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Posts Tagged ‘backup’

Recovery Error: ORA-01207: file is more recent than control file – old control file

Posted by FatDBA on January 21, 2013

Solution steps when you started receiving ORA-01207.

Reason: The control file change sequence number in the data file is greater than the number in the control file. This implies that the wrong control file is being used. Note that repeatedly causing this error can make it stop happening without correcting the real problem. Every attempt to open the database will advance the control file change sequence number until it is great enough.

Scenario: In my scenario one of our SIT box lost all the copies of multiplexed ControlFiles from the system and after couple of minutes Database got crashed. While trying fixing the problem we discovered that we did’nt have the backup copies of Control Files Available, but we had a mount point backup available which holds all backup information but due to issues with our SMARTS (Monitoring Tool) backup script got failed to update the control file backup. So we didn’t knew that the ControlFile backup available was too old and have a very old sequence number registered.

So, after restoring the controlfile from that outdated backup we started recieving this error message during Databse OPEN:

SQL> alter database open;

ORA-00283: recovery session canceled due to errors
ORA-01122: database file 1 failed verification check
ORA-01110: data file 1: ‘/app/oracle/oradata/rac10g/system01.dbf’
ORA-01207: file is more recent than control file – old control file

Solution: recreate the control file.

1) dump controlfile to trace
SQL> alter database backup controlfile to trace as ‘/tmp/ccc.sql’;

2) startup database nomount
SQL> startup nomount

3) create the control file
SQL> @/tmp/ccc.sql
Control file created.

sys@SIT4435Z89> recover database using backup controlfile;

SQL> recover database using backup controlfile ;
ORA-00279: change 1904510 generated at 12/11/2012 15:46:23 needed for thread 1
ORA-00289: suggestion : +FRA
ORA-00280: change 1904510 for thread 1 is in sequence #62

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
+DATA/orcl/onlinelog/group_1.261.801074115
ORA-00310: archived log contains sequence 61; sequence 62 required
ORA-00334: archived log: ‘+DATA/orcl/onlinelog/group_1.261.801074115’

Now it is asking for Log sequence 62 which is not available under archive dest
ASMCMD> ls
thread_1_seq_52.314.801739289
thread_1_seq_53.294.801743225
thread_1_seq_54.295.801743259
thread_1_seq_55.285.801743403
thread_1_seq_56.283.801757235
thread_1_seq_57.282.801758303
thread_1_seq_58.281.801759635
thread_1_seq_59.286.801761231
thread_1_seq_60.305.801762327
thread_1_seq_61.296.801762385

We only have seq:61 available.

Hint: It could be still inside REDO Log groups and is not archived before the crash or Control file loss.
Hence we’ll check both of the two avialable redo groups to find seq:62
+DATA/orcl/onlinelog/group_1.261.801074115
+DATA/orcl/onlinelog/group_2.262.801074117

SQL> startup  mount
ORACLE instance started.

Total System Global Area 1636814848 bytes
Fixed Size                  2213856 bytes
Variable Size            1140852768 bytes
Database Buffers          486539264 bytes
Redo Buffers                7208960 bytes
Database mounted.
SQL> recover database using backup controlfile ;
ORA-00279: change 1904510 generated at 12/11/2012 15:46:23 needed for thread 1
ORA-00289: suggestion : +FRA
ORA-00280: change 1904510 for thread 1 is in sequence #62

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
+DATA/orcl/onlinelog/group_1.261.801074115
ORA-00310: archived log contains sequence 61; sequence 62 required
ORA-00334: archived log: ‘+DATA/orcl/onlinelog/group_1.261.801074115’

SQL> recover database using backup controlfile ;
ORA-00279: change 1904510 generated at 12/11/2012 15:46:23 needed for thread 1
ORA-00289: suggestion : +FRA
ORA-00280: change 1904510 for thread 1 is in sequence #62

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
+DATA/orcl/onlinelog/group_2.262.801074117
Log applied.
Media recovery complete.

