General Backup and Recovery Questions

8/6/2019 General Backup and Recovery Questions

1/16

General Backup and Recovery questions

[edit] Why and when should I backup my database?

Backup and recovery is one of the most important aspects of a DBAs job. If you lose your

company's data, you could very well lose your job. Hardware and software can always be

replaced, but your data may be irreplaceable!

Normally one would schedule a hierarchy of daily, weekly and monthly backups, however

consult with your users before deciding on a backup schedule. Backup frequency normally

depends on the following factors:

Rate of data change/ transaction rate

Database availability/ Can you shutdown for cold backups?

Criticality of the data/ Value of the data to the company Read-only tablespace needs backing up just once right after you make it read-only

If you are running in archivelog mode you can backup parts of a database over an

extended cycle of days

If archive logging is enabled one needs to backup archived log files timeously to

prevent database freezes

Etc.

Carefully plan backup retention periods. Ensure enough backup media (tapes) are available

and that old backups are expired in-time to make media available for new backups. Off-site

vaulting is also highly recommended.

Frequently test your ability to recover and document all possible scenarios. Remember, it's

the little things that will get you. Most failed recoveries are a result of organizational errors

and miscommunication.

[edit] What strategies are available for backing-up an Oracle database?

The following methods are valid for backing-up an Oracle database:

Export/Import - Exports are "logical" database backups in that they extract logical

definitions and data from the database to a file. See the Import/ Export FAQ for more

details.

Cold or Off-line Backups - shut the database down and backup up ALL data, log,

and control files.
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=2http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=3http://www.orafaq.com/wiki/Import/_Export_FAQhttp://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=3http://www.orafaq.com/wiki/Import/_Export_FAQhttp://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=2


2/16

Hot or On-line Backups - If the database is available and in ARCHIVELOG mode, set

the tablespaces into backup mode and backup their files. Also remember to backup the

control files and archived redo log files.

RMAN Backups - while the database is off-line or on-line, use the "rman" utility to

backup the database.

It is advisable to use more than one of these methods to backup your database. For

example, if you choose to do on-line database backups, also cover yourself by doing

database exports. Also test ALL backup and recovery scenarios carefully. It is better to be

safe than sorry.

Regardless of your strategy, also remember to backup all required software libraries,

parameter files, password files, etc. If your database is in ARCHIVELOG mode, you also need

to backup archived log files.

[edit] What is the difference between online and offline backups?

A hot (or on-line) backup is a backup performed while the database is open and available for

use (read and write activity). Except for Oracle exports, one can only do on-line backups

when the database is ARCHIVELOG mode.

A cold (or off-line) backup is a backup performed while the database is off-line and

unavailable to its users. Cold backups can be taken regardless if the database is in

ARCHIVELOG or NOARCHIVELOG mode.

It is easier to restore from off-line backups as no recovery (from archived logs) would be

required to make the database consistent. Nevertheless, on-line backups are less disruptive

and doesn't require database downtime.

Point-in-time recovery (regardless if you do on-line or off-line backups) is only available

when the database is in ARCHIVELOG mode.

[edit] What is the difference between restoring and recovering?

Restoring involves copying backup files from secondary storage (backup media) to disk. Thiscan be done to replace damaged files or to copy/move a database to a new location.

Recovery is the process of applying redo logs to the database to roll it forward. One can roll-

forward until a specific point-in-time (before the disaster occurred), or roll-forward until the

last transaction recorded in the log files.
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=4http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=5http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=4http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=5


3/16

SQL> connect SYS as SYSDBA

SQL> RECOVER DATABASE UNTIL TIME '2001-03-06:16:00:00' USING BACKUP CONTROLFILE;

RMAN> run {

set until time to_date('04-Aug-2004 00:00:00', 'DD-MON-YYYY HH24:MI:SS');

restore database;

recover database;

}

[edit] My database is down and I cannot restore. What now?

This is probably not the appropriate time to be sarcastic, but, recovery without backups are

not supported. You know that you should have tested your recovery strategy, and that you

should always backup a corrupted database before attempting to restore/recover it.

Nevertheless, Oracle Consulting can sometimes extract data from an offline database using

a utility called DUL (Disk UnLoad - Life is DUL without it!). This utility reads data in the datafiles and unloads it into SQL*Loader or export dump files. Hopefully you'll then be able to

load the data into a working database.

