The following graphic shows an example of how you can save the database instance DEMODB while it is running and then restore the data after a system breakdown using data and log backups.
Example: Backup and Restore
1. You create a complete data backup of the database instance DEMODB to a backup medium.
2. You activate automatic log backup. From now on, the database system continually creates log backups in backup files.
3. You create incremental data backups at regular intervals.
4. System failure occurs due to a hardware error in the hard disk containing the data area of the database instance. The hard disk that contains the log area, however, remains undamaged.
5. To restore the database instance, you proceed as follows:
a. You replace the defective hard disk.
b. You import the last complete data backup.
c. You import the last incremental data backup.
d. You import the log backups since the last incremental data backup. If there are still redo log entries in the undamaged log area, then the database system uses these redo log entries instead of the corresponding log backups.
6. The database system returns the database instance to the ONLINE operational state.
Database Administration Tutorial, Backup