Oracle Backup and Recovery Scenarios

Some standard recovery scenarios

Deleted or Corrupted Datafile

If a database datafile in the $ORACLE_HOME/oradata/XE  is deleted then the database will no longer open.  It is not possible to recover just the datafile from a backup since it will be out of sync with the other datafiles and data will have been lost.  If the database has been setup in archivelog mode and backuped as described in Oracle XE Backup then the database can be recovered to the most recent archive log.

Backup

Run a backup on the database as oracle:

[oracle@localhost ~]$ $ORACLE_HOME/config/scripts/backup.sh 
Doing online backup of the database.
Backup of the database succeeded.
Log file is at /usr/lib/oracle/xe/oxe_backup_current.log.
Press ENTER key to exit
[oracle@localhost ~]$

Check the database is running and query the datafiles:

[oracle@localhost ~]$ sqlplus system

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 09:26:04 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Enter password: 

Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production

SQL> select substr(file_name,1,50) "File", bytes/(1024*1024) "Size (MB)" from dba_data_files;

File                                                Size (MB)
-------------------------------------------------- ----------
/usr/lib/oracle/xe/oradata/XE/users.dbf                   100
/usr/lib/oracle/xe/oradata/XE/sysaux.dbf                  220
/usr/lib/oracle/xe/oradata/XE/undo.dbf                    210
/usr/lib/oracle/xe/oradata/XE/system.dbf                  340

SQL>

Corrupt

Delete the users.dbf datafile and create a new empty file:

[oracle@localhost ~]$ cd oradata/XE
[oracle@localhost XE]$ ls -al
total 898824
drwxr-x--- 2 oracle dba      4096 May 26 11:21 .
drwxr-xr-x 3 oracle dba      4096 May 25 21:43 ..
-rw-r----- 1 oracle dba   7061504 May 26 11:23 control.dbf
-rw-r----- 1 oracle dba 230694912 May 26 11:21 sysaux.dbf
-rw-r----- 1 oracle dba 356524032 May 26 11:21 system.dbf
-rw-r----- 1 oracle dba  20979712 May 26 11:21 temp.dbf
-rw-r----- 1 oracle dba 220209152 May 26 11:21 undo.dbf
-rw-r--r-- 1 oracle dba 104865792 May 26 11:21 users.dbf
[oracle@localhost XE]$ rm users.dbf
[oracle@localhost XE]$ touch users.dbf
[oracle@localhost XE]$ ls -al
total 796312
drwxr-x--- 2 oracle dba      4096 May 26 11:23 .
drwxr-xr-x 3 oracle dba      4096 May 25 21:43 ..
-rw-r----- 1 oracle dba   7061504 May 26 11:23 control.dbf
-rw-r----- 1 oracle dba 230694912 May 26 11:21 sysaux.dbf
-rw-r----- 1 oracle dba 356524032 May 26 11:21 system.dbf
-rw-r----- 1 oracle dba  20979712 May 26 11:21 temp.dbf
-rw-r----- 1 oracle dba 220209152 May 26 11:21 undo.dbf
-rw-r--r-- 1 oracle dba         0 May 26 11:23 users.dbf
[oracle@localhost XE]$

Shutdown the database:

[oracle@localhost ~]$ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 11:26:37 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> connect / as sysdba
Connected.
SQL> shutdown immediate
ORA-01110: data file 4: '/usr/lib/oracle/xe/oradata/XE/users.dbf'
ORA-01115: IO error reading block from file 4 (block # 1)
ORA-27072: File I/O error
Additional information: 4
Additional information: 1
SQL>

The database is now corrupted and can not be restarted.

Restore

Run the restore.sh script

[oracle@localhost ~]$ $ORACLE_HOME/config/scripts/restore.sh
This operation will shut down and restore the database. Are you sure [Y/N]?Y
Restore in progress...
Restore of the database succeeded.
Log file is at /usr/lib/oracle/xe/oxe_restore.log.
Press ENTER key to exit
[oracle@localhost ~]$

Verify

Check that the users.dbf file is restored

[oracle@localhost ~]$ $ORACLE_HOME/config/scripts/restore.sh
This operation will shut down and restore the database. Are you sure [Y/N]?Y
Restore in progress...
Restore of the database succeeded.
Log file is at /usr/lib/oracle/xe/oxe_restore.log.
Press ENTER key to exit
[oracle@localhost ~]$ cd oradata/XE
[oracle@localhost XE]$ ls -al
total 898824
drwxr-x--- 2 oracle dba      4096 May 26 11:31 .
drwxr-xr-x 3 oracle dba      4096 May 25 21:43 ..
-rw-r----- 1 oracle dba   7061504 May 26 11:35 control.dbf
-rw-r----- 1 oracle dba 230694912 May 26 11:31 sysaux.dbf
-rw-r----- 1 oracle dba 356524032 May 26 11:31 system.dbf
-rw-r----- 1 oracle dba  20979712 May 26 11:31 temp.dbf
-rw-r----- 1 oracle dba 220209152 May 26 11:31 undo.dbf
-rw-r--r-- 1 oracle dba 104865792 May 26 11:31 users.dbf
[oracle@localhost XE]$

