About configuring NetBackup for Oracle block-level incremental backups on UNIX
If only a small portion of a database changes on a daily basis, full database backups are costly in terms of time and media. The Block-Level Incremental (BLI) Backup interface extends the capabilities of NetBackup to back up only the file system blocks that contain changed data blocks.
A database BLI backup is done at the file system block level, which means only changed file blocks are backed up. Unchanged blocks within the files are not backed up. The VxFS Storage Checkpoint facility tracks changed blocks in real time. Accordingly, a BLI backup does not need to search the entire volume for the modified blocks at backup time. BLI backup saves time, decreases the amount of backup media that is required, and significantly reduces CPU and network overhead during backups. In addition, BLI backup allows more frequent backups, so backup images are more up to date.
BLI backup is particularly useful for any large databases that are sized in terms of hundreds of gigabytes or terabytes. Most traditional methods for database backup require that any change in the database - no matter how small - requires that the entire database is backed up. With BLI backup, only modified blocks (or file) need to be backed up.
The recommended method for performing BLI backups is the proxy BLI agent with RMAN. This method supports the other features of NetBackup for Oracle, including the policy types and schedules and the convenience of the template generation wizard. It also remains tightly integrated with RMAN and its catalog, which greatly simplifies administration tasks.
You can also perform backups with the script-based BLI method without RMAN.
Note:
Veritas recommends that Snapshot Client users who want to perform BLI backups use BLI with RMAN.
NetBackup for Oracle also provides a method for BLI backup without RMAN that uses scripts to put tablespaces into, and take them out of, backup mode. This method is not recommended, and it requires a significantly different configuration. But for Oracle 12c, using script-based BLI backups without the use of RMAN are not supported.