Block media recovery is a powerful and very practical RMAN feature. This feature allows the DBA to recover from the dreaded ORA-01578 ORACLE data block corrupted (file # <fileNo>, block # <blockNo>) error. In order for RMAN to be successful in recovering from this error, some conditions must be met:
The database must be in archivelog mode.
You must have a full database backup. A level 1 incremental backup is not supported in this scenario because in a missing archivelog scenario the recovery process would fail.
If flashback is enabled, RMAN can look for valid block copies, making the recovery process faster.
In the following example, some blocks were corrupted at datafile 5. The corruptions were created using the Unix command dd. When querying the database looking for data using a regular SELECT SQL command, the ORA-01578 error shows up:
SQL> select * from employees;
select * from employees
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file...