Resolution:
For IM, access to the database datamanager is very critical. IM requires a connection to the database at all times, for operations like...

-checkpointing a job
-reading a checkpointed job
-getting a unique id for every message that comes into IM
-flow control
-storing global variables.

If IM looses connection to the db datamanager, IM will SHUTDOWN automatically. Here is the sequence of steps that IM follows when IM looses connection to the database..

-IM uses existing connection (from the pool) to do the datamanager operation, but will fail because it is a bad connection
-IM then tests the connection and will attempt to create a new connection. This too will fail.
-IM then shuts down

There is at least one retry attempt before IM shuts down.

There is no inbuilt support within IM for using a fault tolerant database. But certain databases like oracle can be configured as 'Data Guard' with Primary and Standby Database. So if the primary fails, the standby database becomes active. The JDBC URL connection in the IM Properties.cfg file would need to be modified to take into consideration the primary and secondary databases.

To get more information about Oracle data guard technology and architecture, refer to the following link...
http://otn.oracle.com/deploy/availability/htdocs/odg_overview.html

What happens if IM looses connection to the database datamanager ? Can IM be configured for database fault tolerance ?[Keywords : data guard]