Backup Verifications (SAP Library - Database Administration (Oracle) with SAPDBA)

Backup Verifications

Database verifications must be checked regularly for readability and completeness. This avoids errors occurring when reading from the volume even though the backup was made successfully.

Verification Strategy

At least once in every backup cycle (tape administration cycle) you should check the contents of a complete database backup. A check on the Oracle internal block structure should also take place once in every cycle. Both checks complement each other. However they do not replace each other, since they check different aspects.

Verification of Backups with BRBACKUP -w| -verify

The method and extent of a BRBACKUP check differs according to the type of backup:

Offline backup: After the backup the files are copied back to a temporary directory ( compress_dir ) and compared to the originals one-by-one.

Online backup: After the backup the files are copied back to a temporary directory ( compress_dir ) but only the file sizes are compared.

Verification is always carried out between volumes: the volumes are written to one after the other, and then the backup is verified.

See -w|-verify

Independent Verification of Backups with BRRESTORE -w| -verify

You can carry out the backup and the readability check on the backed up files independently from each other. The backup check can then be delayed to a later point in time. You can even execute the verification process on another computer.

When checking a backup with BRRESTORE ( brrestore -verify ) only the readability of the tape or disk backups is checked, not the contents. The files are only read, not restored.

See -w|-verify

Verification of Backups with BRARCHIVE -w| -verify

The extent of the check on archived offline redo log files depends on the type of BRARCHIVE backup:

brarchive -s|-sc|-ss|-cs : The backed up files are restored and compared with the originals one-by-one.

brarchive -sd|-scd|-ssd|-cds : The file sizes of the archived offline redo log files are checked. Since the originals were deleted, a check on the contents is not possible.

See -w|-verify

Verification of Backups with Oracle DB_VERIFY

From ORACLE Release 7.3 the tool DB_VERIFY from Oracle is available, in order to check the Oracle internal block structure of backups or check the database files directly. This means you can recognize errors early (ORA-1578), before they lead to the termination of a program in an application that accesses the blocks. (There is no one-to-one comparison).

DB_VERIFY has the following options:

Database backup with subsequent restoration to a temporary directory ( compress_dir ) and check on the Oracle block structure:

brbackup -w use_dbv

Online block structure check on the database files without backup:

brbackup -w only_dbv

Any number of these verification processes can run in parallel (parameter: exec_parallel , option -e ).

Temporary restoration of a database backup ( compress_dir ) and verification of the Oracle block structure:

brrestore -w use_dbv.

The restoration implicitly checks the readability of the backup.