If the connection between a running messaging engine and its data store is lost, either due to a failure or because you stop the database for maintenance, you can ensure that the messaging engine functions correctly after the connection is restored, by configuring the server to restart automatically.
The behavior described in this topic occurs only if the messaging engine is running and has established exclusive locks on its data store.
By setting the sib.msgstore.jdbcFailoverOnDBConnectionLoss custom property on a messaging engine, you can determine the behavior of the messaging engine and its hosting server in the event that the connection to the data store is lost.Property value | Behavior when the data store connection is lost |
---|---|
true (default) |
The high availability manager
stops the messaging engine and its hosting application server when
the next core group service Is alive check
takes place (the default value is 120 seconds). If a node agent is
monitoring the server, and you have enabled automatic restart in the
monitoring policy for the server, the server restarts. The messaging
engine starts when an appropriate server is available.
Note: Messages
with a reliability level that is lower than assured persistent might
be accepted by the messaging engine during the interval between Is
alive checks, and might be lost.
|
false |
The messaging engine continues to run and accept work, and periodically attempts to regain the connection to the data store. If work continues to be submitted to the messaging engine while the data store is unavailable, the results can be unpredictable, and the messaging engine can be in an inconsistent state when the data store connection is restored. Note: If
work continues to be submitted to the messaging engine, even nonpersistent
messaging can fail because the messaging engine might need to use
the data store, for example to allocate a unique ID to a message,
or to move nonpersistent messages out of memory.
|
If you want the server to restart, ensure that Automatic restart is selected in the monitoring policy for the server.
If a server restarts automatically in this situation, CWSID0039E messages appear in the JVM logs for the server.
After a server restart, click to view the status of the messaging engine. Check that the messaging engine has been restarted and is running.
If the server is a member of a cluster, check that the cluster members are still enabled for high availability, by following the instructions in the topic Managing high availability when messaging engines fail to start.
You might want to tune your system so that the loss of the database connection is detected quickly, and the messaging engine waits for a reasonable amount of time for the data store to become available again before attempting to start on another server.
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