When you configure the session recovery strategy to resume from the last checkpoint, the Integration Service stores the session state of operation in the shared location, $PMStorageDir. The Integration Service also saves relational target recovery information in target database tables. When the Integration Service performs recovery, it restores the state of operation to recover the session from the point of interruption. It uses the target recovery data to determine how to recover the target tables.
You can configure the session to save the session state of operation even if you do not save the workflow state of operation. You can recover the session, or you can recover the workflow from the session.