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Backup and Restore
2012
Backup and Restore
2012
Contents
1
Archivelog mode ................................................................................................................................... 3
1.1
Display Archive information.......................................................................................................... 3
1.2
Configure Archive Log directory ................................................................................................... 3
1.3
Enabling Archivelog mode ............................................................................................................ 3
1.4
Disabling Archivelog mode............................................................................................................ 4
1.5
Enable Archivelog mode scenario ................................................................................................. 4
2
Configure RMAN environment for Backups.......................................................................................... 6
3
Database Backups ................................................................................................................................. 7
4
Display Backup Information ................................................................................................................ 10
4.1
List backupset.............................................................................................................................. 10
5
Restore ................................................................................................................................................ 11
6
Appendix ............................................................................................................................................. 14
6.1
RMAN Backup Retention Policies ............................................................................................... 14
6.2
Archived Redo Log Deletion Policies ........................................................................................... 14
6.3
Password Encryption of Backups ................................................................................................ 15
6.4
Consistent and Inconsistent Backups ......................................................................................... 15
Backup and Restore
2012
1 Archivelog mode
Archivelog mode is the mechanism that allows you to recover all committed transactions. This
mode protects your database from disk failure because your transaction information can be
restored and recovered from the archived redo log files. Archivelog mode ensures that after every
online redo log switch that the contents of the logs are successfully copied to archived redo log
files.
Database is required to be in archivelog mode for online backups.
1.1 Display Archive information
SQL> select log_mode from v$database;
LOG_MODE
-------------------NOARCHIVELOG
SQL> archive log list;
Database log mode
Automatic archival
Archive destination
Oldest online log sequence
Current log sequence
No Archive Mode
Disabled
/data14/oracle_data/orcl/archived_log_1
7185
7186
1.2 Configure Archive Log directory
alter system set DB_RECOVERY_FILE_DEST='' ;
ALTER SYSTEM SET log_archive_dest =
'/data14/oracle_data/orcl/archived_log_1' SCOPE=BOTH;
1.3 Enabling Archivelog mode
To place your database in archivelog mode, perform the following steps:
a.
b.
c.
d.
Connect as sysdba.
Shut down your database.
Start up in mount mode.
Alter the database into archivelog mode.
Backup and Restore
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e. Open your database for use.
1.4 Disabling Archivelog mode
If you want to disable archivelog mode, then you would execute all the previous steps, with one
change; in step 4, you will need to use the noarchivelog parameter (instead of archivelog mode).
1.5 Enable Archivelog mode scenario
a. Check database mode
SQL> select name, log_mode
from v$database;
NAME
LOG_MODE
--------- -----------ORCL
NOARCHIVELOG
b. If database is in no archivelog mode then configure archivelog directory.
alter system set DB_RECOVERY_FILE_DEST='' ;
ALTER SYSTEM SET log_archive_dest =
'/data14/oracle_data/orcl/archived_log_1'
SCOPE=BOTH;
c. Check the archive destination parameter to confirm the archivelog destination path.
SQL> archive log list;
Database log mode
No Archive Mode
Automatic archival
Disabled
Archive destination
/data14/oracle_data/orcl/archived_log_1
Oldest online log sequence
7185
Current log sequence
7186
d. Execute the following commands in sequence to enable the archivelog mode.
SQL>Shutdown immediate;
SQL> startup mount;
Backup and Restore
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ORACLE instance started.
Total System Global Area 1.3495E+10 bytes
Fixed Size
2218032 bytes
Variable Size
7784630224 bytes
Database Buffers
5637144576 bytes
Redo Buffers
71471104 bytes
Database mounted.
SQL> alter database archivelog;
Database altered.
