Oracle Enhancements in RMAN

Oracle Tips by Burleson Consulting

This is an excerpt from "Oracle 10g New Features for Administrators" by Ahmed Baraka.

Configuration Changes

� When opening a database that was recovered using a backup or a current control file, the Oracle server automatically re-creates any locally managed temporary files if they do not exist. The files are recreated with the same creation size and storage settings. You can change the temporary file names by using the RMAN SET NEWNAME FOR TEMPFILE and SWITCH TEMPFILE command options.

� You no longer need to re-create the control file when any of the following configuration parameters are modified: MAXLOGFILES, MAXLOGMEMBERS, MAXINSTANCES. This ensures that you do not lose the RMAN catalog metadata through control file recreation, and reduces system down-time requirements.

� RMAN backups to backup sets do not back up never used blocks. In addition, Oracle Database 10g no longer backs up non-used blocks in locally managed tablespaces. Examples of such blocks are blocks that belong to dropped or truncated objects.

Using the BACKUP AS COPY Command

� The RMAN COPY command has been deprecated in Oracle Database 10g and replaced with BACKUP AS COPY command.

� BACKUP AS COPY command enables you to copy:

database, tablespaces, datafiles, archived redo logs and control files.

� If you want RMAN to create image copies by default (rather than backuset):

RMAN> configure device type disk backup type to copy

� To create a backup set in the command level:

RMAN> backup as backupset database

Performing Backups

RMAN> backup database;
RMAN> backup copy of database;
RMAN> backup tablespace users;
RMAN> backup copy of tablespace users;
RMAN> backup datafile 10;
RMAN> backup copy of datafile 10;
RMAN> backup current controlfile;
RMAN> backup controlfilecopy all;

Using the CATALOG Command

RMAN> catalog backuppiece 'filename'
RMAN> catalog datafilecopy 'filename'
RMAN> change backuppiece 'file_name' uncatalog

Using the CATALOG START WITH Command

You can ask the RMAN to search in a certain directory for all backup files that aren�t part of the catalog already:

RMAN> catalog start with "C:\ORACLE\FLASH_RECOVERY_AREA\NINA\DATAFILE"

Compressed Backups

� Oracle Database 10g lets you compress RMAN backups to save on storage.

� You must set the COMPATIBLE initialization parameter to a minimum of 10.0.0.

� You can�t compress an image copy; you can compress a backup only if you are using backup sets.

� The V$BACKUP_FILES view contains information on backup files including the compression status.

RMAN> CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET
RMAN> BACKUP AS COMPRESSED BACKUPSET DATABASE

Automatic Channel Failover

If one of the channels on which the RMAN is performing a backup fails, the RMAN will automatically try to use an alternative channel, provided you are using multiple channels.

Enhancements in RMAN Scripts

1. Convertibility of RMAN Scripts

In Oracle Database 10g, you can change a stored script into a text script and vice versa.

RMAN> print script full_backup to file 'my_script_file.txt'

2. Global RMAN Scripts

Oracle Database 10g provides a new concept of global scripts, which you can execute against any database registered in the recovery catalog, as long as your RMAN client is connected to the recovery catalog and a target database simultaneously.

RMAN> create global script global_full_backup
{ backup database plus archivelog;
delete obsolete; }