Duplicate a Database Using RMAN in Oracle Database 11g Release 2

• Introduction
• Backup-Based Duplication
• Active Database Duplication

Introduction

RMAN has the ability to duplicate, or clone, a database from a backup or from an active database. It is possible to create a duplicate database on a remote server with the same file structure, a remote server will a different file structure or the local server with a different file structure.

The article assumes the duplicate database is being created on a separate server, using the same SID (DB11G) and the same file structure as the source database. Explanations of several other scenarios are available here.

Backup-Based Duplication

Create a backup of the source database, if a suitable one doesn’t already exist.

$ rman target=/

RMAN> CONFIGURE CONTROLFILE AUTOBACKUP ON;
RMAN> BACKUP DATABASE PLUS ARCHIVELOG

All subsequent actions occur on the server running the duplicate database.

Create a password file for the duplicate instance.

$ orapwd file=/u01/app/oracle/product/11.2.0/db_1/dbs/orapwDB11G password=password entries=10

Add the appropriate entries into the “tnsnames.ora” file in the “$ORACLE_HOME/network/admin” directory to allow connections to the target database from the duplicate server.

# Added to the tnsnames.ora
DB11G-SOURCE =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = ol5-112-dup1)(PORT = 1521))
    )
    (CONNECT_DATA =
      (ORACLE_SID = DB11G)
    )
  )

Create a PFILE for the duplicate database. Since we are duplicating the database onto a separate server with the same filesystem as the original, we don’t need to convert the file names. In this case, the PFILE is called “initDB11G.ora” and is placed in the “$ORACLE_HOME/dbs” directory.

# Minimum Requirement.
DB_NAME=DB11G

# Convert file names to allow for different directory structure if necessary.
#DB_FILE_NAME_CONVERT=(/u01/app/oracle/oradata/DB11G/,/u01/app/oracle/oradata/NEWSID/)
#LOG_FILE_NAME_CONVERT=(/u01/app/oracle/oradata/DB11G/,/u02/app/oracle/oradata/NEWSID/)

Create any directories necessary for start the duplicate database.

$ mkdir -p /u01/app/oracle/oradata/DB11G
$ mkdir -p /u01/app/oracle/fast_recovery_area/DB11G
$ mkdir -p /u01/app/oracle/admin/DB11G/adump

Make the backup files from the source database available to the destination server. That can be done by either copying them to the matching location on the destination server, or placing them on a shared drive. If you are copying the files, you may want to use the following type of commands.

$ scp -r oracle@ol5-112-dup1:/u01/app/oracle/fast_recovery_area/DB11G/archivelog /u01/app/oracle/fast_recovery_area/DB11G
$ scp -r oracle@ol5-112-dup1:/u01/app/oracle/fast_recovery_area/DB11G/backupset /u01/app/oracle/fast_recovery_area/DB11G
$ scp -r oracle@ol5-112-dup1:/u01/app/oracle/fast_recovery_area/DB11G/autobackup /u01/app/oracle/fast_recovery_area/DB11G

Connect to the duplicate instance.

$ ORACLE_SID=DB11G; export ORACLE_SID
$ sqlplus / as sysdba

Start the database in NOMOUNT mode.

SQL> STARTUP NOMOUNT;

With the duplicate database started we can now connect to it from RMAN. For the duplication to work we must connect to the duplicate database (AUXILIARY), but depending on the type of duplication we are doing we may optionally connect to the original database (TARGET) and/or the recovery catalog (CATALOG).

$ ORACLE_SID=DB11G; export ORACLE_SID

$ rman AUXILIARY /
$ rman TARGET sys/password@DB11G-SOURCE AUXILIARY /
$ rman CATALOG rman/password@rman-catalog AUXILIARY /
$ rman TARGET sys/password@DB11G-SOURCE CATALOG rman/password@rman-catalog AUXILIARY /

We can then duplicate the database using one of the following commands.

# Backup files are in matching location to that on the source server.
# Duplicate database to TARGET's current state.
DUPLICATE TARGET DATABASE TO DB11G
  SPFILE
  NOFILENAMECHECK;

# Duplicate database to TARGET's state 4 days ago.
DUPLICATE TARGET DATABASE TO DB11G
  UNTIL TIME 'SYSDATE-4'
  SPFILE
  NOFILENAMECHECK;

# Backup files are in a different location to that on the source server.
# Duplicate database to the most recent state possible using the provided backups.
# Works with just an AUXILIARY connection only.
DUPLICATE DATABASE TO DB11G
  SPFILE
  BACKUP LOCATION '/source/app/oracle/fast_recovery_area/DB11G'
  NOFILENAMECHECK;

The time it takes to complete varies depending on the size of the database and the specification of the server. Once the process is finished RMAN produces a completion message and you have your duplicate instance.