Shows it was available under redo group: 2 (could be Current or Active) and it is successfully applied.

Finally we’d open DB in reset log mode.

SQL> alter database open resetlogs ;
Database altered.

Posted in Advanced | Tagged: , | Leave a Comment »

KEEP Clause * Error: ORA-19811: cannot have files in DB_RECOVERY_FILE_DEST with keep attributes*

Posted by FatDBA on January 13, 2013

KEEP option with RMAN:
If you have any backup criterion set and want to override settings then there is ‘KEEP FOREVER | UNTIL TIME’ clause from recovery manager which will help you to achieve required. There are certain conditions that’s needs to be fulfilled before using FOREVER clause.

Conditions:
1. You should be connected with the CATALOG server  (If using KEEP FOREVER Clause. No need if using KEEP UNTIL TIME Clause).
2. Oracle will not allow you to save backup pieces/set’s inside the FRA. You have to change the backup directory.

Let’s take an example:

[oracle@localhost ~]$ rman target / catalog rman/oracle90@orcl;
RMAN> backup current controlfile keep forever;

Starting backup at 13-JAN-13
current log archived

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_1: starting piece 1 at 13-JAN-13
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup command at 01/13/2013 18:35:23
ORA-19811: cannot have files in DB_RECOVERY_FILE_DEST with keep attributes

Solution:
RMAN> backup current controlfile keep forever format ‘/u01/%U’;

Starting backup at 13-JAN-13
current log archived

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_1: starting piece 1 at 13-JAN-13
channel ORA_DISK_1: finished piece 1 at 13-JAN-13
piece handle=/u01/20nvb5gk_1_1 tag=TAG20130113T183811 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 13-JAN-13
channel ORA_DISK_1: finished piece 1 at 13-JAN-13
piece handle=/u01/21nvb5gm_1_1 tag=TAG20130113T183811 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

current log archived
using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting archived log backup set
channel ORA_DISK_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=66 RECID=39 STAMP=804623897
channel ORA_DISK_1: starting piece 1 at 13-JAN-13
channel ORA_DISK_1: finished piece 1 at 13-JAN-13
piece handle=/u01/22nvb5gq_1_1 tag=TAG20130113T183811 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_1: starting piece 1 at 13-JAN-13
channel ORA_DISK_1: finished piece 1 at 13-JAN-13
piece handle=/u01/23nvb5gr_1_1 tag=TAG20130113T183811 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 13-JAN-13

Posted in Advanced | Tagged: , , | Leave a Comment »

Incrementally Updated Backup

Posted by FatDBA on January 1, 2013

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.

Posted in Advanced | Tagged: | Leave a Comment »

Hot Backup & Fractured Blocks: Test

Posted by FatDBA on December 26, 2012

Fractured block in Oracle
A block in which the header and footer are not consistent at a given SCN. In a user-managed backup, an operating system utility can back up a datafile at the same time that DBWR is updating the file. It is possible for the operating system utility to read a block in a half-updated state, so that the block that is copied to the backup media is updated in its first half, while the second half contains older data. In this case, the block is fractured.
For non-RMAN backups, the ALTER TABLESPACE … BEGIN BACKUP or ALTER DATABASE BEGIN BACKUP command is the solution for the fractured block problem. When a tablespace is in backup mode, and a change is made to a data block, the database logs a copy of the entire block image before the change so that the database can reconstruct this block if media recovery finds that this block was fractured.
The block that the operating system reads can be split, that is, the top of the block is written at one point in time while the bottom of the block is written at another point in time. If you restore a file containing a fractured block and Oracle reads the block, then the block is considered a corrupt.

Let’s perform a test:

–> Before ‘Begin Backup Mode’:

SQL> set autotrace trace stat
SQL> update etr set team=’Oracle’ where id=’7′;

1 row updated.
Statistics
———————————————————-
          0  recursive calls
          1  db block gets
          1  consistent gets
          0  physical reads
        300  redo size
        669  bytes sent via SQL*Net to client
        580  bytes received via SQL*Net from client
          4  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          1  rows processed

: It shows redo size=300 (Normal)

–> Let me put the tablespace in ‘Begin Backup’ Mode and try to executea DML again:
SQL> alter tablespace users begin backup;
Tablespace altered.