Note that DUL does not care about rollback segments, corrupted blocks, etc, and can thus

not guarantee that the data is not logically corrupt. It is intended as an absolute last resort

and will most likely cost your company a lot of money!

DUDE (Database Unloading by Data Extraction) is another non-Oracle utility that can be

used to extract data from a dead database. More info about DUDE is available at

http://www.ora600.nl/.

[edit] How does one backup a database using the export utility?

Oracle exports are "logical" database backups (not physical) as they extract data and logical

definitions from the database into a file. Other backup strategies normally back-up the

physical data files.

One of the advantages of exports is that one can selectively re-import tables, however one

cannot roll-forward from an restored export. To completely restore a database from an

export file one practically needs to recreate the entire database.

Always do full system level exports (FULL=YES). Full exports include more information about

the database in the export file than user level exports. For more information about the

Oracle export and import utilities, see the Import/ Export FAQ.

[edit] How does one put a database into ARCHIVELOG mode?
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=6http://www.ora600.nl/http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=7http://www.orafaq.com/wiki/Import/_Export_FAQhttp://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=8http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=6http://www.ora600.nl/http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=7http://www.orafaq.com/wiki/Import/_Export_FAQhttp://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=8


4/16

The main reason for running in archivelog mode is that one can provide 24-hour availability

and guarantee complete data recoverability. It is also necessary to enable ARCHIVELOG

mode before one can start to use on-line database backups.

Issue the following commands to put a database into ARCHVELOG mode:

SQL> CONNECT sys AS SYSDBA

SQL> STARTUP MOUNT EXCLUSIVE;

SQL> ALTER DATABASE ARCHIVELOG;

SQL> ARCHIVE LOG START;

SQL> ALTER DATABASE OPEN;

Alternatively, add the above commands into your database's startup command script, and

bounce the database.

The following parameters needs to be set for databases in ARCHIVELOG mode:

log_archive_start = TRUE

log_archive_dest_1 = 'LOCATION=/arch_dir_name'

log_archive_dest_state_1 = ENABLE

log_archive_format = %d_%t_%s.arc

NOTE 1: Remember to take a baseline database backup right after enabling archivelog

mode. Without it one would not be able to recover. Also, implement an archivelog backup to

prevent the archive log directory from filling-up.

NOTE 2:' ARCHIVELOG mode was introduced with Oracle 6, and is essential for database

point-in-time recovery. Archiving can be used in combination with on-line and off-line

database backups.

NOTE 3: You may want to set the following INIT.ORA parameters when enabling

ARCHIVELOG mode: log_archive_start=TRUE, log_archive_dest=..., and

log_archive_format=...

NOTE 4: You can change the archive log destination of a database on-line with theARCHIVE

LOG START TO 'directory'; statement. This statement is often used to switch archiving

between a set of directories.

NOTE 5: When running Oracle Real Application Clusters (RAC), you need to shut down all

nodes before changing the database to ARCHIVELOG mode. See the RAC FAQ for more

details.
http://www.orafaq.com/wiki/Bouncehttp://www.orafaq.com/wiki/Oracle_6http://www.orafaq.com/wiki/Oracle_6http://www.orafaq.com/wiki/RAC_FAQhttp://www.orafaq.com/wiki/Bouncehttp://www.orafaq.com/wiki/Oracle_6http://www.orafaq.com/wiki/RAC_FAQ


5/16

[edit] I've lost an archived/online REDO LOG file, can I get my DB back?

The following INIT.ORA/SPFILE parameter can be used if your current redologs are corrupted

or blown away. It may also be handy if you do database recovery and one of the archived

log files are missing and cannot be restored.

NOTE: Caution is advised when enabling this parameter as you might end-up losing your

entire database. Please contact Oracle Support before using it.

_allow_resetlogs_corruption = true

This should allow you to open the database. However, after using this parameter your

database will be inconsistent (some committed transactions may be lost or partially

applied).

Steps:

Do a "SHUTDOWN NORMAL" of the database

Set the above parameter

Do a "STARTUP MOUNT" and "ALTER DATABASE OPEN RESETLOGS;"

If the database asks for recovery, use an UNTIL CANCEL type recovery and apply all

available archive and on-line redo logs, then issue CANCEL and reissue the "ALTER

DATABASE OPEN RESETLOGS;" command.

