Oracle backup-Concepts

Oracle backup:

Backup is redundancy. In essence, it refers to copying a few copies of the current data to other places, so that when the original data file is damaged due to various reasons, we can use the backup file to restore the status of the backup.

Backup Type:

1. Physical backup (Physical Backups)

2. Logical backup (Logical Backups)

Physical backup refers to copying files. For oracle, it refers to copying data files, control files, archive files, and other physical files required for oracle Database startup to other places;

Implementation Method: RMAN and users manage backups

Logical backup copies data, no matter which files store data, means to export and store data to other locations through tools;

Implementation Method: exp, expdp, DBKINK + CREATE TABLE

Disadvantage: it is inefficient to process large data volumes and does not provide direct support for Incremental backup.

Backup in different database statuses:

An Online Backups database must be an inconsistent backup when it is enabled. If it is archived, it is a valid backup, also called an Online backup;

The Offline Backups database is normally shut down or in the read only status. It must be a consistent backup, which is a valid backup or Offline backup;

Backup status:

Consistent Backups: the backup data file and control file have the same SCN;

Inconsistent backup (Inconsistent Backups): the backup created when the database is in an Inconsistent state is Inconsistent backup;

Incremental Backup (Incremental Backups): For full backup, back up the files that change after the last full backup;

Differential backup (Differential Backups): For the last backup, no matter which backup is used, all files changed after the last backup are backed up;

Backup scale:

Full backup (whole database backups): includes data files, control files, archive files, and initialization parameter files. Archive mode and non-archive mode can be enabled. Backup is effective depending on the backup status;

Tablespace backups: backs up one or more tablespaces. In fact, it backs up data files belonging to tablespaces;

Data file backup (datafile buckups): backs up one or more data files;

Control backups ):

Archived redolog backups ):