SQL> update etr set team=’Oracle’ where id=’1′;
1 row updated.
Statistics
———————————————————-
          1  recursive calls
          6  db block gets
          1  consistent gets
          0  physical reads
      17480  redo size
        669  bytes sent via SQL*Net to client
        580  bytes received via SQL*Net from client
          4  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          1  rows processed
: Check the size of Redo here (17480),  it’s actually the size of the datablock (+Normal redo) where the table column exits and a copy of the block is moved to the redo log buffer .

 
–> Let me try to execute the same DML statement again on same table
SQL> /

1 row updated.
Statistics
———————————————————-
          0  recursive calls
          1  db block gets
          1  consistent gets
          0  physical reads
        300  redo size
        669  bytes sent via SQL*Net to client
        580  bytes received via SQL*Net from client
          4  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          1  rows processed
: Now Redo size is again back to it’s original value (300).

Hence proved that rather pushing changed vectors/values in redo log buffer, oracle actually copies the entire block during initial operations (Reason of large REDO generation) and will not repeat the same for all subsequent operations on the same block.

ALTER TABLESPACE <> BEGIN BACKUP
is the solution to the Fractured Block problem which could have create inconsistencies in case of user managed backup’s which require OS commands to use.

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NOFILENAMECHECK Parameter: RMAN Backup’s

Posted by FatDBA on December 9, 2012

NOFILENAMECHECK (RMAN Parameter) is used to handle Data Block’s corruptions during Backup’s.

By default a checksum is calculated for every block read from a datafile and stored in the backup or image copy. If you use the NOCHECKSUM option, then checksums are not calculated. If the block already contains a checksum, however, then the checksum is validated and stored in the backup. If the validation fails, then the block is marked corrupt in the backup.

By default, the BACKUP command computes a checksum for each block and stores it in the backup. The BACKUP command ignores the values of DB_BLOCK_CHECKSUM because this initialization parameter applies to data files in the database, not backups. If you specify the NOCHECKSUM option, then RMAN does not perform a checksum of the blocks when writing the backup.

You cannot disable checksums for data files in the SYSTEM tablespace even if DB_BLOCK_CHECKSUM=false.

“To speed up the process of copying, you can use the NOCHECKSUM parameter. By default, RMAN computes a checksum for each block backed up, and stores it with the backup. When the backup is restored, the checksum is verified.”

Posted in Advanced | Tagged: , | 2 Comments »

Faster Incremental Backup’s: Enable Change Tracking (Block Change Tracking)

Posted by FatDBA on November 26, 2012

Prior to version 10g, however, incremental backups required a scan of an entire datafile to detect which blocks in it had changed. For very large databases, this made the time required for incrementals not much better than for full backups, even though space was saved.

Change Tracking, sometimes called Block Change Tracking, provides a solution by recording to a separate Change Tracking file which blocks have changed. The changes are written in real time by a background process CTWR (Change Tracking Writer).

The first level 0 incremental backup still requires a complete scan. Thereafter, the Change Tracking file is consulted during backups and the required blocks are accessed directly.

To create the Change Tracking file and enable Change Tracking, make sure the database is either open or mounted. Then issue an ALTER DATABASE command:

ALTER DATABASE
ENABLE BLOCK CHANGE TRACKING
USING FILE <pathname>;

where <pathname> is the operating system pathname to the location where you want the Change Tracking file to be stored. (If you have Oracle Managed Files enabled, the USING clause is optional, and the file will be created in the directory pointed to by DB_CREATE_FILE_DEST.)

