Before deploying the migration files or making any other changes to the target environment, back it up. Back up the EPIM database and migrate out the entire data model or at least the objects that will be affected by the migrate in. The database backup is only good for immediate rollback. The object backup can be applied to roll back model changes at a later time should that be determined is necessary. It is possible that some issues with a deployment are not immediately discovered, even with smoke testing and post-migration compare using the compare-extract scripts.