Your analysis of the situation regarding v$nonlogged_block is correct. The reason NONLOGGED_START_TIME is null and your SCN_TO_TIMESTAMP conversion is failing is that the NOLOGGING operations that affected these blocks occurred further in the past than the database's SCN-to-timestamp mapping retention period allows. Oracle maintains this mapping for a limited time, so any SCN older than this cannot be resolved to a specific timestamp. It is crucial to understand that these blocks are not "corrupt" on the primary database; they contain valid data. However, they represent a potential recovery issue because the changes were not captured in the redo logs, which would cause them to appear as genuinely corrupt blocks on a physical standby database or if you needed to perform media recovery over that time period. The next step is to join v$nonlogged_block with dba_extents to identify the specific objects (tables or indexes) affected, which will allow us to take corrective action, such as rebuilding an index or reloading a table, to ensure full recoverability and clear these entries.

Thanks Rahul and Somashekar for quick reply and guidiance…..🙂

Thanks Everybody for sharing these replies, I really appreciate them! I will check and see how they work and come back here with the feedback.

Regards,

Charles