Automatic Rollback recovery is the first line of defense in protecting the integrity of an IMS database. It is the most expeditious method of restoring a database, thus minimizing the time that a particular database must be offline. Automatic Rollback recovery is disabled by default. When enabled, Enterprise Server invokes it automatically to check for and repair corrupted data when an IMS transaction or the IMS Database Engine fails, backing out uncommitted data for all databases specified in the unit of work, thereby restoring the database.
In addition, you can manually invoke Rollback recovery as a JCL job, or using the mfims imsdbu Rollback function from the command line. These options provide you with a means to control the time and circumstances under which a Rollback recovery is performed.