SQL> alter database open;
Database altered.
e. Verify database mode
SQL> archive log list;
Database log mode
Automatic archival
Archive destination
Oldest online log sequence
Next log sequence to archive
Current log sequence
Archive Mode
Enabled
/data14/oracle_data/orcl/archived_log_1
7185
7186
7186
SQL> select name, log_mode
from v$database;
NAME
LOG_MODE
--------- -----------ORCL
ARCHIVELOG
f.
In case if the following error occurs during configuration of archivelog directory then
execute the following command “alter system set DB_RECOVERY_FILE_DEST=''
;”
SQL> ALTER SYSTEM SET log_archive_dest =
"location=/data14/oracle_data/orcl/archived_log_1" SCOPE=BOTH
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16018: cannot use LOG_ARCHIVE_DEST with LOG_ARCHIVE_DEST_n or
DB_RECOVERY_FILE_DEST
Backup and Restore
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2 Configure RMAN environment for Backups
The below table has details of commands that are executed before RMAN backup and restore
command.
Sr.
Command
Purpose
No.
CONFIGURE RETENTION POLICY TO
1.
We have disabled the retention policy.
NONE;
Please refer section#5.1 for more details.
2.
CONFIGURE ARCHIVELOG DELETION
POLICY BACKED UP 2 TIMES TO
DEVICE TYPE DISK;
We have kept two backups of archivelog files.
Please refer section#5.1 for more details.
3.
CONFIGURE CONTROLFILE AUTOBACKUP
ON;
Configure RMAN to back up the control file
after each backup
4.
CONFIGURE CONTROLFILE AUTOBACKUP
FORMAT FOR DEVICE TYPE DISK TO
'e:\rman_backup\cf%F';
Locating for storing control file backup with
unique filename.
By default, the format of the autobackup file
for all configured devices is the substitution
variable %F. This variable format translates
into c-IIIIIIIIII-YYYYMMDD-QQ, where:
 IIIIIIIIII stands for the DBID.
 YYYYMMDD is a time stamp of the
day the backup is generated
 QQ is the hex sequence that starts
with 00 and has a maximum of FF
5.
SET ENCRYPTION ON IDENTIFIED BY
"test" ONLY;
SET DECRYPTION IDENTIFIED BY
"test";
This command will encrypt the database
backup by using default encryption algorithm
128-bit Advanced Encryption Standard (AES).
The backup will be password protected and
to restore the backup we need to use the
step mentioned in point#6 of this table.
6.
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3 Database Backups
There are following types of backup that we create using RMAN.
Sr.
No.
1.
2.
3.
Database
Mode
Offline
Online
Online
Backup Type
Description
Full
An offline full backup of a database will contain complete
backups of all the datafiles, also called a cold backup, is
one made after shutting down the database using the
shutdown command or the shutdown command with the
immediate or transactional clause. An offline backup,
provided you make one after the database is shut down
gracefully, is always consistent, whether you're operating
in archivelog or noarchivelog mode. When making an
offline backup with RMAN, you must, however, start the
database you want to back up in the mount mode.
An online full backup of a database will contain complete
backups of all the datafiles. The online backup is made
while the database instance is still open. By definition, an
online backup is always inconsistent. During a recovery,
the application of the necessary archived redo logs will
make the backup consistent. Thus, you can make online
backups of any database you're operating, and the
resulting inconsistent backups can be made consistent
with the application of archived redo logs. However, for
databases running in noarchivelog mode, open
inconsistent backups aren't recommended.
This backup is same as online full backup. The difference
between a full backup and a level backup is that a full
backup is not known to any subsequent incremental
backups. Therefore, they cannot be used as a basis when
Full
Incremental
Level 0
Script
full_off_backup.sql
full_on_backup.sql
incr_on_level_0_backup.sql
Backup and Restore
4.
5.
Online
Online
Incremental
differential
Level 1
Incremental
cumulative
level 1
2012
applying incremental backups during a recovery
operation.
Backs up only blocks that have been modified since the
previous backup. A differential level 1 backup backs up all
blocks that have been modified since the last level 0 or
level 1 backup.
