How do you troubleshoot common RMAN errors and failures?

1 Check the RMAN log

The first step to troubleshoot any RMAN issue is to check the RMAN log file, which records the commands, messages, and results of each RMAN session. You can find the RMAN log file in the directory specified by the LOG parameter of the RMAN command, or in the default location of $ORACLE_HOME/rdbms/log. The RMAN log file contains useful information such as the RMAN version, the database name, the backup location, the error codes, and the recovery steps. You can use the RMAN log file to identify the cause and the scope of the problem, and to follow the recommended actions to resolve it.

2 Use the V$ views

Another useful source of information for troubleshooting RMAN issues is the set of dynamic performance views that start with V$, such as V$BACKUP_PIECE, V$ARCHIVED_LOG, V$DATABASE_BLOCK_CORRUPTION, and V$RMAN_STATUS. These views provide details about the status, progress, and outcome of RMAN operations, such as backup, restore, recover, validate, and delete. You can query these views to monitor and verify the RMAN activities, and to detect any anomalies or errors. For example, you can use the V$DATABASE_BLOCK_CORRUPTION view to find out which data blocks are corrupted and need to be repaired.

3 Use the VALIDATE command

One of the most useful commands for troubleshooting RMAN issues is the VALIDATE command, which checks the integrity and availability of backup sets, backup pieces, archivelogs, datafiles, control files, and spfiles. The VALIDATE command does not perform any actual restore or recovery, but it simulates the process and reports any errors or warnings. You can use the VALIDATE command to test the validity of your backups before you need them, to identify any missing or expired files, to detect any corrupted blocks, and to estimate the time and space required for recovery.

4 Use the DEBUG option

If you need more detailed information about the RMAN operations and errors, you can use the DEBUG option of the RMAN command, which enables the tracing and logging of RMAN internal events. The DEBUG option allows you to specify the level of detail and the type of events you want to trace, such as error, info, sql, or protocol. You can also specify the output destination of the debug messages, such as a file or a screen. The DEBUG option can help you to understand how RMAN works, what commands it executes, what messages it sends and receives, and what errors it encounters.

5 Use the CROSSCHECK command

Sometimes, the RMAN catalog or control file may have outdated or incorrect information about the backup sets, backup pieces, or archivelogs, which can cause errors or failures when you try to use them. For example, you may have deleted or moved some files manually, or some files may have been damaged or corrupted. To avoid these problems, you can use the CROSSCHECK command, which compares the information in the RMAN catalog or control file with the actual files on disk or tape. The CROSSCHECK command updates the status of the files to reflect their current availability, and marks any missing or inaccessible files as expired or obsolete.

6 Use the REPORT command

Finally, one of the most helpful commands for troubleshooting RMAN issues is the REPORT command, which generates various reports about the backup and recovery status of your database. The REPORT command can tell you what backups are needed, what backups are obsolete, what backups are recoverable, what backups are missing, and what backups are corrupted. You can use the REPORT command to plan your backup and recovery strategy, to optimize your backup space usage, to ensure your backup consistency, and to identify any potential issues that may affect your recovery.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?