Why and when to perform this task
When an application server instance with active transactions in progress is restarted after a failure, the transaction service uses recovery logs maintained by each transactional resource to rerun any in-doubt transactions and return the overall system to a self-consistent state. This recovery process begins as soon as all of the necessary subsystems within the application server are available. If the application server is not restarted in recovery mode, the application server can start accepting new work at the same time it is processing the recovery work.Normally, this is not a problem. However, there are situations when your operating procedures might not be compatible with allowing the application server to perform recovery work and new work simultaneously. For example, you might have a high availability environment where the work handled by the application server that failed is immediately swapped over to another application server. This backup application server then exclusively processes the work from the application server that failed until recovery has completed on the failed application server and the two application servers can be re-synched. In this situation, you might want the failing application server to only perform its transactional recovery process and then shut down. You might not want this application server to start accepting new work while the recovery process is taking place.
The only way to prevent new work from being assigned to an application server that is going through its transaction recovery process is to restart the application server in recovery mode.
When you restart a failed application server, the node agent for the node on which the failed application server resides must be running before you can restart that application server.
This procedure for starting an application server normally also applies to restarting an application server. The one exception might be if an application server fails and you want the recovery functions to complete their processing prior to new work being started on that application server. In this type of situation you should restart the application server in recovery mode.
To be able to restart an application server in recovery mode, you must perform the following steps before initially starting the application server:
Steps for this task (dependent on configuration)
Result
The application server restarts in recovery mode, performs transactional recovery, and shuts down. Any resource locks the application server held prior to the failure are released.