A cumulative level 1 backup backs up all blocks that have
changed since the last level 0 backup.
incr_on_level_1_backup.sql
We will be configuring Incremental level 0 and incremental differential level 1 backup. The order of the backup would be as follows:
a. Incremental level 0
b. Multiple level 1 backups (as per schedule)
Example: In a week there can be one level 0 and multiple level 1 backups.
Backup incremental level 0 database plus archivelog delete input;
select a.set_count, a.start_time, a.completion_time, sum(b.blocks)
from v$backup_set a, v$backup_datafile b
where a.set_count=b.set_count
and to_char(a.start_time, 'mm/dd/yyyy hh24:mi:ss')=
(select to_char(max(start_time), 'mm/dd/yyyy hh24:mi:ss')
from v$backup_set
where incremental_level=1)
group by a.set_count, a.start_time, a.completion_time ;
Backup and Restore
RMAN incremental backup
Backup incremental level 1 database plus archivelog delete input;
2012
Backup and Restore
4 Display Backup Information
4.1 List backupset
Crosscheck backup;
run {
}
Crosscheck archivelog all;
DELETE EXPIRED ARCHIVELOG all;
delete backup tag='INC_DAILY_DB_BACKUP';
2012
Backup and Restore
5 Restore
Deleted all files only oracle home is set
RMAN prompt
===============
RMAN> startup nomount;
startup failed: ORA-01078: failure in processing system parameters
LRM-00109: could not open parameter file
'/data2/oracle/app/oracle/product/11.2.0/dbhome_1/dbs/initorcl.ora'
starting Oracle instance without parameter file for retrieval of spfile
Oracle instance started
Total System Global Area
Fixed Size
Variable Size
Database Buffers
Redo Buffers
158662656 bytes
2211448 bytes
92275080 bytes
58720256 bytes
5455872 bytes
===============
Identify DBID
Start database
RMAN> startup nomount;
startup failed: ORA-01078: failure in processing system parameters
LRM-00109: could not open parameter file
'/data2/oracle/app/oracle/product/11.2.0/dbhome_1/dbs/initorcl.ora'
starting Oracle instance without parameter file for retrieval of spfile
Oracle instance started
Total System Global Area
Fixed Size
Variable Size
Database Buffers
158662656 bytes
2211448 bytes
92275080 bytes
58720256 bytes
2012
Backup and Restore
Redo Buffers
2012
5455872 bytes
Restore spfile
SET DECRYPTION IDENTIFIED BY "test";
RESTORE SPFILE TO '/tmp/spfileTEMP.ora' FROM
'/data15/oracle_data/orcl/rman_backup/FULL_DB_cfc-1290647802-20121025-08' ;
Create pfile
Create /tmp/initTemp.ora file with following contents
Spfile = /tmp/spfileTEMP.ora
RMAN> startup force pfile=/tmp/initTemp.ora nomount
RMAN> startup force pfile=/tmp/initTemp.ora nomount
Oracle instance started
Total System Global Area 13495463936 bytes
Fixed Size
Variable Size
Database Buffers
Redo Buffers
2218032 bytes
7784630224 bytes
5637144576 bytes
71471104 bytes
Restore control file
SET DECRYPTION IDENTIFIED BY "test";
SET DBID 1290647802;
RUN
{
SET CONTROLFILE AUTOBACKUP FORMAT
FOR DEVICE TYPE DISK TO '/data15/oracle_data/orcl/rman_backup/FULL_DB_cf%F';
RESTORE CONTROLFILE FROM '/data15/oracle_data/orcl/rman_backup/FULL_DB_cfc1290647802-20121025-07' ;
}
executing command: SET CONTROLFILE AUTOBACKUP FORMAT
Starting restore at 25-OCT-12
allocated channel: ORA_DISK_1
Backup and Restore
channel ORA_DISK_1: SID=391 device type=DISK
channel ORA_DISK_1: restoring control file
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
output file name=/data13/oracle_data/orcl/control_file_1/control01.ctl
output file name=/data16/oracle_data/orcl/control_file_2/control02.ctl
Finished restore at 25-OCT-12
Restore database
RMAN> Shutdown immediate;
RMAN> Startup pfile=/tmp/initTemp.ora mount;
connected to target database (not started)
Oracle instance started
database mounted
Total System Global Area 13495463936 bytes
Fixed Size
Variable Size
Database Buffers
Redo Buffers
2218032 bytes
7784630224 bytes
5637144576 bytes
71471104 bytes
Errors
ORA-01113: file 1 needs media recovery
ORA-19914: unable to encrypt backup
ORA-28365: wallet is not open
SQL>
RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL
REPORT SCHEMA;
2012
Backup and Restore
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6 Appendix
6.1 RMAN Backup Retention Policies
A user-defined policy for determining how long backups and archived logs need to be retained for
media recovery. There are following types of retention policies.
