You can use the message migration utility to reverse migrate messaging from the default messaging provider (the service integration bus) on an application server at the current version of the product to the Version 5 embedded messaging provider on a Version 5.1 application server. Reverse migration is carried out under XA coordination.
You must reverse the migration of the messages before deleting the application server on the service integration bus.
You run the message migration utility only once for a particular queue, unless a failure occurs.
If a failure occurs during message migration, it is safe to run the message migration utility again in the same direction because messages are moved rather than copied. Whether you successfully try a failing message migration again, or delete the message, the message ordering of the remaining messages is preserved on the queue on the current version of the product.
If the reverse migration takes place after a partial migration from WebSphere® Application Server Version 5.1 to a later version, in which only some of the messages were migrated, then the message ordering is not preserved. However, if the target queue in the Version 5.1 application server is empty when the migration takes place (as it is likely to be) then the message order is retained.
Messages that are reverse-migrated appear on the queue after those that were not migrated at the first attempt.