WHAT IS RMAN ?
Recovery Manager is a tool
that: manages the process of creating backups and also manages the process of
restoring and recovering from them.
WHY USE RMAN ?
·
No extra costs
…Its available free
·
RMAN introduced
in Oracle 8 it has become simpler with newer versions and easier than user
managed backups
·
Proper security
·
You are 100%
sure your database has been backed up.
·
Its contains
detail of the backups taken etc in its central repository
·
Facility for
testing validity of backups also commands like crosscheck to Check the status
of backup.
·
Faster backups
and restores compared to backups without RMAN
·
RMAN is the only
backup tool which supports incremental backups.
·
Oracle 10g has
got further optimized incremental backup which has resulted in improvement of
performance during backup and recovery time
·
Parallel
operations are supported
·
Better querying
facility for knowing different details of backup
·
No extra redo
generated when backup is taken..compared to online backup without RMAN which
results in saving of space in hard disk
·
RMAN an
intelligent tool
·
Maintains
repository of backup metadata
·
Remembers backup
set location
·
Knows what need
to backed up
·
Knows what is
required for recovery
·
Knows what
backup are redundant
UNDERSTANDING THE RMAN ARCHITECTURE
An oracle RMAN comprises of
RMAN EXECUTABLE. This could be present and fired even through client side
TARGET DATABASE. This is the database which needs to be backed up
RECOVERY CATALOG - Recovery catalog is optional
otherwise backup details are stored in target database controlfile
It is a repository of
information queried and updated by Recovery Manager
It is a schema or user
stored in Oracle database
One schema can support many
databases
It contains information
about physical schema of target database datafile and archive log, backup sets
and pieces
Recovery catalog is a must in following scenarios
·
In order to
store scripts
·
For tablespace
point in time recovery
Media Management Software
Media Management software is
a must if you are using RMAN for storing backup in tape drive directly.
Backups in RMAN
Oracle backups in RMAN are
of the following type
·
RMAN complete
backup OR RMAN incremental backup
These
backups are of RMAN proprietary nature.
·
IMAGE COPY
It’s
again a kind of backup. The advantage of using Image copy is it’s not in RMAN
proprietary format.
Backup Format
RMAN backup is not in oracle
format but in RMAN format. Oracle backup comprises of backup sets and it
consists of backup pieces. Backup sets are logical entity. In oracle 9i it gets
stored in a default location.
There are two type of backup
sets
·
Datafile backup
sets,
·
Archivelog
backup sets
One more important point of data file backup sets
is it does not include empty blocks. A backup set would contain many backup pieces. A
single backup piece consists of physical files which are in RMAN proprietary
format.
You can go to RMAN prompt by
just typing rman. RMAN executable is present in ORACLE_HOME/bin location.
bash-2.05$ rman
Recovery Manager:
Release 10.2.0.1.0 – Production on Mon Jul 23 02:16:55 2007Copyright (c) 1982,
2005, Oracle. All rights reserved.
RMAN>
You can use target connect
to connect to database. The database it will connect to depends on the
environment variable ORACLE_HOME.
RMAN> connect target
connected to
target database: ORCL (DBID=1156435946)
Alternatively you can use “rman
TARGET SYS/oracle@test NOCATALOG” to connect to the RMAN of “test” instance.
Here we will be using target
database control file to store all the information required for RMAN, like
backupsets and backup image information etc.
Backup Database:
RMAN> shutdown
immediate
using target
database control file instead of recovery catalog
database closed
database dismounted
Oracle instance shut down
RMAN> startup mount;
connected to
target database (not started)
Oracle instance started
database mountedTotal System Global Area 1258291200 bytes
Fixed
Size
1978336 bytes
Variable
Size
318771232 bytes
Database
Buffers
922746880 bytes
Redo
Buffers
14794752 bytes
RMAN> backup
database;
Starting backup
at 23-JUL-07
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=155 devtype=DISK
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00001 name=/dy/oracle/product/oradata/orcl/system01.dbf
input datafile fno=00003 name=/dy/oracle/product/oradata/orcl/sysaux01.dbf
input datafile fno=00005 name=/dy/oracle/product/oradata/orcl/example01.dbf
input datafile fno=00002 name=/dy/oracle/product/oradata/orcl/undotbs01.dbf
input datafile fno=00004 name=/dy/oracle/product/oradata/orcl/users01.dbf
channel ORA_DISK_1: starting piece 1 at 23-JUL-07
channel ORA_DISK_1: finished piece 1 at 23-JUL-07
piece handle=/dy/oracle/product/flash_recovery_area/ORCL/backupset/2007_07_23/
o1_mf_nnndf_TAG20070723T031355_3b8zv57d_.bkp
tag=TAG20070723T031355 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:36
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
including current control file in backupset
including current SPFILE in backupset
channel ORA_DISK_1: starting piece 1 at 23-JUL-07
channel ORA_DISK_1: finished piece 1 at 23-JUL-07
piece handle=/dy/oracle/product/flash_recovery_area/ORCL/backupset/2007_07_23/
o1_mf_ncsnf_TAG20070723T031355_3b8zy7xr_.bkp
tag=TAG20070723T031355 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:06
Finished backup at 23-JUL-07
Creating RMAN Catalog
You can also create a
repository for RMAN to store all this information. Repository will be just
another small database which can store the catalog information. Creating a
catalog is a 3 step process
1) Create database which
will hold the catalog. Else you can use the existing database also. All you
need is to create a seperate tablespace for holding the information about RMAN
catalog.
