BACKUP

 

 

backup(oracle)

The following table illustrates the main types of physical backups and the non-RMAN methods for performing these backups.

Backup ObjectBackup MethodExample

Datafiles

Operating system utility

% cp df3.f df3.bak

Archived logs

Operating system utility

% cp log_1_23.arc log_1_23.bak

Control files

SQL statement

SQL> ALTER DATABASE BACKUP CONTROLFILE TO cf1.bak

Initialization parameter file

SQL statement

SQL> CREATE PFILE = init.ora.bak FROM SPFILE;

Network and password files

Operating system utility

% cp tnsnames.ora tnsnames.bak

C:/> copy tnsnames.ora tnsnames.bak

Logical objects (tables, indexes, PL/SQL units)

Export utility

% export SYSTEM/manager TABLE=hr.emp FILE=emp.dmp




 

 

 

Consistent and Inconsistent User-Managed Backups

You can use RMAN or operating system commands to make an inconsistent backup or a consistent backup. An inconsistent backup is a backup of one or more database files made while the database is open or after the database has not been shut down normally. A consistent backup is a backup of one or more database files that you make after the database has been shut down normally. Unlike an inconsistent backup, a consistent backup does not require recovery after it is restored.

A consistent whole database backup is the only valid backup option for databases running in NOARCHIVELOG mode, because otherwise redo needed for recovery is not available. In NOARCHIVELOG mode, Oracle overwrites redo records without archiving them first.

If you run the database in ARCHIVELOG mode, then you can back up database files while the database is open. These backups are inconsistent, but as long as you have the necessary archived redo logs you can recover these backups. You can either take a tablespace offline and back up its datafiles, or perform an online backup. An online backup occurs when the tablespace is still online. To perform an online backup, you must begin and end the backup with SQL statements that place the tablespace in and take the tablespace out of backup mode.