Wait a couple of minutes for Oracle to sort itself out

Do a "SHUTDOWN NORMAL"

Remove the above parameter!

Do a database "STARTUP" and check your ALERT.LOG file for errors.

Extract the data and rebuild the entire database

[edit] User managed backup and recovery

This section deals with user managed, or non-RMAN backups.

[edit] How does one do off-line database backups?

Shut down the database from sqlplus or server manager. Backup all files to secondary

storage (eg. tapes). Ensure that you backup all data files, all control files and all log files.

When completed, restart your database.

Do the following queries to get a list of all files that needs to be backed up:
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=9http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=10http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=11http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=9http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=10http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=11


6/16

select name from sys.v_$datafile;

select member from sys.v_$logfile;

select name from sys.v_$controlfile;[/code]

Sometimes Oracle takes forever to shutdown with the "immediate" option. As workaround to

this problem, shutdown using these commands:

alter system checkpoint;

shutdown abort

startup restrict

shutdown immediate

Note that if you database is in ARCHIVELOG mode, one can still use archived log files to roll

forward from an off-line backup. If you cannot take your database down for a cold (off-line)

backup at a convenient time, switch your database into ARCHIVELOG mode and perform hot

(on-line) backups.

[edit] How does one do on-line database backups?

Each tablespace that needs to be backed-up must be switched into backup mode before

copying the files out to secondary storage (tapes). Look at this simple example.

ALTER TABLESPACE xyz BEGIN BACKUP;

! cp xyfFile1 /backupDir/

ALTER TABLESPACE xyz END BACKUP;

It is better to backup tablespace for tablespace than to put all tablespaces in backup mode.

Backing them up separately incurs less overhead. When done, remember to backup your

control files. Look at this example:

ALTER SYSTEM SWITCH LOGFILE; -- Force log switch to update control file headers

ALTER DATABASE BACKUP CONTROLFILE TO '/backupDir/control.dbf';

NOTE: Do not run on-line backups during peak processing periods. Oracle will write complete

database blocks instead of the normal deltas to redo log files while in backup mode. This will

lead to excessive database archiving and even database freezes.

[edit] My database was terminated while in BACKUP MODE, do I need to recover?

If a database was terminated while one of its tablespaces was in BACKUP MODE (ALTER

TABLESPACE xyz BEGIN BACKUP;), it will tell you that media recovery is required when you
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=12http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=13http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=12http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=13


7/16


8/16

RMAN can do off-line and on-line database backups. It cannot, however, write directly to

tape, but various 3rd-party tools (like Veritas, Omiback, etc) can integrate with RMAN to

handle tape library management.

RMAN can be operated from Oracle Enterprise Manager, or from command line. Here are the

command line arguments:

Argument Value Description

-----------------------------------------------------------------------------

target quoted-string connect-string for target database

catalog quoted-string connect-string for recovery catalog

nocatalog none if specified, then no recovery catalog

cmdfile quoted-string name of input command file

log quoted-string name of output message log file

trace quoted-string name of output debugging message log file

append none if specified, log is opened in append modedebug optional-args activate debugging

msgno none show RMAN-nnnn prefix for all messages

send quoted-string send a command to the media manager

pipe string building block for pipe names

timeout integer number of seconds to wait for pipe input

-----------------------------------------------------------------------------

Here is an example:

[oracle@localhost oracle]$ rman

Recovery Manager: Release 10.1.0.2.0 - ProductionCopyright (c) 1995, 2004, Oracle. All rights reserved.

RMAN> connect target;

connected to target database: ORCL (DBID=1058957020)

RMAN> backup database;

...

[edit] How does one backup and restore a database using RMAN?

The biggest advantage of RMAN is that it only backup used space in the database. RMAN

doesn't put tablespaces in backup mode, saving on redo generation overhead. RMAN will re-

read database blocks until it gets a consistent image of it. Look at this simple backup

example.
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=17http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=17


9/16

rman target sys/*** nocatalog

run {

allocate channel t1 type disk;

backup

format '/app/oracle/backup/%d_t%t_s%s_p%p'

(database);

release channel t1;

}

Example RMAN restore:

rman target sys/*** nocatalog

run {

allocate channel t1 type disk;

# set until time 'Aug 07 2000 :51';

restore tablespace users;recover tablespace users;

release channel t1;

}

The examples above are extremely simplistic and only useful for illustrating basic concepts.

