Creating RMAN database to manage recovery catalog.

RMAN DBname: RMN1
tablespace name: rman_tbs
datafile name: rman01.dbf (size 100M)

on the prompt:
$ dbca &

step-1:
pick singel instance database on the Database Configuration Assistant: Welcome Screen.
step-2:
Pick Create a Database option
step-3:
Pick Custom Database on the database template. This is because you don't want any 
sample schemas in you RMAN database.
step-4:
Type "RMN1" rman database global name
Step-5:
Disselect "Configure the Database with Enterprise Manager" option, this is due to the 
fact that you're creating rman database to manage your recovery catalog and you don't
want to overload this small database with stuff unneccesary.
step-6:
Type password for sys/system login and save it in the safe place as we will require this
login credentials later to manage catalog database.
step-7:
Select "File System" option from Storage Mechanishm
step-8:
select "Use Database File Locations from template" option to choose for datafile 
storage or you can choose Oracle-Managed Files option.
step-9:
Make sure you Specify Flash Recovery Area
Step-10:
Choose appropriate memory for the rman database depending upon your need.
i go with about 300MB SGA size and 120MB for PGA.
Step-11:
Confirm the summary of parameters and other items and click Finish to start database creation.
Verify database creation:
$ export ORACLE_SID=RMN1
$ sqlplus rman/password@RMN1
Now you are ready to create rman recovery catalog database and register target database.
Go to the following link:

Creating a Rman Recovery Catalog

Creating a Recovery Catalog in RAC Environment

It is highly recommended that you create rman database in seperate server than having in the 
same server where RAC databases is intalled and are running. This would cause not only
performance issues but also if server crashes and data is not recoverable, you are going to
loose literally everything costing millions of dollors and hashles.

Create a RMAN database (RMN1)
=============================================================


Create a tablespace in the new database (RMN1)
============================================

$ sqlplus /nolog

CONNECT SYS/passwd@RMN1 AS SYSDBA;

CREATE TABLESPACE rman_tbs
DATAFILE '/u01/app/oracle/oradata/RMAN/rman01.dbf' size 100m;


Create the Recovery Catalog Owner in the new database (RMN1)
==============================================================

CREATE USER rman IDENTIFIED BY rman
DEFAULT TABLESPACE rman_tbs
QUOTA UNLIMITED ON rman_tbs;

Grant the necessary privileges to the schema owner(rman)
=============================================================

SQL> GRANT connect, resource, recovery_catalog_owner TO rman;

"RECOVERY_CATALOG_OWNER" role provides the user with all privileges required to maintain and query the recovery catalog

Creating the Recovery Catalog
==============================================================

Connect to the RMN1 database which will contain the recovery catalog. For example:

$ rman catalog rman/passwd@RMN1

Recovery Manager: Release 10.2.0.4.0 - Production on Mon Apr 10 18:22:00 2009
Copyright (c) 1982, 2005, Oracle. All rights reserved.
connected to recovery catalog database
RMAN>

Run the CREATE CATALOG command to create the catalog
======================================================

RMAN> CREATE CATALOG;

recovery catalog created

Registering a Database in the Recovery Catalog
=======================================================

Connect to the target database (ORCL) and recovery catalog database (RMN1).

$ export ORACLE_SID=ORCL; 

$ rman target / catalog rman/passwd@RMN1;

Recovery Manager: Release 10.2.0.4.0 - Production on Mon Apr 10 18:44:10 2009
Copyright (c) 1982, 2005, Oracle. All rights reserved.
connected to target database: ORCL (DBID=1679521370)
connected to recovery catalog database

RMAN> REGISTER DATABASE;

database registered in recovery catalog
starting full resync of recovery catalog
full resync complete

Make sure that the registration was successful by running REPORT SCHEMA:

RMAN> REPORT SCHEMA;

Now in RAC environment regardless of what node you are working on, you can use the same
networked rman database and rman user to take backup and manage other jobs.
if you have multiple databases installed then you must register each target database in
the recovery catalog to manage and maintain RMAN backups and other rman tasks. Here is how
you will register cluster databases:
$ export ORACLE_SID=DEV
$ rman target / catalog rman/passwd@RMN1;

RMAN> REGISTER DATABASE;

database registered in recovery catalog
starting full resync of recovery catalog
full resync complete

Make sure that the registration was successful by running REPORT SCHEMA:

RMAN> REPORT SCHEMA;

CRS-0184: Cannot communicate with CRS daemon.

Solution:
 a) check permission in raw devices
   # ls -lrt /dev/raw/raw*
 Permission should be for oracle user NOT for root. execute the following as 
 a root user.
chown oracle:oinstall /dev/raw/raw1
chown oracle:oinstall /dev/raw/raw2
chown oracle:oinstall /dev/raw/raw3
chown oracle:oinstall /dev/raw/raw4
chown oracle:oinstall /dev/raw/raw5
chmod 600 /dev/raw/raw1
chmod 600 /dev/raw/raw2
chmod 600 /dev/raw/raw3
chmod 600 /dev/raw/raw4
chmod 600 /dev/raw/raw5

Creating RMAN Recovery Catalog

Creating RMAN Database

How to Find DB Size in Oracle?

SELECT name, bytes 
from v$datafile;

OR

SELECT SUBSTR (df.NAME, 1, 40) file_name, df.bytes / 1024 / 1024 allocated_mb,
((df.bytes / 1024 / 1024) - NVL (SUM (dfs.bytes) / 1024 / 1024, 0))
used_mb,
NVL (SUM (dfs.bytes) / 1024 / 1024, 0) free_space_mb
FROM v$datafile df, dba_free_space dfs
WHERE df.file# = dfs.file_id(+)
GROUP BY dfs.file_id, df.NAME, df.file#, df.bytes
ORDER BY file_name;