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Oracle Secure Backup: Configuration

Posted by FatDBA on October 31, 2012

  • Steps to Configure Oracle Secure Backup (OSB):

Step 1. As the root user, check if the uncompress utility is installed on the system. If it is not,
create a symbolic link pointing to the gunzip utility:

(This is an important per-requisite and this is needed by the installed to uncompress files to installation directory and Mostly this does not comes pre-installed with Linux OS, create symbolic link with the Gunzip utility or install an RPM for this)
[root@lin32 ~]# uncompress
-bash: uncompress: command not found
[root@lin32 ~]# ln -s /bin/gunzip /bin/uncompress
Step 2. Create a directory for the download, and then issue the change directory command to
that directory:
[root@lin32 ~]# mkdir download
[root@lin32 ~]# cd download/
Step 3. Download OSB into the download directory and then unzip the product:
[root@lin32 download]# ls –l
total 43864
-rw-r–r– 1 root root 44866571 Jan 19 20:31 osb-10.3.0.1.0_linux32_release.zip
[root@lin32 download]# unzip osb-10.3.0.1.0_linux32_release.zip
Archive: osb-10.3.0.1.0_linux32_release.zip
creating: osb-10.3.0.1.0_linux32_cdrom090504/
extracting: osb-10.3.0.1.0_linux32_cdrom090504/OSB.10.3.0.1.0_LINUX32.rel
creating: osb-10.3.0.1.0_linux32_cdrom090504/doc/
creating: osb-10.3.0.1.0_linux32_cdrom090504/doc/dcommon/
creating: osb-10.3.0.1.0_linux32_cdrom090504/doc/dcommon/css/
inflating: osb-10.3.0.1.0_linux32_cdrom090504/doc/dcommon/css/blafdoc.css
inflating: osb-10.3.0.1.0_linux32_cdrom090504/doc/dcommon/css/bp_layout.css

inflating: osb-10.3.0.1.0_linux32_cdrom090504/welcome.html
inflating: osb-10.3.0.1.0_linux32_cdrom090504/doc.tar
Step 4. Create the directory where the install will place OSB files:
[root@lin32 download]# mkdir -p /usr/local/oracle/backup

Step 5. Issue the change directory command to the OSB destination and run setup:
[root@lin32 download]# cd /usr/local/oracle/backup/
[root@lin32 backup]# /root/download/osb-10.3.0.1.0_linux32_cdrom090504/setup
The following output is returned:
Welcome to Oracle’s setup program for Oracle Secure Backup. This program loads
Oracle Secure Backup software from the CD-ROM to a filesystem directory of your
choosing.
This CD-ROM contains Oracle Secure Backup version 10.3.0.1.0_LINUX32.
Please wait a moment while I learn about this host… done.
– – – – – – – – – – – – – – – – – – – – – – – – – – –
1. linux32
administrative server, media server, client
– – – – – – – – – – – – – – – – – – – – – – – – – – –
Loading Oracle Secure Backup installation tools… done.
Loading linux32 administrative server, media server, client… done.
– – – – – – – – – – – – – – – – – – – – – – – – – – –
Oracle Secure Backup has installed a new obparameters file.
Your previous version has been saved as install/obparameters.savedbysetup.
Any changes you have made to the previous version must be made to the new obparameters file.
Would you like the opportunity to edit the obparameters file
Please answer ‘yes’ or ‘no’ [no]:
Step 6. Leaving the default parameters for now, press ENTER to choose the default answer. The
following output is returned:
– – – – – – – – – – – – – – – – – – – – – – – – – – –
Loading of Oracle Secure Backup software from CD-ROM is complete.
You may unmount and remove the CD-ROM.
Would you like to continue Oracle Secure Backup installation with ‘installob’ now?
(The Oracle Secure Backup Installation Guide contains complete information about
installob.)
Please answer ‘yes’ or ‘no’ [yes]:
Step 7. Again, press ENTER to choose the default answer. The following output is returned:
– – – – – – – – – – – – – – – – – – – – – – – – – – –
Welcome to installob, Oracle Secure Backup’s installation program.
For most questions, a default answer appears enclosed in square brackets.
Press Enter to select this answer.
Please wait a few seconds while I learn about this machine… done.
Have you already reviewed and customized install/obparameters for your Oracle
Secure Backup installation [yes]?
Step 8. Again, press ENTER to choose the default answer and to leave the default parameters. The
following output is returned:
– – – – – – – – – – – – – – – – – – – – – – – – – – –
Oracle Secure Backup is not yet installed on this machine.
Oracle Secure Backup’s Web server has been loaded, but is not yet configured.
Choose from one of the following options. The option you choose defines the
software components to be installed.