By default Oracle uses the database controlfiles to store information about backups.

Normally one would rather setup a RMAN catalog database to store RMAN metadata in. Read

the Oracle Backup and Recovery Guide before implementing any RMAN backups.

Note: RMAN cannot write image copies directly to tape. One needs to use a third-party

media manager that integrates with RMAN to backup directly to tape. Alternatively one can

backup to disk and then manually copy the backups to tape.

[edit] How does one backup and restore archived log files?

One can backup archived log files using RMAN or any operating system backup utility.

Remember to delete files after backing them up to prevent the archive log directory from

filling up. If the archive log directory becomes full, your database will hang! Look at this

simple RMAN backup scripts:

RMAN> run {

2> allocate channel dev1 type disk;

3> backup

4> format '/app/oracle/archback/log_%t_%sp%p'

5> (archivelog all delete input);

6> release channel dev1;


10/16

7> }

The "delete input" clause will delete the archived logs as they as backed-up.

List all archivelog backups for the past 24 hours:

RMAN> LIST BACKUP OF ARCHIVELOG FROM TIME 'sysdate-1';

Here is a restore example:

RMAN> run {

2> allocate channel dev1 type disk;

3> restore (archivelog low logseq 78311 high logseq 78340 thread 1 all);

4> release channel dev1;

5> }

[edit] How does one create a RMAN recovery catalog?

Start by creating a database schema (usually called rman). Assign an appropriate

tablespace to it and grant it the recovery_catalog_ownerrole. Look at this example:

sqlplus sys

SQL> create user rman identified by rman;

SQL> alter user rman default tablespace tools temporary tablespace temp;

SQL> alter user rman quota unlimited on tools;

SQL> grant connect, resource, recovery_catalog_owner to rman;

SQL> exit;

Next, log in to rman and create the catalog schema. Prior to Oracle 8i this was done by

running the catrman.sql script.

rman catalog rman/rman

RMAN> create catalog tablespace tools;

RMAN> exit;

You can now continue by registering your databases in the catalog. Look at this example:

rman catalog rman/rman target backdba/backdba

RMAN> register database;
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=19http://www.orafaq.com/wiki/Oracle_8ihttp://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=19http://www.orafaq.com/wiki/Oracle_8i


11/16

One can also use the "upgrade catalog;" command to upgrade to a new RMAN release, or

the "drop catalog;" command to remove an RMAN catalog. These commands need to be

entered twice to confirm the operation.

[edit] How does one integrate RMAN with third-party Media Managers?

The following Media Management Software Vendors have integrated their media

management software with RMAN (Oracle Recovery Manager):

Veritas NetBackup - http://www.veritas.com/

EMC Data Manager (EDM) -http://www.emc.com/

HP OMNIBack/ DataProtector - http://www.hp.com/

IBM's Tivoli Storage Manager (formerly ADSM) - http://www.tivoli.com/storage/

EMC Networker - http://www.emc.com/

BrightStor ARCserve Backup - http://www.ca.com/us/data-loss-prevention.aspx

Sterling Software's SAMS:Alexandria (formerly from Spectralogic) -

http://www.sterling.com/sams/

SUN's Solstice Backup - http://www.sun.com/software/whitepapers/backup-n-storage/

CommVault Galaxy - http://www.commvault.com/

etc...

The above Media Management Vendors will provide first line technical support (and

installation guides) for their respective products.

A complete list of supported Media Management Vendors can be found at:

http://www.oracle.com/technology/deploy/availability/htdocs/bsp.htm

When allocating channels one can specify Media Management spesific parameters. Here are

some examples:

Netbackup on Solaris:

allocate channel t1 type 'SBT_TAPE'

PARMS='SBT_LIBRARY=/usr/openv/netbackup/bin/libobk.so.1';

