LSMS is said to be running in simplex mode, which means that only one server is currently available to run the LSMS application, and switchover is not possible.) During switchover, the server that was in ACTIVE state changes to UNINITIALIZED "INHIBITED" state and the server that was in STANDBY state changes to ACTIVE state.
What Happens During Switchover?
During a switchover, the following functions occur:
- The active server shuts down the LSMS application and transitions to UNINITIALIZED "INHIBITED" state.
- The standby server stops replicating the MySQL database.
- The standby server starts the LSMS application.
Note: After switchover the state of the previously active server is
UNINITIALIZED "
INHIBITED", so this server is not ready to act as a standby server. As soon as possible, perform the procedure described in
“Starting a Server” to put this server in
STANDBY state.
The following items describe the results of a switchover:
- All NPAC associations are terminated and then automatically restarted to connect to the newly active server (for more information, see LSMS Connectivity)
- All EMS associations are terminated and then automatically restarted to connect to the newly active server (for more information, see LSMS Connectivity)
- The Virtual IP (VIP) address is switched from the previously active server to the newly active server. In all types of network configuration, the VIP address is used for the application network, which is used by the following functions:
- The Service Assurance feature is restarted by the Surveillance feature after the newly active server takes over.
- After directly-connected Query Servers detect a period of inactivity, they attempt to reconnect. The reconnection is made to the newly active server.
- Web-based GUIs (if this feature is enabled).
Note: Although it is possible to start a web-based GUI by specifying the server’s specific IP address, it is recommended that web-based GUIs use the VIP address. Any web-based GUIs that do not use the VIP address will terminate during switchover.
Switchover has the following effects on connections on the web-based GUIs that use the VIP address:
- An alarm that switchover is being initiated is displayed
- Any user-initiated actions, such as audits or bulk loads, are terminated
- All web-based GUI sessions automatically reconnect themselves to the newly active server within the GUI refresh interval
- Until the GUI reconnects, no new GUI notifications will be displayed
For some types of failure on the active server, the LSMS automatically attempts to switch over. If automatic switchover is not possible, or at any time you wish, you can manually switch over to the other server. For more information about switching over, see the following:
What Needs to Happen When Switchover Completes?
When automatic or manual switchover completes, the LSMS is operating in simplex mode, with one server in ACTIVE state and the other server in UNINITIALIZED "INHIBITED" state. Only the server in ACTIVE state is in a condition that is available for running the LSMS application.
As soon as possible, manual intervention is needed to change the state of the non-active server to STANDBY state by performing the procedure described in Starting a Server. When this procedure is performed on a non-active server (while the other server is in ACTIVE state), the following functions are performed:
- The MySQL binary logs of the active server are copied to the server being started.
- The server being started takes the MySQL slave role and begins database replication.
- The server changes to STANDBY state; it is now available if switchover is needed again.