Tales From A Lazy Fat DBA

NOFILENAMECHECK (RMAN Parameter) is used to handle Data Block’s corruptions during Backup’s.

By default a checksum is calculated for every block read from a datafile and stored in the backup or image copy. If you use the NOCHECKSUM option, then checksums are not calculated. If the block already contains a checksum, however, then the checksum is validated and stored in the backup. If the validation fails, then the block is marked corrupt in the backup.

By default, the BACKUP command computes a checksum for each block and stores it in the backup. The BACKUP command ignores the values of DB_BLOCK_CHECKSUM because this initialization parameter applies to data files in the database, not backups. If you specify the NOCHECKSUM option, then RMAN does not perform a checksum of the blocks when writing the backup.

You cannot disable checksums for data files in the SYSTEM tablespace even if DB_BLOCK_CHECKSUM=false.

“To speed up the process of copying, you can use the NOCHECKSUM parameter. By default, RMAN computes a checksum for each block backed up, and stores it with the backup. When the backup is restored, the checksum is verified.”