Automatic Repair of Corrupt Data Blocks on Standby Database

If a corrupt data block is encountered when a primary database is accessed, it is automatically replaced with an uncorrupted copy of that block from a physical standby database. This requires the following conditions:

• The physical standby database must be operating in real-time query mode, which requires an Active Data Guard license.
• The physical standby database must be running real-time apply.

Also keep the following in mind:

• Automatic repair is supported with any Data Guard protection mode. However, the effectiveness of repairing a corrupt block at the primary using the noncorrupt version of the block from the standby depends on how closely the standby apply is synchronized with the redo generated by the primary.
• When an automatic block repair has been performed, a message is written to the database alert log.
• If automatic block repair is not possible, an ORA-1578 error is returned.

If a corrupt data block is discovered on a physical standby database, the server attempts to automatically repair the corruption by obtaining a copy of the block from the primary database if the following database initialization parameters are configured on the standby database:

• The LOG_ARCHIVE_CONFIG parameter is configured with a DG_CONFIG list and a LOG_ARCHIVE_DEST_n parameter is configured for the primary database.
  or
• The FAL_SERVER parameter is configured and its value contains an Oracle Net service name for the primary database.