Configuration of this host is required after installation completes.
You can install the software on this host in one of the following ways:
(a) administrative server, media server and client
(b) media server and client
(c) client
If you are not sure which option to choose, please refer to the Oracle Secure
Backup Installation Guide. (a,b or c) [a]?
Step 9. You are going to install all three components of OSB on the same server, so again press
ENTER to choose the default answer. The following output is returned:
Beginning the installation. This will take just a minute and will produce
several lines of informational output.
Installing Oracle Secure Backup on lin32 (Linux version 2.6.18-53.el5)
You must now enter a password for the Oracle Secure Backup encryption key store.
Oracle suggests you choose a password of at least 8 characters in length,
containing a mixture of alphabetic and numeric characters.
Please enter the key store password:
Re-type password for verification:
Step 10. Enter the OSB encryption key twice. The key is not displayed. You will see the
following output:
You must now enter a password for the Oracle Secure Backup ‘admin’ user. Oracle
suggests you choose a password of at least 8 characters in length, containing a
mixture of alphabetic and numeric characters.
Please enter the admin password:
Re-type password for verification:
Step 11. Enter the admin password twice. The password is not displayed. You will see the
following output:
You should now enter an email address for the Oracle Secure Backup ‘admin’ user.
Oracle Secure Backup uses this email address to send job summary reports and to
notify the user when a job requires input. If you leave this blank, you can set it
later using the obtool’s ‘chuser’ command.
Please enter the admin email address:
Step 12. Leave the e-mail address blank for now. The following output is returned:
generating links for admin installation with Web server
updating /etc/ld.so.conf
checking Oracle Secure Backup’s configuration file (/etc/obconfig)
setting Oracle Secure Backup directory to /usr/local/oracle/backup in /etc/obconfig
setting local database directory to /usr/etc/ob in /etc/obconfig
setting temp directory to /usr/tmp in /etc/obconfig
setting administrative directory to /usr/local/oracle/backup/admin in /etc/obconfig
protecting the Oracle Secure Backup directory
creating /etc/rc.d/init.d/observiced
activating observiced via chkconfig
initializing the administrative domain
****************************** N O T E ******************************
On Linux systems Oracle recommends that you answer no to the next two questions.
The preferred mode of operation on Linux systems is to use the /dev/sg devices for

attach points as described in the ‘ReadMe’ and in the ‘Installation and
Configuration Guide’.
Is lin32 connected to any tape libraries that you’d like to use with Oracle Secure Backup [no]?
Is lin32 connected to any tape drives that you’d like to use with Oracle Secure
Backup [no]?
Step 13. Since, in this example, you use a Linux system, answer “no,” as recommended by
Oracle, and configure the media server later. The following summary is returned:
Installation summary:
Installation Host OS Driver OS Move Reboot
Mode Name Name Installed? Required? Required?
admin lin32 Linux no no no
Oracle Secure Backup is now ready for your use.
The OSB administrative server, media server, and client are now installed. The OSB Web tool
is used to configure the tape library and tape drives.

Once configured launch your Web browser and supply the URL of the host running Oracle Secure Backup. Use the following syntax, where hostname can be a fully qualified domain name:

https://hostname
https://localhost.localdomain

Posted in Uncategorized | Tagged: | Leave a Comment »

Oracle Secure Backup ?

