Rman command crosscheck

Purpose of a crosscheck command
 
If the backup is damaged or does not exist on the disk and the backup set is still recorded in the rman database or the archive is available, you need to run crosscheck to perform cross-validation to update outdated information in the rman database.

2. Prerequisites

1. When executing this command, the database must be started to the mount state.
2 crosscheck verifies all specified backups and copies, even if the backups and copies are created in the previous incarnations.
3. If Automatic channels are not configured for the database, run allocate channel for maintenace before performing crosscheck.
 
3. Precautions for this command
1 The crosscheck command only verifies the files currently recorded in the rman database. In fact, it verifies that the backup records in the database are consistent with the actual existence of the backup.
2 The crosscheck command does not delete operating system files or remove related records from the database. delete expired must be used to delete all expired backups.

4. Differences between expired and obsolete statuses in RMAN

1 expired
When running the crosscheck command, rman will verify whether each backup record in its database exists physically. If it does not exist, rman updates the backup status from available to expired, in essence, this backup cannot be reused.
2 obsolete
When the backup set exceeds the backup retention policy, the backup set is marked as obsolete, but the status of the Backup set is not available, and it is still available when it is restored.

Five related statements

Crosscheck backup;
Crosscheck copy of database;
Corsscheck backupset 114;
Crosscheck backuppiece tag 'xxxxxx ';
Crosscheck backup of archivelog all;
Crosscheck backup of database completed after 'sysdate-1 ';

Oracle related: Rman crosscheck Delete invalid Archive

Detailed description of the cross check command under RMAN

Basic Oracle tutorial-copying a database through RMAN

Reference for RMAN backup policy formulation