NetBackup for Oracle terms
The table describes the important terms that might be new to an Oracle database administrator or a NetBackup administrator.
Term | Definition |
|---|---|
Full backup | A full backup backs up all the blocks into the backup set, skipping only data file blocks that have never been used. Note that a full backup is not the same as a whole database backup; "full" is an indicator that the backup is not incremental. A full backup has no effect on subsequent incremental backups, which is why it is not considered part of the incremental strategy. In other words, a full backup does not affect which blocks are included in subsequent incremental backups. |
Incremental backup | An incremental backup is a backup of only those blocks that have changed since a previous backup. Oracle lets you create and restore incremental backups of data files, tablespaces, and a database. You can include a control file in an incremental backup set, but the control file is always included in its entirety. No blocks are skipped. |
Multilevel incremental backup | RMAN lets you create multilevel backups. RMAN can create multilevel incremental backup. A value of 0 or 1 denotes each incremental level. A level 0 incremental backup, which is the base for subsequent incremental backups, copies all blocks containing data. You can create a level 0 database backup as backup sets or image copies. The only difference between a level 0 incremental backup and a full backup is that a full backup is never included in an incremental strategy. Thus, an incremental level 0 backup is a full backup that happens to be the parent of incremental backups whose level is greater than 0. The benefit to performing multilevel incremental backups is that you do not back up all of the blocks all of the time. Incremental backups at a level greater than zero (0) only copy the blocks that were modified. Hence, the backup size can be significantly smaller and the backup might require much less time. The size of the backup file depends solely upon the number of blocks that are modified and the incremental backup level. |
Differential incremental backup | In a differential level 1 backup, RMAN backs up all blocks that have changed since the most recent incremental backup at level 1 (cumulative or differential) or level 0. For example, in a differential level 1 backup, RMAN determines which level 1 backup is the most recent backup. RMAN backs up all blocks that have been modified after that backup. If no level 1 is available, then RMAN copies all blocks that have changed since the base level 0 backup. |
Cumulative incremental backup | In a cumulative level 1 incremental backup, RMAN backs up all blocks that have changed since the most recent backup at level 0. Cumulative incremental backups reduce the work that is needed for a restore. The cumulative incremental backup ensures that you only need one incremental backup from any particular level at restore time. Cumulative backups require more space and time than differential incremental backups, because they duplicate the work that previous backups did at the same level. |