Export will read all the data and report errors at the block level and data level without obtaining any locks. However, it will not perform index/block cross checking. Only analyze table validate structure with the cascade option will do that. The best combination to detect problems would be to (analyze with validate structure cascade) and then use export.
Once In a month I just want to cross check my DB for Block corruption .
1.The physical backups is done by RMAN ...
So will v$backup_corruption will be just enough
or if need to cross check with export what is the best method ..