Cross-Checking Backups

Cross-checking a backup synchronizes the physical reality of backups with their logical records in the Oracle Recovery Manager (RMAN) repository. For example, if a backup on disk was deleted with an operating system command, then a cross-check detects this condition. After the cross-check, the RMAN repository correctly reflects the state of the backups.

Backups to disk are listed as available if they are still on disk in the location listed in the RMAN repository, and if they have no corruption in the file header. Backups on tape are listed as available if they are still on tape. The file headers on tape are not checked for corruption. Backups that are missing or corrupt are listed as expired.

To cross-check individual files:

Connect RMAN to the target database as described in "Connecting to the Target Database Using RMAN."
Display a summary of the existing backups to determine which backup you want to cross-check.
```
LIST BACKUP SUMMARY;
```
Identify the backup that you want to cross-check from the output of the previous LIST command.

Cross-check the identified file using the CROSSCHECK command.

To cross-check the backup set 1345:

CROSSCHECK BACKUPSET 1345;

using channel ORA_DISK_1
crosschecked backup piece: found to be 'AVAILABLE'
backup piece handle=/ade/b/191802369/oracle/work/orcva/RDBMS/backupset/2012_04_05/o1_mf_annnn_TAG20120405T075520_7qvdlrsl_.bkp RECID=1345 STAMP=779788520
Crosschecked 1 objects

To cross-check the data files 1 and 5:
```
CROSSCHECK DATAFILECOPY 1,5;
```

To cross-check all files:

Connect RMAN to the target database as described in "Connecting to the Target Database Using RMAN."
To crosscheck all backup sets, use the following command:
```
CROSSCHECK BACKUP;
```

Note:

Cross-checking all backups in the RMAN repository may take a long time, especially for tape backups. A cross-check of all files, unlike cross-checking individual files, is handled as a scheduled job.