Active Database Duplication

Oracle 11g introduced the ability to create duplicate databases directly without the need for a backup. This is known as active database duplication. The process is similar to the backup-based duplication, with a few exceptions.

First, and most obviously, you don’t need a backup of the source system, but it does have to be in ARCHIVELOG mode.

The passwords in the password files must match for both servers, so remember to set the correct password when creating the password file on the destination server.

Both the source and destination database servers require a “tnsnames.ora” entry for the destination database. In this case I added the following to each server. The destination server still requires the source entry shown in the previous section.

# Added to the tnsnames.ora on source and destination server.
DB11G-DESTINATION =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = ol5-112-dup2)(PORT = 1521))
    )
    (CONNECT_DATA =
      (ORACLE_SID = DB11G)
    )
  )

The destination server requires static listener configuration in a “listener.ora” file. In this case I used the following configuration. Remember to restart or reload the listener.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = DB11G.WORLD)
      (ORACLE_HOME = /u01/app/oracle/product/11.2.0/db_1)
      (SID_NAME = DB11G)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = ol5-112-dup2.localdomain)(PORT = 1521))
    )
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )

ADR_BASE_LISTENER = /u01/app/oracle

When connecting to RMAN, you must use a connect string for both the target and auxiliary connections.

$ ORACLE_SID=DB11G; export ORACLE_SID

$ rman TARGET sys/password@DB11G-SOURCE AUXILIARY sys/password@DB11G-DESTINATION

Include the FROM ACTIVE DATABASE clause in the DUPLICATE command.

DUPLICATE DATABASE TO DB11G
  FROM ACTIVE DATABASE
  SPFILE
  NOFILENAMECHECK;

For more information see:

• Duplicating a Database

Recovery Manager (RMAN)

Recovery manager is a platform non-specific utility for coordinating you backup and restoration procedures across multiple servers. In my opinion it’s value is limited if you only have on or two instances, but it comes into it’s own where large numbers of instances on multiple platforms are used. The reporting features alone mean that you should never find yourself in a position where your data is in danger due to failed backups.

The functionality of RMAN is too diverse to be covered in this article so I shall focus on the basic backup and recovery functionality.

• Create Recovery Catalog
• Register Database
• Cold Backup
• Hot Backup
• Restore & Recover The Whole Database
• Restore & Recover A Subset Of The Database
• Incomplete Recovery
• Lists And Reports

Create Recovery Catalog

First create a user to hold the recovery catalog:

CONNECT sys/password@TSH1

-- Create tablepsace to hold repository
CREATE TABLESPACE "TOOLS"
DATAFILE 'E:\ORACLE\ORADATA\DDBA1\TOOLS01.DBF' SIZE 10M
AUTOEXTEND ON NEXT 1024K
EXTENT MANAGEMENT LOCAL;

-- Create rman schema owner
CREATE USER rman IDENTIFIED BY rman
TEMPORARY TABLESPACE temp
DEFAULT TABLESPACE tools
QUOTA UNLIMITED ON tools;

GRANT connect, resource, recovery_catalog_owner TO rman;

Then create the recovery catalog:

c:> rman catalog rman/rman@tsh1

Recovery Manager: Release 8.1.7.0.0 - Production

RMAN-06008: connected to recovery catalog database
RMAN-06428: recovery catalog is not installed

RMAN> create catalog tablespace tools;

RMAN-06431: recovery catalog created

RMAN> exit

Recovery Manager complete.