Netbackup on Windows:

allocate channel t1 type 'SBT_TAPE' send "NB_ORA_CLIENT=client_machine_name";
http://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=20http://www.veritas.com/http://www.veritas.com/http://www.emc.com/http://www.emc.com/http://www.emc.com/http://www.hp.com/http://www.hp.com/http://www.tivoli.com/storage/http://www.tivoli.com/storage/http://www.emc.com/http://www.ca.com/us/data-loss-prevention.aspxhttp://www.ca.com/us/data-loss-prevention.aspxhttp://www.sterling.com/sams/http://www.sun.com/software/whitepapers/backup-n-storage/http://www.commvault.com/http://www.oracle.com/technology/deploy/availability/htdocs/bsp.htmhttp://www.orafaq.com/wiki/index.php?title=Oracle_database_Backup_and_Recovery_FAQ&action=edit&section=20http://www.veritas.com/http://www.emc.com/http://www.hp.com/http://www.tivoli.com/storage/http://www.emc.com/http://www.ca.com/us/data-loss-prevention.aspxhttp://www.sterling.com/sams/http://www.sun.com/software/whitepapers/backup-n-storage/http://www.commvault.com/http://www.oracle.com/technology/deploy/availability/htdocs/bsp.htm


12/16

Omniback/ DataProtector on HP-UX:

allocate channel t1 type 'SBT_TAPE' PARMS='SBT_LIBRARY=

/opt/omni/lib/libob2oracle8_64bit.sl';

or:

allocate channel 'dev_1' type 'sbt_tape' parms

'ENV=OB2BARTYPE=Oracle8,OB2APPNAME=orcl,OB2BARLIST=machinename_orcl_archlogs)'

;

[edit] How does one clone/duplicate a database with RMAN?

The first step to clone or duplicate a database with RMAN is to create a new INIT.ORA and

password file (use the orapwd utility) on the machine you need to clone the database to.

Review all parameters and make the required changed. For example, set the DB_NAME

parameter to the new database's name.

Secondly, you need to change your environment variables, and do a STARTUP NOMOUNT

from sqlplus. This database is referred to as the AUXILIARY in the script below.

Lastly, write a RMAN script like this to do the cloning, and call it with "rman cmdfile

dupdb.rcv":

connect target sys/secure@origdb

connect catalog rman/rman@catdbconnect auxiliary /

run {

set newname for datafile 1 to '/ORADATA/u01/system01.dbf';

set newname for datafile 2 to '/ORADATA/u02/undotbs01.dbf';

set newname for datafile 3 to '/ORADATA/u03/users01.dbf';

set newname for datafile 4 to '/ORADATA/u03/indx01.dbf';

set newname for datafile 5 to '/ORADATA/u02/example01.dbf';

allocate auxiliary channel dupdb1 type disk;

set until sequence 2 thread 1;

duplicate target database to dupdb

logfile

GROUP 1 ('/ORADATA/u02/redo01.log') SIZE 200k REUSE,

GROUP 2 ('/ORADATA/u03/redo02.log') SIZE 200k REUSE;

}


13/16

The above script will connect to the "target" (database that will be cloned), the recovery

catalog (to get backup info), and the auxiliary database (new duplicate DB). Previous

backups will be restored and the database recovered to the "set until time" specified in the

script.

Notes: the "set newname" commands are only required if your datafile names will different

from the target database.

The newly cloned DB will have its own unique DBID.

[edit] Can one restore RMAN backups without a CONTROLFILE and RECOVERY

CATALOG?

Details of RMAN backups are stored in the database control files and optionally a Recovery

Catalog. If both these are gone, RMAN cannot restore the database. In such a situation one

must extract a control file (or other files) from the backup pieces written out when the last

backup was taken. Let's look at an example:

Let's take a backup (partial in our case for ilustrative purposes):

$ rman target / nocatalog

Recovery Manager: Release 10.1.0.2.0 - 64bit Production

Copyright (c) 1995, 2004, Oracle. All rights reserved.

connected to target database: ORCL (DBID=1046662649)

using target database controlfile instead of recovery catalog

RMAN> backup datafile 1;

Starting backup at 20-AUG-04

allocated channel: ORA_DISK_1

channel ORA_DISK_1: sid=146 devtype=DISK

channel ORA_DISK_1: starting full datafile backupset

channel ORA_DISK_1: specifying datafile(s) in backupset

input datafile fno=00001 name=/oradata/orcl/system01.dbf

channel ORA_DISK_1: starting piece 1 at 20-AUG-04

channel ORA_DISK_1: finished piece 1 at 20-AUG-04

piece handle=

/

flash_recovery_area/ORCL/backupset/2004_08_20/o1_mf_nnndf_TAG20040820T153256_0lcz

d9tf_.bkp comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:45

channel ORA_DISK_1: starting full datafile backupset

channel ORA_DISK_1: specifying datafile(s) in backupset

including current controlfile in backupset


14/16

including current SPFILE in backupset

channel ORA_DISK_1: starting piece 1 at 20-AUG-04

channel ORA_DISK_1: finished piece 1 at 20-AUG-04

piece handle=

/

flash_recovery_area/ORCL/backupset/2004_08_20/o1_mf_ncsnf_TAG20040820T153256_0lczf

rx8_.bkp comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:04

Finished backup at 20-AUG-04[/code]