Posted by FatDBA on October 31, 2012

What is Oracle Secure backup ?
Oracle Secure Backup is centralized tape backup management software providing secure data protection for heterogeneous file systems and the Oracle Database. Oracle has its own media management software solution, Oracle Secure Backup (OSB). OSB is a fully integrated, RMAN-to-tape solution that does not require any third-party vendor software plug-in, and OSB has come a long way since its introduction in 10gR2.

In Oracle 10gR2 and Oracle 11g, you can utilize OSB to provide free backup to tape functionality, provided that you have a single tape head and it is attached directly to the server that contains the Oracle database that you want to back up. In addition to tape backup, OSB delivers an integrated Oracle database backup to third-party cloud (Internet) storage, through the Oracle Secure Backup Cloud Module. Oracle Secure Backup offers two tape management editions: OSB and OSB Express.

Oracle Secure Backup Interfaces:
You can interact with Oracle Secure Backup by means of the following tools:
– Oracle Secure Backup Web tool
– Oracle Secure Backup command-line interface
– Oracle Enterprise Manager

OSB Roles and Admin Domains:
Administrative server:
Each administrative domain must have exactly one administrative server. This server stores data pertinent to the operation of the administrative domain in a set of configuration files. Metadata relating to backup and restore operations is also stored on the administrative server in a backup catalog.
The administrative server runs the scheduler, which starts and monitors jobs within the administrative domain.

Media Server
A media server has one or more secondary storage devices, such as a library and tape drives, connected to it. At a minimum, a media server must have one standalone tape drive. Many media servers utilize robotic tape libraries.

Client
A client host is a host that has locally-accessed data that is backed up or restored by Oracle Secure Backup. Any host where Oracle Secure Backup is installed, or that contains data that Oracle Secure Backup accesses through Network Data Management Protocol (NDMP), can act as a client. Each client host is associated with one administrative server.

 

 

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Cumulative vs Differential vs Full Backups

Posted by FatDBA on October 27, 2012

Types of backups:

1. Full Backup or zero level backup.

2. Incremental Backup’s: Changed noted by the backup after a full backup. Broadly divided into two types

– Differential Incremental Backup (Figure a)

– Cumulative Incremental Backup (Figure b)

Level 0 and Level 1 Incremental Backups

Incremental backups can be either level 0 or level 1. A level 0 incremental backup, which is the base for subsequent incremental backups, copies all blocks containing data, backing the datafile up into a backup set just as a full backup would. The only difference between a level 0 incremental backup and a full backup is that a full backup is never included in an incremental strategy.

A level 1 incremental backup can be either of the following types:

  • A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
  • A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

Incremental backups are differential by default.

Differential Incremental Backups

In a differential level 1 backup, RMAN backs up all blocks that have changed since the most recent cumulative or differental incremental backup, whether at level 1 or level 0. RMAN determines which level 1 backup occurred most recently and backs up all blocks modified after that backup. If no level 1 is available, RMAN copies all blocks changed since the level 0 backup.

The following command performs a level 1 differential incremental backup of the database:

RMAN> BACKUP INCREMENTAL LEVEL 1 DATABASE;

If no level 0 backup is available, then the behavior depends upon the compatibility mode setting. If compatibility is >=10.0.0, RMAN copies all blocks changed since the file was created, and stores the results as a level 1 backup. In other words, the SCN at the time the incremental backup is taken is the file creation SCN. If compatibility <10.0.0, RMAN generates a level 0 backup of the file contents at the time of the backup, to be consistent with the behavior in previous releases.

Figure  Differential Incremental Backups (Default)

Description of Figure 4-1 follows

Cumulative Incremental Backups

In a cumulative level 1 backup, RMAN backs up all the blocks used since the most recent level 0 incremental backup. Cumulative incremental backups reduce the work needed for a restore by ensuring that you only need one incremental backup from any particular level. Cumulative backups require more space and time than differential backups, however, because they duplicate the work done by previous backups at the same level.

The following command performs a cumulative level 1 incremental backup of the database:

BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE; # blocks changed since level 0

Figure Cumulative Incremental Backups

Description of Figure 4-2 follows

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