C:>

Register Database

Each database to be backed up by RMAN must be registered:

C:>rman target sys/password@tsh1 rcvcat rman/rman@dba1 msglog 'C:OracleBackupTSH1TSH1_Daily_Backup.log'

Recovery Manager: Release 8.1.7.0.0 - Production

RMAN-06005: connected to target database: TSH1 (DBID=955315395)
RMAN-06008: connected to recovery catalog database

RMAN> register database;

RMAN-03022: compiling command: register
RMAN-03023: executing command: register
RMAN-08006: database registered in recovery catalog
RMAN-03023: executing command: full resync
RMAN-08002: starting full resync of recovery catalog
RMAN-08004: full resync complete

RMAN>

Existing user-created backups can be added to the catalog using:

catalog datafilecopy 'C:\Oracle\Oradata\TSH1.dbf';
catalog archivelog 'log1', 'log2', 'log3', ... 'logN';

Cold Backup

This RMAN script starts by doing a a clean mount of the database. It then backs up the datafiles, controlfile and archivelogs, with old archive logs deleted in the process. Finally the database is opened.

replace script 'TSH1_daily_backup' {

  # make sure database is shutdown cleanly
  shutdown immediate;
  startup force dba pfile=c:\Oracle\Admin\TSH1\pfile\init.ora;
  shutdown immediate;

  #Mount the database and start backup
  startup mount pfile=c:\Oracle\Admin\TSH1\pfile\init.ora;

  # Backup datafile, controlfile and archivelogs
  allocate channel ch1 type
    disk format 'C:\Oracle\Backup\TSH1\%d_DB_%u_%s_%p';
  backup database include current controlfile
    tag = 'TSH1_daily_backup';
  release channel ch1;

  # Open the database
  alter database open;

  # Archive all logfiles including current
  sql 'ALTER SYSTEM ARCHIVE LOG CURRENT'; 

  # Backup outdated archlogs and delete them
  allocate channel ch1 type
    disk format 'C:\Oracle\Backup\TSH1\%d_ARCH_%u_%s_%p';
  backup archivelog
    until time 'Sysdate-2' all
    delete input;
  release channel ch1;

  # Backup remaining archlogs
  allocate channel ch1 type
    disk format 'C:\Oracle\Backup\TSH1\%d_ARCH_%u_%s_%p';
  backup archivelog all;
  release channel ch1;

}

The file can be loaded as a stored script and run using the following commands:

RMAN> @c:\Oracle\Backup\TSH1_daily_backup.txt
RMAN> run {execute script TSH1_daily_backup; }

The RMAN output can be a bit unnerving at first. You should expect something like:

RMAN> run {execute script TSH1_daily_backup; }
RMAN-03021: executing script: TSH1_daily_backup

RMAN-03022: compiling command: shutdown
RMAN-06405: database closed
RMAN-06404: database dismounted
RMAN-06402: Oracle instance shut down

RMAN-03022: compiling command: startup
RMAN-06196: Oracle instance started
RMAN-06199: database mounted
RMAN-06400: database opened

Total System Global Area      13375516 bytes

Fixed Size                       75804 bytes
Variable Size                 12402688 bytes
Database Buffers                819200 bytes
Redo Buffers                     77824 bytes

RMAN-03022: compiling command: shutdown
RMAN-06405: database closed
RMAN-06404: database dismounted
RMAN-06402: Oracle instance shut down

RMAN-03022: compiling command: startup
RMAN-06193: connected to target database (not started)
RMAN-06196: Oracle instance started
RMAN-06199: database mounted

Total System Global Area      13375516 bytes

Fixed Size                       75804 bytes
Variable Size                 12402688 bytes
Database Buffers                819200 bytes
Redo Buffers                     77824 bytes

RMAN-03022: compiling command: allocate
RMAN-03023: executing command: allocate
RMAN-08030: allocated channel: ch1
RMAN-08500: channel ch1: sid=14 devtype=DISK

RMAN-03022: compiling command: backup
RMAN-03023: executing command: backup
RMAN-08008: channel ch1: starting full datafile backupset
RMAN-08502: set_count=51 set_stamp=437320255 creation_time=09-AUG-01
RMAN-08010: channel ch1: specifying datafile(s) in backupset
RMAN-08522: input datafile fno=00001 name=C:\ORACLE\ORADATA\TSH1\SYSTEM01.DBF
RMAN-08011: including current controlfile in backupset
RMAN-08522: input datafile fno=00009 name=C:\ORACLE\ORADATA\TSH1\DES601.DBF
RMAN-08522: input datafile fno=00002 name=C:\ORACLE\ORADATA\TSH1\RBS01.DBF
RMAN-08522: input datafile fno=00008 name=C:\ORACLE\ORADATA\TSH1\OEM_REPOSITORY.ORA
RMAN-08522: input datafile fno=00003 name=C:\ORACLE\ORADATA\TSH1\USERS01.DBF
RMAN-08522: input datafile fno=00004 name=C:\ORACLE\ORADATA\TSH1\TEMP01.DBF
RMAN-08522: input datafile fno=00006 name=C:\ORACLE\ORADATA\TSH1\INDX01.DBF
RMAN-08522: input datafile fno=00007 name=C:\ORACLE\ORADATA\TSH1\DR01.DBF
RMAN-08522: input datafile fno=00005 name=C:\ORACLE\ORADATA\TSH1\TOOLS01.DBF
RMAN-08013: channel ch1: piece 1 created
RMAN-08503: piece handle=C:\ORACLE\BACKUP\TSH1\TSH1_DB_1JD11UHV_51_1 comment=NONE
RMAN-08525: backup set complete, elapsed time: 00:05:52
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete

