Data Mover jobs may fail to complete successfully if they are blocked because there are locks on source or target database objects.
Data Mover provides four configuration properties that can be set to detect whether object locks exist, and to retry starting blocked jobs at a specified interval. These blocked job configuration properties can be edited in the configuration.xml file.
If blocked job detection is enabled, Data Mover must run a query for each table being copied. Therefore, there may be a noticeable decrease in performance when this feature is enabled. If you are moving an entire database, the queries are run one time on a randomly chosen table in the database to check for database locks.