Backups And Recovery

15
Copyright © 2009, Oracle. All rights reserved.
Performing Database Backups
Prepared by Asif Malik
contact no: 03106321039

Copyright © 2009, Oracle. All rights reserved.15 - 2
Objectives
After completing this lesson, you should be able to:
• Create consistent database backups
• Back up your database without shutting it down
• Create incremental backups
• Automate database backups
• Manage backups and view backup reports

Backup Solutions: Overview
Backups can be performed by using:
• Recovery Manager
• Oracle Secure Backup
• User-managed backup
Image copies
Backup pieces
Backup data
Data files
Fast recovery area
Target
database
Redundant
archive log
files
Archive
log files

Backup Solutions: Overview
• As you will see in the remainder of this lesson, Recovery
Manager (RMAN) is the recommended method of backing
up your Oracle database.
• Oracle Secure Backup complements existing functionality
by adding backup to tape and backup of operating system
files.
• User-managed backups are based on scripts that a DBA
must write. This option is being phased out because it is
more labor intensive.

Oracle Secure Backup
• Oracle Secure Backup and RMAN provide an
end-to-end backup solution for Oracle environments:
– Centralized tape backup management for file system data
and the Oracle database
– Most well-integrated media management layer for RMAN
backups
– Backup of any data anywhere on the network
• A single technical support resource for the entire backup
solution expedites problem resolution.
• This ensures reliable data protection at lower cost and
complexity.

Oracle Secure Backup
• Oracle’s current backup and recovery product for the database is Recovery
Manager. Oracle Secure Backup complements existing functionality in the
following ways:
– Complete backup solution: Oracle Secure Backup provides data
protection for the database and nondatabase data to protect the entire
Oracle environment.
– Media management: Oracle Secure Backup provides the media
management layer for RMAN database backups to tape. Before Oracle
Secure Backup, customers had to purchase expensive third-party media
management products offering integration with RMAN tape backups.
– Backup anywhere on the network: Oracle Secure Backup backs up data
from multiple network-attached computer systems to tertiary storage
resources on the network. Oracle Secure Backup supports diverse
configurations of servers, clients, Network Attached Storage (NAS) servers,
and tertiary storage devices and protects network storage environments.
• The combination of RMAN and Oracle Secure Backup provides an end-to-end
backup solution that is entirely within the Oracle product stack. This solution
makes better customer support possible because Oracle Corporation is
responsible for the entire backup solution.

User-Managed Backup
A user-managed scenario:
• Is a manual process of tracking backup needs and status
• Typically uses your own written scripts
• Requires that database files be put in the correct mode for
backup
• Relies on operating system commands to make backups
of files

User-Managed Backup
• A user-managed backup can be performed interactively.
However, most often it entails the writing of scripts to
perform the backup. There are several scenarios that can
be run, and scripts must be written to handle them.
• Some of the actions that scripts must take:
– Querying V$DATAFILE to determine the data files that need
to be backed up and their current state
– Querying V$LOGFILE to identify the online redo log files
– Querying V$CONTROLFILE to identify the control file to back
up
– Placing each tablespace in online backup mode
– Querying V$BACKUP to see what data files are part of a
tablespace that has been placed in online backup mode
– Issuing operating system copy commands to copy the data
files to the backup location
– Bringing each tablespace out of online backup mode

Terminology
• Backup strategy may include:
– Entire database (whole)
– Portion of the database (partial)
• Backup type may indicate inclusion of:
– All data blocks within your chosen files (full)
– Only information that has changed since a previous backup
(incremental)
—
Cumulative (changes since last level 0)
—
Differential (changes since last incremental)
• Backup mode may be:
– Offline (consistent, cold)
– Online (inconsistent, hot)
DatabaseData files
Online
redo log
files
Control
files

Terminology
Whole database backup: Includes all data files and at least one control file
(Remember that all control files in a database are identical.)
• Partial database backup: May include zero or more tablespaces and
zero or more data files; may or may not include a control file
• Full backup: Makes a copy of each data block that contains data and
that is within the files being backed up
• Incremental backup: Makes a copy of all data blocks that have
changed since a previous backup. The Oracle database supports two
levels of incremental backup (0 and 1). A level 1 incremental backup
can be one of two types: cumulative or differential. A cumulative backup
backs up all changes since the last level 0 backup. A differential backup
backs up all changes since the last incremental backup (which could be
either a level 0 or level 1 backup).
• Offline backups (also known as “cold” or consistent backup): Are taken
while the database is not open. They are consistent because, at the time
of the backup,
• Online backups (also known as “hot” or inconsistent backup): Are
taken while the database is open. They are inconsistent because, with
the database open, there is no guarantee that the data files are
synchronized with the control files.