RMAN-03022: compiling command: release
RMAN-03023: executing command: release
RMAN-08031: released channel: ch1

RMAN-03022: compiling command: alter db
RMAN-06400: database opened

RMAN-03022: compiling command: sql
RMAN-06162: sql statement: ALTER SYSTEM ARCHIVE LOG CURRENT
RMAN-03023: executing command: sql

RMAN-03022: compiling command: allocate
RMAN-03023: executing command: allocate
RMAN-08030: allocated channel: ch1
RMAN-08500: channel ch1: sid=14 devtype=DISK

RMAN-03022: compiling command: backup
RMAN-03025: performing implicit partial resync of recovery catalog
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete
RMAN-03023: executing command: backup
RMAN-08009: channel ch1: starting archivelog backupset
RMAN-08502: set_count=52 set_stamp=437320626 creation_time=09-AUG-01
RMAN-08014: channel ch1: specifying archivelog(s) in backup set
RMAN-08504: input archivelog thread=1 sequence=226 recid=11 stamp=437307841
RMAN-08504: input archivelog thread=1 sequence=227 recid=12 stamp=437309722
RMAN-08504: input archivelog thread=1 sequence=228 recid=13 stamp=437316806
RMAN-08504: input archivelog thread=1 sequence=229 recid=14 stamp=437317665
RMAN-08504: input archivelog thread=1 sequence=230 recid=15 stamp=437319111
RMAN-08504: input archivelog thread=1 sequence=231 recid=16 stamp=437320622
RMAN-08013: channel ch1: piece 1 created
RMAN-08503: piece handle=C:\ORACLE\BACKUP\TSH1\TSH1_ARCH_1KD11UTI_52_1 comment=NONE
RMAN-08525: backup set complete, elapsed time: 00:00:04
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete

RMAN-03022: compiling command: release
RMAN-03023: executing command: release
RMAN-08031: released channel: ch1

RMAN> exit

Recovery Manager complete.

The recovery catalog should be resyncronized on a regular basis so that changes to the database structure and presence of new archive logs is recorded. Some commands perform partial and full resyncs implicitly, but a full resync should be scheduled at regular intervals.

resync catalog;

Hot Backup

Hot backups using RMAN are very simple. There is no need to alter the tablespace or database mode.

run {
  allocate channel ch1 type disk format 'd:\oracle\backup%d_DB_%u_%s_%p';
  backup database;
  backup archivelog all;
  release channel ch1;
}

Restore & Recover The Whole Database

Recovering from a media failure is as simple as:

run {
    startup mount pfile=c:\Oracle\Admin\TSH1\pfile\init.ora;

    allocate channel ch1 type disk;

    restore database;
    recover database;

    release channel ch1;
}

This will result in all datafiles being restored then recovered. RMAN will apply archive logs as necessary until the recovery is complete. The sort of results you should expect are:

Recovery Manager: Release 8.1.7.0.0 - Production

RMAN-06005: connected to target database: TSH1 (DBID=955315395)
RMAN-06008: connected to recovery catalog database

RMAN> run {
2>     startup mount pfile=c:\Oracle\Admin\TSH1\pfile\init.ora;
3>
4>     allocate channel ch1 type disk;
5>
6>     restore database;
7>     recover database;
8>
9>     release channel ch1;
10>}

RMAN-03022: compiling command: startup
RMAN-06193: connected to target database (not started)
RMAN-06196: Oracle instance started
RMAN-06199: database mounted

Total System Global Area      13375516 bytes

Fixed Size                       75804 bytes
Variable Size                 12402688 bytes
Database Buffers                819200 bytes
Redo Buffers                     77824 bytes