Now, let's destroy one of the control files:

SQL> show parameters CONTROL_FILES

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

control_files string /oradata/orcl/control01.ctl,/oradata/orcl/control02.ctl,

/oradata/orcl/control03.ctl

SQL> shutdown abort;

ORACLE instance shut down.

SQL> ! mv /oradata/orcl/control01.ctl /tmp/control01.ctl

Now, let's see if we can restore it. First we need to start the databaase in NOMOUNT mode:

SQL> startup NOMOUNT

ORACLE instance started.

Total System Global Area 289406976 bytes

Fixed Size 1301536 bytes

Variable Size 262677472 bytes

Database Buffers 25165824 bytes

Redo Buffers 262144 bytes

Now, from SQL*Plus, run the following PL/SQL block to restore the file:

DECLARE

v_devtype VARCHAR2(100);v_done BOOLEAN;

v_maxPieces NUMBER;

TYPE t_pieceName IS TABLE OF varchar2(255) INDEX BY binary_integer;

v_pieceName t_pieceName;

BEGIN


15/16

-- Define the backup pieces... (names from the RMAN Log file)

v_pieceName(1) :=

'/flash_recovery_area/ORCL/backupset/2004_08_20/o1_mf_ncsnf_TAG20040820T153256_

0lczfrx8_.bkp';

v_pieceName(2) :=

'/flash_recovery_area/ORCL/backupset/2004_08_20/o1_mf_nnndf_TAG20040820T153256_

0lczd9tf_.bkp';

v_maxPieces := 2;

-- Allocate a channel... (Use type=>null for DISK, type=>'sbt_tape' for TAPE)

v_devtype := DBMS_BACKUP_RESTORE.deviceAllocate(type=>NULL, ident=>'d1');

-- Restore the first Control File...

DBMS_BACKUP_RESTORE.restoreSetDataFile;

-- CFNAME mist be the exact path and filename of a controlfile taht was backed-up

DBMS_BACKUP_RESTORE.restoreControlFileTo(cfname=>'/app/oracle/oradata/orcl/control01.ctl');

dbms_output.put_line('Start restoring '||v_maxPieces||' pieces.');

FOR i IN 1..v_maxPieces LOOP

dbms_output.put_line('Restoring from piece '||v_pieceName(i));

DBMS_BACKUP_RESTORE.restoreBackupPiece(handle=>v_pieceName(i), done=>v_done,

params=>null);

exit when v_done;

END LOOP;

-- Deallocate the channel...

DBMS_BACKUP_RESTORE.deviceDeAllocate('d1');

EXCEPTION

WHEN OTHERS THEN

DBMS_BACKUP_RESTORE.deviceDeAllocate;

RAISE;

END;

/

Let's see if the controlfile was restored:

SQL> ! ls -l /oradata/orcl/control01.ctl-rw-r----- 1 oracle dba 3096576 Aug 20 16:45 /oradata/orcl/control01.ctl[/code]

We should now be able to MOUNT the database and continue recovery...

SQL> ! cp /oradata/orcl/control01.ctl /oradata/orcl/control02.ctl


16/16

SQL> ! cp /oradata/orcl/control01.ctl /oradata/orcl/control03.ctl

SQL> alter database mount;

SQL> recover database using backup controlfile;

ORA-00279: change 7917452 generated at 08/20/2004 16:40:59 needed for thread 1

ORA-00289: suggestion :

/flash_recovery_area/ORCL/archivelog/2004_08_20/o1_mf_1_671_%u_.arc

ORA-00280: change 7917452 for thread 1 is in sequence #671

Specify log: {=suggested | filename | AUTO | CANCEL}

/oradata/orcl/redo02.log

Log applied.

Media recovery complete.

Database altered.

SQL> alter database open resetlogs;

Database altered.

See Metalink Note 60545.1 for detailed examples.

Documents

General Backup and Recovery Questions