Terminology
Backups may be stored as:
• Image copies
• Backup sets
Data file #2
Data file #3
Data file #4
Data file #5
Data file #1
Data file #6
Image copies
(Duplicate data and log files in OS format)
Backup set
(Binary, compressed files in
Oracle proprietary format)
Data file #1 Data file #2

Terminology (continued)
• Image copies: Are duplicates of data or archived log files (similar to simply
copying the files by using operating system commands)
• Backup sets: Are collections of one or more binary files that contain one or more
data files, control files, server parameter files, or archived log files. With backup
sets, empty data blocks are not stored, thereby causing backup sets to use less
space on the disk or tape. Backup sets can be compressed to further reduce the
space requirements of the backup.
• Image copies must be backed up to the disk. Backup sets can be sent to the disk
or directly to the tape.
• The advantage of creating a backup as an image copy is improved granularity of
the restore operation. With an image copy, only the file or files need to be
retrieved from your backup location. With backup sets, the entire backup set
must be retrieved from your backup location before you extract the file or files
that are needed.
• The advantage of creating backups as backup sets is better space usage. In
most databases, 20% or more of the data blocks are empty blocks. Image copies
back up every data block, even if the data block is empty. Backup sets
significantly reduce the space required by the backup. In most systems, the
advantages of backup sets outweigh the advantages of image copies.
• mode is a mode that you can put the database in for creating a backup of all
transactions that have occurred in the database so that you can recover to any
point in time.

Recovery Manager (RMAN)
• Powerful control and scripting language
• Integrated with Enterprise Manager
• Published API that enables interface with most popular
backup software
• Backing up data, control, archived log, and server
parameter files
• Backing up files to the disk or tape

Recovery Manager (RMAN)
• RMAN is the component of the Oracle database that is
used to perform backup and recovery operations. It can
make consistent and inconsistent backups, perform
incremental and full backups, and back up either the whole
database or a portion of it.
• RMAN uses its own powerful job control and scripting
language, as well as a published API that interfaces RMAN
with many popular backup software solutions.
• RMAN can store backups on the disk for quick recovery or
place them on the tape for long-term storage. For RMAN to
store backups on the tape, you must either use Oracle
Secure Backup.
• Enterprise Manager supplies a graphical interface to the
most commonly used RMAN functionality

Configuring Backup Settings

• Select Enterprise Manager > Availability > Backup Settings. Here you
can manage the persistent backup settings that are used for creating
backups. There are separate settings for the disk and the tape. Tape
settings depend on the media management library capabilities. Disk
settings include:
– Parallelism: How many separate streams of backup information do
you want to create? The best setting for parallelism depends on
your hardware. As hardware resources increase, the appropriate
degree of parallelism also increases. Generally, you want to set
your parallelism to the number of disks that your disk backup
location is striped over. For tape backup, you want to set your
parallelism to the same number of tape drives that you have.
– Disk backup location: Where should backups be stored? The
default is the fast recovery area. If you change this, click Test Disk
Backup to verify that RMAN can write to the new location.
– Disk backup type: Select Backup Set, Compressed Backup Set, or
Image Copy.
• Click the Backup Set tab to set the maximum file size of backup pieces,
specify the compression algorithm to be used for compressed backup
sets, and specify redundancy for tape backups. Host credentials are
required for Enterprise Manager to save changes to the backup settings.