RMAN-03022: compiling command: allocate
RMAN-03023: executing command: allocate
RMAN-08030: allocated channel: ch1
RMAN-08500: channel ch1: sid=14 devtype=DISK

RMAN-03022: compiling command: restore

RMAN-03022: compiling command: IRESTORE
RMAN-03023: executing command: IRESTORE
RMAN-08016: channel ch1: starting datafile backupset restore
RMAN-08502: set_count=51 set_stamp=437320255 creation_time=09-AUG-01
RMAN-08089: channel ch1: specifying datafile(s) to restore from backup set
RMAN-08523: restoring datafile 00001 to C:\ORACLE\ORADATA\TSH1\SYSTEM01.DBF
RMAN-08523: restoring datafile 00002 to C:\ORACLE\ORADATA\TSH1\RBS01.DBF
RMAN-08523: restoring datafile 00003 to C:\ORACLE\ORADATA\TSH1\USERS01.DBF
RMAN-08523: restoring datafile 00004 to C:\ORACLE\ORADATA\TSH1\TEMP01.DBF
RMAN-08523: restoring datafile 00005 to C:\ORACLE\ORADATA\TSH1\TOOLS01.DBF
RMAN-08523: restoring datafile 00006 to C:\ORACLE\ORADATA\TSH1\INDX01.DBF
RMAN-08523: restoring datafile 00007 to C:\ORACLE\ORADATA\TSH1\DR01.DBF
RMAN-08523: restoring datafile 00008 to C:\ORACLE\ORADATA\TSH1\OEM_REPOSITORY.ORA
RMAN-08523: restoring datafile 00009 to C:\ORACLE\ORADATA\TSH1\DES601.DBF
RMAN-08023: channel ch1: restored backup piece 1
RMAN-08511: piece handle=C:\ORACLE\BACKUP\TSH1\TSH1_DB_1JD11UHV_51_1 tag=TSH1_DAILY_BACKUP params=NULL
RMAN-08024: channel ch1: restore complete
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete

RMAN-03022: compiling command: recover

RMAN-03022: compiling command: recover(1)

RMAN-03022: compiling command: recover(2)

RMAN-03022: compiling command: recover(3)
RMAN-03023: executing command: recover(3)
RMAN-08054: starting media recovery
RMAN-08055: media recovery complete

RMAN-03022: compiling command: recover(4)

RMAN-03022: compiling command: release
RMAN-03023: executing command: release
RMAN-08031: released channel: ch1

RMAN> exit

Recovery Manager complete.

Once this process us complete the database can be opened using the ALTER DATABASE OPEN; command.

Restore & Recover A Subset Of The Database

A subset of the database can be restored in a similar fashion:

run {
    sql 'ALTER TABLESPACE users OFFLINE IMMEDIATE';
    restore tablespace users;
    recover tablespace users;
    sql 'ALTER TABLESPACE users ONLINE';
}

Incomplete Recovery

As you would expect, RMAN allows incomplete recovery to a specified time, SCN or sequence number:

run
{
  set until time 'Nov 15 2000 09:00:00';
  # set until scn 1000;       # alternatively, you can specify SCN
  # set until sequence 9923;  # alternatively, you can specify log sequence number
  restore database;
  recover database;
}

alter database open resetlogs;

The incomplete recovery requires the database to be opened using the RESETLOGS option.

Lists And Reports

RMAN has extensive listing and reporting functionality allowing you to monitor you backups and maintain the recovery catalog. Here are a few useful commands:

# Show all backup details
list backup;

# Show items that beed 7 days worth of
# archivelogs to recover completely
report need backup days = 7 database;  

# Show/Delete items not needed for recovery
report obsolete;
delete obsolete;

# Show/Delete items not needed for point-in-time
# recovery within the last week
report obsolete recovery window of 7 days;
delete obsolete recovery window of 7 days;

# Show/Delete items with more than 2 newer copies available
report obsolete redundancy = 2 device type disk;
delete obsolete redundancy = 2 device type disk;

# Show datafiles that connot currently be recovered
report unrecoverable database;
report unrecoverable tablespace 'USERS';

It’s worth spending some time looking at all the reporting capabilities whilst deciding whether you should switch from shell scripting to RMAN. It might just influence your decision.

RMAN Enhancements in Oracle Database 10g

Oracle 10g includes many RMAN enhancements making it a more complete tool, including the following.

