Oracle Applications DBA Blog

RMAN for an APPS DBA

Its been long since i but up a post here. But have been tied up with a new project lately, i also apologize that i could not get back to your comments in time but will have them answered as soon as possible.
Also lately i have been working with RMAN, and found out that it has a steep learning curve but once you are through with the initial startup it actually is fun to use. RMAN or the Oracle Recovery Manager is a vast topic so i am just touching up the day to day commands that you might probably use and need to understand to get going.

Connecting to RMAN.
You can connect to the RMAN with or without the recovery catalog. there are multiple ways for connecting to RAMN.You can get the rman prompt by simply typing RMAN

RMAN>

you can connect to the target database either by using a username and password or with supplying the username and password as the database owner.

RMAN> connect target username/password@string
RMAN> connect target /

If you wish to connect to the rman catalog you can use the connect catalog command

RMAN> connect catalog username/password@string

To connect to an AUXILIARY database (maostly used for duplicating a database for cloning) use the CONNECT AUXILIARY command

RMAN> connect AUXILIARY username/password@string

again if you wish to connect as the owner of the AUXILIARY database you could use a '/'

RMAN> connect AUXILIARY /


RMAN CHANNELS

The ALLOCATE CHANNEL command is used to establish a channel between the RMAN and the database instance. You can either allocate a single channel for your whole backup job or specify multiple channels, once RMAN finishes the job with a  particular channel it releases that channel. The allocate channel is specified within the run braces.

Additionally you can use the DEVICE TYPE clause to  specify either a DISK to the channel or a TAPE.

RUN
{
  ALLOCATE CHANNEL c1 DEVICE TYPE sbt;
  ....................................

}

In the above case a channel is allocated for RAMN and the device type is TAPE.

Along with the ALLOCATE CHANNEL command you can also specify the PRAMS command to use the media management library of your media manager.

allocate channel ch1 type 'sbt_tape' parms
        'ENV=(TDPO_OPTFILE=/opt/tivoli/tsm/client/oracle/bin/tdpo.samdb)';

The above example shows the prams parameter for a Tivoli Storage Media.

BACKUP using RMAN
You can use the backup command to backup your database,tablespace, datafile , control file , SPFILE, archived log, or backup set.

To backup the database

RMAN>BACKUP DATABASE;

To backup individual tablespaces use the command

RMAN>BACKUP TABLESPACE GLD, GLX;

To backup database along with the archivelogs

RMAN>BACKUP DATABASE PLUS ARCHIVELOG;

To backup the SPFILE of the target database.

RMAN>BACKUP SPFILE:

To backup your controlfile

RMAN>BACKUP CURRENT CONTROLFILE;

You can also use the INCLUDE CONTROLFILE option to include the backup of your current control file along with any other backups you may perform.

RMAN>BACKUP DATABASE PLUS ARCHIVELOG INCLUDE CURRENT CONTROLFILE;

This backups your database, archive logs and also a copy of your current control file.

You could also TAG your backups by adding the TAG clause along with your BACKUP command.

RMAN>BACKUP DATABASE TAG = 'HOT SAMDB 050107 BACKUP'

Incremental Backups
You can have RMAN backup only the blocks that have changed after the last backup. There are two levels of incremental backups in RMAN.

Level 0 and Level 1

The Level 0 backup is almost similar to a full database backup. All subsequent incremental backups will be based on this backup.

The Level 1 backup is again categorized into types

Differential - This backs up all the blocks that have changed between the most recent level 1 or Level 0 backup
Cumulative - This backups all the blocks that have changed between the most recent level 0 backup.

By default incremental backups are differential

You must have Level 0 backup before you can use incremental backups.

RMAN>BACKUP INCREMENTAL LEVEL 0 DATABASE;

This creates a level 0 incremental backup of your database.

RMAN>BACKUP INCREMENTAL LEVEL 1 DATABASE;

This command will backup all the blocks that have changed since the last Level 0 or Level 1 backup.

Listing RMAN Backups

The LIST command is used for listing the backups taken from RMAN.

To list the backup of the database

RMAN>LIST BACKUP OF DATABASE;

To list a copy of a datafile

RMAN>LIST COPY OF DATAFILE 'sam/oradata/system01.dbf';

To list a backup of a database taken between two dates

RMAN>LIST BACKUP OF DATABASE COMPLETED BETWEEN '01-APR-2007' AND '08-MAY-2007';

you can also use the completed clause to list backup copies of datafiles between two dates.

To list backups by tag use

RMAN>LIST BACKUP TAG 'HOT SAMDB 050107 BACKUP';

REPORT

You can use the REPORT command to determine which are the files that need to be backed.

RMAN>REPORT NEED BACKUP;

This lists the files that need to be backed up based on the retention policy in place.

RMAN RESTORE

The RESTORE command can be used to restore backups from RMAN, you can restore a database, tablespace,  datafile , control file,SPFILE or archived log.

You can either allocate or configure channels for your restore operation or let RMAN allocate channels manually for the restore.

The following example shows a simple, complete database restore and recovery

RUN
{
  RESTORE DATABASE;
  RECOVER DATABASE;
}


This example show restoring a SPFILE

RMAN>RESTORE SPFILE

This will restore in the default location

RMAN>RESTORE SPFILE TO '/tmp/spfileTEMP.ora'

This will restore in a location other than the default.

Cloning with RMAN

If you are doing a hot cloning of your instance you can use RMAN do to the database cloning and then run adcfgclone with the DBTechStack option, as a part of your Oracle Applications cloning.

To clone an database using RMAN you must
Connect to the target (Source instance)
Connect to the recovery catalog
Connect to the auxiliary (to be cloned instance)

To restore the dbf files in the new server you cane use the SET NEWNAME FOR DATAFILE command within the RUN braces as below

run {
set newname for datafile 1 to '/u01/sam//oradata/sys01.dbf';
set newname for datafile 2 to ..............................

likewise for all your database files.

In the end use the DUPLICATE command to clone the database.

RMAN>duplicate target database to samcldb;