使用validate驗證資料檢查資料壞塊

You can use the VALIDATE command to manually check for physical and logical 
corruptions in database files. This command performs the same types of checks as 
BACKUP VALIDATE, but VALIDATE can check a larger selection of objects. For 
example, you can validate individual blocks with the VALIDATE DATAFILE ... 
BLOCK command.
When validating whole files, RMAN checks every block of the input files. If the 
backup validation discovers previously unmarked corrupt blocks, then RMAN 
updates the V$DATABASE_BLOCK_CORRUPTION view with rows describing the 
corruptions.
Use VALIDATE BACKUPSET when you suspect that one or more backup pieces in a 
backup set are missing or have been damaged. This command checks every block in a 
backup set to ensure that the backup can be restored. If RMAN finds block corruption, 
then it issues an error and terminates the validation. The command VALIDATE 
BACKUPSET enables you to choose which backups to check, whereas the VALIDATE 
option of the RESTORE command lets RMAN choose.