Verify that the database knows about the users.dbf datafile again:

[oracle@localhost ~]$ sqlplus system

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 09:50:28 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Enter password: 

Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
 
SQL> select substr(file_name,1,50) "File", bytes/(1024*1024) "Size (MB)" from dba_data_files;


File                                                Size (MB)
-------------------------------------------------- ----------
/usr/lib/oracle/xe/oradata/XE/users.dbf                   100
/usr/lib/oracle/xe/oradata/XE/sysaux.dbf                  220
/usr/lib/oracle/xe/oradata/XE/undo.dbf                    210
/usr/lib/oracle/xe/oradata/XE/system.dbf                  340

SQL>

Restart the database just to make sure:

[oracle@localhost ~]$ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 11:37:12 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> connect / as sysdba
Connected.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  289406976 bytes
Fixed Size                  1258488 bytes
Variable Size              92277768 bytes
Database Buffers          192937984 bytes
Redo Buffers                2932736 bytes
Database mounted.
Database opened.
SQL>

Lost Database Server

This is a more sever loss of data when the database server goes down and can not be restarted.  The best solution is to create a new database server and restore the backups to the new database.  This solution assumes that the database was in archivelog mode, see Oracle XE Backup, and being backed up to an external system on a daily basis.

Install Oracle XE

Install Oracle XE on the new database server as root:

[root@localhost oracle]# rpm -ivh oracle-xe-10.2.0.1-1.0.i386.rpm 
Preparing...                ########################################### [100%]
   1:oracle-xe              ########################################### [100%]
Executing Post-install steps...

You must run '/etc/init.d/oracle-xe configure' as the root user to 
configure the database.

[root@localhost oracle]#

Configure the database, accept all the defaults and set the system password:

[root@localhost oracle]# /etc/init.d/oracle-xe configure

Oracle Database 10g Express Edition Configuration
-------------------------------------------------
This will configure on-boot properties of Oracle Database 10g Express 
Edition.  The following questions will determine whether the database should 
be starting upon system boot, the ports it will use, and the passwords that 
will be used for database accounts.  Press <Enter> to accept the defaults. 
Ctrl-C will abort.

Specify the HTTP port that will be used for Oracle Application Express [8080]:

Specify a port that will be used for the database listener [1521]:

Specify a password to be used for database accounts.  Note that the same
password will be used for SYS and SYSTEM.  Oracle recommends the use of 
different passwords for each database account.  This can be done after 
initial configuration:
Confirm the password:

Do you want Oracle Database 10g Express Edition to be started on boot (y/n) [y]:

Starting Oracle Net Listener...Done
Configuring Database...Done
Starting Oracle Database 10g Express Edition Instance...Done
Installation Completed Successfully.
To access the Database Home Page go to "http://127.0.0.1:8080/apex"
[root@localhost oracle]#

Configure the Database

As oracle set the database to be archivelog mode

[oracle@localhost ~]$ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 12:06:31 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> connect / as sysdba
Connected.
SQL> shutdown
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.

Total System Global Area  289406976 bytes
Fixed Size                  1258488 bytes
Variable Size              92277768 bytes
Database Buffers          192937984 bytes
Redo Buffers                2932736 bytes
Database mounted.
SQL> alter database archivelog;

Database altered.

SQL> alter database open;

Database altered.

SQL>

Shutdown the database

[oracle@localhost ~]$ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 14:21:43 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> connect / as sysdba
Connected.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>

Restore Files from Backup

Restore the:

  • app/oracle/flash_recovery_area/XE/archivelog/
  • app/oracle/flash_recovery_area/XE/autobackup/
  • app/oracle/flash_recovery_area/XE/backupset/
  • app/oracle/flash_recovery_area/XE/onlinelog/

directories from backups.  Make sure that the oracle user owns all the restored files.

Restore the Database

Restore the database using the restore.sh script and enter the location of the restored files (/usr/lib/oracle/xe/app/oracle/flash_recovery_area/).

[oracle@localhost ~]$ $ORACLE_HOME/config/scripts/restore.sh
This operation will shut down and restore the database. Are you sure [Y/N]?Y
Restore in progress...
Enter the flash recovery area location:/usr/lib/oracle/xe/app/oracle/flash_recovery_area
Restore of the database succeeded.
Log file is at /usr/lib/oracle/xe/oxe_restore.log.
Press ENTER key to exit
[oracle@localhost ~]$

Verify

Log into the database as a user:

[oracle@localhost ~]$ sqlplus em

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 26 14:34:58 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Enter password: 

Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production

SQL>

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