Backup Types

Full
- A backup that is not incremental.
- Includes all used data blocks in the datafiles
- Full backups of control files and archived logs always include all blocks in the files

Incremental
- A backup of datafiles that includes only the blocks that have changed since a previous incremental backup.
- Require a full or incremental level 0 backup to serve as a basis

Online
- A backup of online, read/write datafiles when the database is open

Closed
- A backup of any part of the target database when it is mounted but not open
- Can be consistent or inconsistent

Consistent
- A backup taken when the database in mounted(but not open) and was not crashed or shutdown with the ABORT option prior to mounting.
- The checkpoints SCNs in the datafile headers match the header information in the control file and none of the datafiles has changes beyond its checkpoint
- Can be restored without recovery

Inconsistent
- A backup of any part of the target database when
--- It is open
--- It crashed or a SHUTDOWN ABORT was run prior to mounting.
- Requires recovery to become consistent

A level 0 incremental backup
- the base for subsequent incremental backups, copies all blocks containing data.
- The only difference between a level 0 backup and a full backup is that a full backup is never included in an incremental strategy.

Incremental backup

A level n incremental backup in which n is greater than zero backs up either:
- All blocks changed after the most recent backup at level n or lower (the default type of incremental backup, which is called a differential backup)
- All blocks changed after the most recent backup at level n-1 or lower (called a cumulative backup)

Cumulative incremental backups
- reduce the work needed for a restore by ensuring that you only need one incremental backup from any particular level.
- Cumulative backups require more space and time than differential backups, however, because they duplicate the work done by previous backups at the same level.