The error RMAN-06054: media recovery requesting unknown log generally occurs when RMAN cannot find the required archive logs to complete the recovery. This typically happens during a database refresh when the target database doesn't have all the necessary logs to achieve full consistency. Instead of manually using the RECOVER UNTIL command, you can automate or configure RMAN to handle this situation more gracefully by limiting the recovery to the latest available sequence.
Here are several approaches you can take to avoid this error:
Approach 1: Use SET UNTIL to Specify the Recovery Point
If you know the sequence number that represents the point you want to recover to, you can specify it in advance with the SET UNTIL command. This allows RMAN to perform recovery up to a specific sequence without needing to stop manually.
RUN { SET UNTIL SEQUENCE <latest_available_sequence>; -- Replace with the sequence number you want to recover to RESTORE DATABASE; RECOVER DATABASE; }
Approach 2: Use RECOVER DATABASE NOREDO
The NOREDO option allows you to bypass the requirement for all redo logs by performing an incomplete recovery up to the last available backup or archived redo log.
RUN { RESTORE DATABASE; RECOVER DATABASE NOREDO; }
Note: This option performs an incomplete recovery and leaves the database in an inconsistent state as of the last available redo log. Only use this if you are certain you don't need additional redo logs for full recovery.
Approach 3: Use RECOVER DATABASE UNTIL TIME
You can recover the database until a specific timestamp that aligns with your latest backup or available redo logs. This approach is useful if you know the approximate time up to which you want to recover.
RUN { SET UNTIL TIME "TO_DATE('YYYY-MM-DD HH24:MI:SS', 'YYYY-MM-DD HH24:MI:SS')"; -- Replace with the desired timestamp RESTORE DATABASE; RECOVER DATABASE; }
Approach 4: Set MAXFAIL Parameter
The MAXFAIL parameter allows RMAN to skip over missing archive logs during the recovery. This can sometimes help RMAN proceed with recovery without failing immediately on a missing log. Note that this does not guarantee full recovery if logs are missing, but it allows RMAN to skip logs more gracefully.
RUN { SET MAXFAIL 1; -- Set the number of allowed failures RESTORE DATABASE; RECOVER DATABASE; }
Approach 5: Use RMAN SKIP Option for Archivelogs
If you know specific logs are missing and do not need them, you can skip specific archived redo logs. For example:
RUN { RESTORE DATABASE; RECOVER DATABASE SKIP SEQUENCE <missing_sequence_number>; }
Note: Use this with caution as it can leave the database in an incomplete state if critical logs are skipped.
Additional Tips
Check Backup Strategy: Ensure you have a consistent backup strategy that includes all necessary archive logs for recovery. If using incremental backups, confirm that they are applied properly.
Automate Sequence Tracking: Before starting the refresh, you could query the highest available sequence number from the source and set it in your recovery script as a target sequence.
SELECT MAX(SEQUENCE#) FROM V$ARCHIVED_LOG WHERE THREAD# = 1;
Use a Shell Script Wrapper: To make your recovery more flexible, you could script the process in a shell or batch script that dynamically sets the RECOVER UNTIL SEQUENCE based on the latest available sequence. This way, the recovery can complete without manual intervention.
Example: Full RMAN Recovery Script with SET UNTIL SEQUENCE
Here is an example of a complete RMAN script using the SET UNTIL SEQUENCE command:
RUN { ALLOCATE CHANNEL c1 DEVICE TYPE DISK; SET UNTIL SEQUENCE <latest_available_sequence>; -- Replace with the highest sequence you have available RESTORE DATABASE; RECOVER DATABASE; ALTER DATABASE OPEN RESETLOGS; }
Replace <latest_available_sequence> with the highest sequence number available from your archived redo logs. This will allow the refresh to complete in one go without manual intervention.
By using the SET UNTIL, RECOVER NOREDO, or MAXFAIL options in RMAN, you can streamline the recovery process to avoid interruptions caused by missing archive logs. These methods help automate the refresh process and complete recovery in a single session.
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