Change
tracking
fileData files
Backup
pieces
Recovery
area
Best practice

Configuring Backup Settings (continued)
• Click the Policy tab to:
– Automatically back up the control file and server parameter file (SPFILE)
with each backup. You can also specify a location for these backups if you
do not want them to go to the fast recovery area.
– Optimize backups by not backing up files that exactly match a file that is
already part of the retained backups. This setting enables you to skip
read-only and offline data files.
– Enable block change tracking and specify a location for the tracking file. If
you intend to create incremental backups, this setting can decrease the
time required to choose which blocks to include in the incremental
backup.
– Exclude tablespaces from a whole database backup. Some administrators
choose not to back up tablespaces containing data or objects that can be
easily re-created (such as indexes or data that is batch-loaded frequently).
– Specify a retention policy: How long should RMAN keep your backups? If
you are using the fast recovery area to store backups, RMAN
automatically deletes old backups to make room for new ones (if the
retention policy allows it). By default, only the last backup is retained. The
retention policy can be specified as a number of backups or a number of
days.

Scheduling Backups: Strategy

Scheduling Backups: Strategy
• Select Enterprise Manager > Availability > Schedule Backup. Select
either the Oracle-Suggested Backup strategy or your own
customized strategy. The Oracle-Suggested Backup strategy makes
a one-time whole-database backup, which is performed online. This
is a baseline incremental level 0 backup. The automated backup
strategy then schedules incremental level 1 backups for each
successive day. For day 3 and onward, RMAN applies the level 1
backup from the beginning of day n-1 to the level 0 backup before
beginning the incremental backup for that day.
• By clicking Schedule Customized Backup, you gain access to a
wider range of configuration options. Select the objects that you
want to back up—the whole database (the default) or individual
tablespaces, data files, archived logs, or any Oracle backups
currently residing on the disk (to move them to the tape).
• Both strategies enable you to set up encrypted backups.

Scheduling Backups: Options

Scheduling Backups: Options
• Select full or incremental backup type. If you are performing a full
database backup, you can select “Use as the base of an incremental
backup strategy” to make the full database backup an incremental
level 0 backup. If you are using image copies, you can select
“Refresh the latest datafile copy on disk to the current time using the
incremental backup” to update the existing backup rather than create
a new image copy.
• Select Online Backup if you want to perform this task while users are
continuing to use the database. If users do not need access, select
“Offline Backup,” which is performed with a mounted instance.
• Select “Delete obsolete backups” to remove any backups that fall
outside the retention policy that you configured earlier. RMAN
automatically removes obsolete backups if you are backing up to the
fast recovery area. Details about the advanced options and
encryption are discussed in the course titled Oracle Database 11g:
Administration Workshop II and in the backup and recovery
documentation.

Scheduling Backups: Settings

Scheduling Backups: Schedule

Scheduling Backups: Review

Scheduling Backups
: Settings
Select whether the backup is to go to the disk or to the tape.
To create a one-time backup (in addition to your regularly scheduled
backups), click Override Current Settings and specify your backup
settings.
Schedule
• Choose how you want the backup to be scheduled—either as a
one-time job or as an automated, recurring process.
• To configure a database for maximum recoverability, Oracle
suggests regularly scheduled backups. Automating backups can
simplify the administrator’s workload.
• When you select Repeating, the page displays additional scheduling
details.
: Review
• RMAN uses its own command syntax and scripting language.
• Using this page, you can customize the RMAN scripts (if needed) or
copy them for recording purposes.

Backing Up the Control File to a Trace File
Control files have an additional backup option.
Control file trace backups
may be used to recover
from loss of all control files.

Backing Up the Control File to a Trace File
• Select Enterprise Manager > Server > Control Files to manage your database’s
control files. Control files have an additional backup option; they may be backed
up to a trace file. A control file trace backup contains the SQL statement required
to re-create the control files in the event that all control files are lost.
• Although it is very unlikely that a properly configured database (with multiple
copies of the control file placed on separate disks and separate controllers) would
lose all control files at the same time, it is possible. Therefore, the administrator
should back up the control file to a trace file after each change to the physical
structure of the database (adding tablespaces or data files, or adding additional
redo log groups).
• Trace copies of the control file can be created by using Enterprise Manager (as
shown in the slide) or with the following SQL command:
— SQL> ALTER DATABASE BACKUP CONTROLFILE TO TRACE;
• The trace backup is created in the location specified by the DIAGNOSTIC_DEST
initialization parameter (for example,
/u01/app/oracle/diag/rdbms/orcl/orcl/trace with a file name such
as orcl_vktm_8400.trc).
• You can view information from within the control file on the Advanced tab of the
Control Files page.

