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Consistent and Inconsistent Backups

A backup is either consistent or inconsistent. To make a consistent backup, your database must have been shut down cleanly and remain closed for the duration of the backup. Ali committed changes arc written to the data flles during the shut down process, so the data files are in a transaction-consistent State. When you restore your data files from a consistent backup, you can open the database immediatcly.

If the database is in ARCHIVELOG modę, then you can make inconsistent backups that

arc rccoverable using archived redo log files. Open database backups arc inconsistent bccause the onlinc redo log files contain changcs not yet applied to the data files. The onlinc redo log files must be archivcd and then backcd up with the data files to ensurc rccoverabiIity.

Despite the name, an inconsistent backup is as robust a form of backup as a consistent backup. The advantage of making inconsistent backups is that you can back up your database while the database is open for updates.