Oracle Non-archive mode vs. Archive mode backup

Inconsistent backup: Because the backup operation cannot be completed instantaneously, and the data files are written all the time, the SCN is changing, when the nth data file is backed up,

The SCN for the n+1 data file may have been different from the previous one.

Inconsistent backups must be repaired to a consistent state before they can be opened with archived log files and online redo logs after recovery. Therefore, the creation of

Build inconsistent backups In addition to the data files and control files that are required to back up the database, you need to back up the archive log files.

Consistent backup: Backed up data files and control files have the same SCN, which is a consistent backup. Only the database is closed in shutdown immediate mode

。 And a backup that is created when the database is not placed in an open state is a consistent backup.

A hot backup must be an inconsistency backup

When recovering from a hot backup to be created, it may be necessary to apply an archive log or online redo log to fix the database to a consistent state, as

This is to create a valid hot backup that requires the database to be in archive mode.

Whether the database is in archive mode does not affect the creation of a consistent backup, but only a consistent backup is a valid backup for non-archive databases.

Only an inconsistent backup created in archive mode can be considered a valid backup, and inconsistencies created in non-archive mode are most likely unrecoverable, or

Some data is lost after recovery.

For hot backup, the database must be in archive mode. Cold backup, the database can be in archive mode or in non-archive mode.

Oracle Non-archive mode vs. Archive mode backup