• Flash Recovery Area
• Incrementally Updated Backups
• Fast Incremental Backups
• BACKUP for Backupsets and Image Copies
• Cataloging Backup Pieces
• Improved RMAN Reporting Through V$ Views
• Automatic Instance Creation for RMAN TSPITR
• Cross-Platform Tablespace Conversion
• Enhanced Stored Scripts Commands
• Backupset Compression
• Restore Preview
• Managing Backup Duration and Throttling
• Miscellaneous
  • Disk Topology and Automatic Performance Tuning
  • Automatic Datafile Creation
  • Proxy Archived Log Backups
  • Recovery Through Restlogs
  • Restore Failover
  • Channel Failover
  • Deferred Error Reporting

Flash Recovery Area

The flash recovery area is a location on the filesystem or on an ASM disk group that holds files related to recovery.

• Multiplexed controlfiles
• Multiplexed online redo logs
• Archived redo logs
• Flashback logs
• RMAN disk backups
• Files created by RESTORE and RECOVERY commands.

Space within the flash recovery area is managed by the database. If there is not enough space to complete an operation obsolete, backed up or redundant files are removed to free up some space.

The following example shows the parameters used to configure the flash recovery area.

ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE = 2G;
ALTER SYSTEM SET DB_RECOVERY_FILE_DEST = '/u01/app/oracle/flash_recovery_area';
ALTER SYSTEM SET DB_FLASHBACK_RETENTION_TARGET = 1440;

The flashback technologies are covered in the Flashback New Features and Enhancements in Oracle Database 10g article.

Incrementally Updated Backups

Using this feature all changes between the SCN of the original image copy and the SCN of the incremental backup are applied to the image copy, winding it forward to make the equivalent of a new database image copy without the overhead of such a backup. The following example shows how this can be used.

RUN {
  RECOVER COPY OF DATABASE WITH TAG 'incr_backup' UNTIL TIME 'SYSDATE - 7';
  BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG 'incr_backup' DATABASE;
}

The RECOVER COPY... line will not do anything until the script has been running for more than 7 days. The BACKUP INCREMENTAL line will perform a complete backup (level 0) the first day it is run, with all subsequent backups being level 1 incremental backups. After 7 days, the RECOVER COPY... line will start to take effect, merging all incremental backups older than 7 days into the level 0 backup, effectively moving the level 0 backup forward. The effect of this is that you will permanently have a 7 day recovery window with a 7 day old level 0 backup and 6 level 1 incremental backups. Notice that the tag must be used to identify which incremental backups apply to which image copies.

If you wanted to keep your image copy as up to date as possible you might do the following.

RUN {
  BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG 'incr_backup' DATABASE;
  RECOVER COPY OF DATABASE WITH TAG 'incr_backup';
}

In this example the incremental backup is merged into the image copy as soon as it is completed.

Fast Incremental Backups

There are performance issues associated with incremental backups as the whole of each datafile must be scanned to identify changed blocks. In Oracle 10g it is possible to track changed blocks using a change tracking file. Enabling change tracking does produce a small overhead, but it greatly improves the performance of incremental backups. The current change tracking status can be displayed using the following query.

SELECT status FROM v$block_change_tracking;

Change tracking is enabled using the ALTER DATABASE command.

ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;

By default the change tracking file is created as an Oracle Managed File (OMF) in the location pointed to by the DB_CREATE_FILE_DEST parameter. An alternate location can be specified using the following command.

ALTER DATABASE ENABLE BLOCK CHANGE TRACKING
  USING FILE '/u01/oradata/MYSID/rman_change_track.f' REUSE;

The tracking file is created with a minumum size of 10M and grows in 10M increments. It’s size is typically 1/30,000 the size of the datablocks to be tracked.

Change tracking can be disabled using the following command.

ALTER DATABASE DISABLE BLOCK CHANGE TRACKING;

Renaming or moving a tracking file can be accomplished in the normal way using the ALTER DATABASE RENAME FILE command. If the instance cannot be restarted you can simply disable and re-enable change tracking to create a new file. This method does result in the loss of any current change information.

BACKUP for Backupsets and Image Copies

In Oracle 10g the BACKUP command has been extended to allow it to initiate backups of image copies in addition to backupsets. As a result the COPY command has been deprecated in favour of this new syntax.

BACKUP AS COPY DATABASE;
BACKUP AS COPY TABLESPACE users;
BACKUP AS COPY DATAFILE 1;

RMAN supports the creation of image copies of datafiles and datafile copies, control files and controlfile copies, archived redo logs, and backup pieces.