a. Recovery window
The RECOVERY WINDOW parameter of the CONFIGURE command specifies the number
of days between the current time and the earliest point of recoverability. RMAN does not
consider any full or level 0 incremental backup as obsolete if it falls within the recovery
window. Additionally, RMAN retains all archived logs and level 1 incremental backups that
are needed to recover to a random point within the window.
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;
b. Redundancy
The REDUNDANCY parameter of the CONFIGURE RETENTION POLICY command specifies
how many full or level 0 backups of each datafile and control file that RMAN should keep.
CONFIGURE RETENTION POLICY TO REDUNDANCY 3;
c. Disabling the Retention Policy
When you disable the retention policy, RMAN does not consider any backup as obsolete.
To disable the retention policy, run this command:
CONFIGURE RETENTION POLICY TO NONE;
6.2 Archived Redo Log Deletion Policies
Archived redo logs can be deleted automatically by the database or as a result of user-initiated
RMAN commands.
a. Enabling Archive Log Deletion policy
The following command will enable the archivelog deletion policy.
CONFIGURE ARCHIVELOG DELETION POLICY BACKED UP integer TIMES TO DEVICE
TYPE DISK
If integer backups of the logs exist, then the BACKUP ARCHIVELOG command skips the
logs.
b. Disabling Archive Log deletion policy
The following command will enable the archivelog deletion policy.
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE;
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6.3 Password Encryption of Backups
Password encryption requires that the DBA provide a password when creating and restoring
encrypted backups. Restoring a password-encrypted backup requires the same password used to
create the backup.
Password encryption is useful for backups that will be restored at remote locations, but which
must remain secure in transit. Password encryption cannot be persistently configured. You do not
need to configure an Oracle wallet if password encryption will be used exclusively.
Caution:
If you forget or lose the password that you used to encrypt a password-encrypted backup, then
you will be unable to restore the backup.
To use password encryption, use the SET ENCRYPTION ON IDENTIFIED BY password ONLY
command in your RMAN scripts.
6.4 Consistent and Inconsistent Backups
To understand the crucial difference between consistent and inconsistent backups, you must first
understand the concept of the system change number (SCN). The SCN is an Oracle server-assigned
number that indicates a committed version of the database. It's quite possible that different
datafiles in the database might have a different SCN at any given point in time. If the SCNs across
all the datafiles are synchronized, it means that the data across the datafiles comes from a single
point of time and, thus, is consistent.
During each checkpoint, the server makes all database file SCNs consistent with respect to an
identical SCN. In addition, it updates the control file with that SCN information. This
synchronization of the SCNs gives you a consistent backup of your database. Not only does each
of the datafiles in the database have the same SCN, it must also not contain any database changes
beyond that common SCN.
If you back up your database while it's running, you may end up with backups of the various
datafiles at various time points and different SCNs. This means your backups are inconsistent,
since the SCNs aren't identical across all the datafiles.