Managing Backups

Managing Backups
Select Enterprise Manager > Availability > Manage Current Backup to
manage your existing backups. On this page, you can see when a backup
was completed, where it was created (disk or tape), and whether it is still
available.
At the top of the Manage Current Backups page, four buttons enable you to
work with existing backups:
Catalog Additional Files: Although RMAN (working through Enterprise
Manager) is the recommended way to create backups, you might have image
copies or backup sets that were created by some other means or in some
other environment with the result that RMAN is not aware of them. This task
identifies those files and adds them to the catalog.
Crosscheck All: RMAN can automatically delete obsolete backups, but you
can also delete them by using operating system commands. If you delete a
backup without using RMAN, the catalog does not know whether the backup
is missing until you perform a cross-check between the catalog and what is
really there.
Delete All Obsolete: This deletes backups older than the retention policy.
Delete All Expired: This deletes the catalog listing for any backups that are
not found when the cross-check is performed.

Viewing Backup Reports

Viewing Backup Reports
Information about backup jobs can also be viewed by
selecting Enterprise Manager > Availability > Backup
Reports. The content is based on the control file. The
backup report contains summary information as well
as detailed information about the input and output of
a specific job, including timing, SCN, sizing,
compression, corruption (if any), and so on.

Monitoring the Fast Recovery Area

Monitoring the Fast Recovery Area
• If you have configured your archived logs to be written to this location, it is important
to monitor this space to ensure that it does not reach its capacity. If the instance is
unable to create an archived log because of lack of space, it pauses until the
administrator corrects the situation.
• Select Enterprise Manager > Availability > Recovery Settings. On this page, you
can:
– Verify how much of the fast recovery area has been consumed
– Specify the location of the fast recovery area
– Specify the size of the fast recovery area
– Configure Flashback Database
– Specify the retention time
• The retention time determines when files are obsolete (that is, when they are no
longer needed to meet your data recovery objectives). The Oracle database
automatically manages this storage, deleting files that are no longer needed. When
you back up the recovery area, RMAN can fail over to other archived redo log
destinations if the archived redo log in the fast recovery area is inaccessible or
corrupted.
• Periodically copying backups to tape frees space in the fast recovery area for other
files, but retrieving files from tape causes longer database restoration and recovery
times.
• Note: The Enterprise Manager interface has not yet been updated to reflect the
change in name from flash recovery area to fast recovery area.

Using the RMAN Command Line
$ rman target /
RMAN> CONFIGURE …
RMAN> BACKUP DATABASE PLUS ARCHIVELOG;
Control
file SPFILEArchived log
fileData files
Control
files
Copies of
1
2
3

Using the RMAN Command Line
1. In a terminal session, start RMAN and connect to the target database.
2. Execute configuration commands:
CONFIGURE DEFAULT DEVICE TYPE TO disk;
CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COPY;
CONFIGURE CONTROLFILE AUTOBACKUP ON;
3. A whole database backup is a copy of all data files and the control file. You can
optionally include the server parameter file (SPFILE) and archived redo log files.
Using RMAN to make an image copy of all the database files simply requires
mounting or opening the database, starting RMAN, and entering the BACKUP
command shown in the slide.
Optionally, you can supply the DELETE INPUT option when backing up archive
log files.
That causes RMAN to remove the archive log files after backing them up. This is
useful especially if you are not using a fast recovery area, which would perform
space management for you, deleting files when space pressure grows. In that
case, the command in the slide would look like the following:
RMAN> BACKUP DATABASE PLUS ARCHIVELOG DELETE INPUT;
You can also create a backup (either a backup set or image copies) of previous
image copies of all data files and control files in the database by using the
following command:
RMAN> BACKUP COPY OF DATABASE;

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