2) Create RMAN tablespace
and RMAN user
SQL> create
tablespace rman_tbs datafile ‘/dy/oracle/product/db10g/dbf/rman01.dbf’ size
500M EXTENT MANAGEMENT LOCAL segment SPACE MANAGEMENT AUTO ;
Tablespace
created.
SQL> create user
rman identified by rman
2 default tablespace rman_tbs
3 TEMPORARY TABLESPACE TEMPTS1
4 QUOTA UNLIMITED ON rman_tbs account unlock;
User created.
After creating user, you
need to grant RECOVERY_CATALOG_OWNER role to that user.
SQL> grant
recovery_catalog_owner to rman;
Grant succeeded.
3) Now Create RMAN
catalog.
bash-2.05$ rman catalog
rman/rman@test
Recovery Manager:
Release 10.2.0.1.0 – Production on Mon Jul 23 04:37:10 2007Copyright (c) 1982,
2005, Oracle. All rights reserved.
connected to
recovery catalog database
RMAN> create catalog
recovery catalog
created
For registering the
database, you need to get connected to database as well as catalog at the same
time. Here is how you can do.
RMAN> connect target
RMAN-00571:
===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-06004: ORACLE error from recovery catalog database: RMAN-20001: target
database not found in recovery catalog
The above error is because
the database we connected to is not found in the catalog database. We can
register the database in catalog.
RMAN> register
database;
database
registered in recovery catalog
starting full resync of recovery catalog
full resync complete
Registering database will
also resynch the information present in the target database control file and
catalog database. Since we have taken 1 backup early, it will synchup that
information with RMAN catalog. We can check the same using LIST BACKUP command
at RMAN prompt.
RMAN> list backup;
List of Backup
Sets
===================
o1_mf_nnndf_TAG20070723T031355_3b8zv57d_.bkp
List of Datafiles in backup set 18
File LV Type Ckp SCN Ckp Time Name
—- — —- ———- ——— —-
1 Full 562487
23-JUL-07 /dy/oracle/product/oradata/orcl/system01.dbf
2 Full 562487
23-JUL-07 /dy/oracle/product/oradata/orcl/undotbs01.dbf
3 Full 562487
23-JUL-07 /dy/oracle/product/oradata/orcl/sysaux01.dbf
4 Full 562487
23-JUL-07 /dy/oracle/product/oradata/orcl/users01.dbf
5 Full 562487
23-JUL-07 /dy/oracle/product/oradata/orcl/example01.dbf
BS Key Type
LV Size Device Type Elapsed Time Completion
Time
——- —- — ———- ———– ———— —————
19 Full
6.80M
DISK 00:00:05
23-JUL-07
BP Key: 21 Status: AVAILABLE Compressed: NO Tag:
TAG20070723T031355
Piece Name: /dy/oracle/product/flash_recovery_area/ORCL/backupset/2007_07_23/
o1_mf_ncsnf_TAG20070723T031355_3b8zy7xr_.bkp
Control File Included: Ckp SCN: 562487 Ckp
time: 23-JUL-07
SPFILE Included: Modification time: 23-JUL-07
RMAN Command line
Backing up the Controlfile
and Spfile
The control file can be
automatically backed up after each RMAN backup and database structure change as
a way to protect the RMAN repository (when we are not using a seperate catalog
for RMAN).
RMAN> configure controlfile autobackup on;
Backing up control file
RMAN> backup current
controlfile;
Creating Image copy of all datafiles in
database
These are the image copies
and are stored in ORACLE format and not in RMAN format. Backupsets and
backuppieces are stored in internal RMAN format. Hence these image copies can
be used for manual restore and recovery as well.
RMAN> backup as copy
database;
Creating backupsets of all datafiles in
database
If you specify BACKUP AS
BACKUPSET, then RMAN stores its backups in backup sets. A backup set,
consisting of one or more backup pieces, contains the physical file data being
backed up. This backupset is written in a format that only RMAN can
access. Only RMAN can create and restore backup sets. Backup sets can be
written to disk or tape, and they are the only type of backup which RMAN can
use to write backups to tape.
RMAN> backup as backupset
database;
Backup individual tablespace as backupsets
RMAN> backup
tablespace system, HTMLDB;
Backup individual tablespace as image copies
RMAN> backup as copy
tablespace system;
Backup individual files as image copies
RMAN> backup as copy
datafile ‘/dy/oracle/product/db10g/dbf/system01.dbf’;
Backup individual files as Backupsets
RMAN> backup
datafile ‘/dy/oracle/product/db10g/dbf/system01.dbf’;
Backup archivelogs
We can backup the archive
logs according to the output of some search condition. Example we want to
backup only those archivelogs which starts with “ARCH_616814159_”.
RMAN> backup
acrchivelog like ‘%ARCH_616814159_%’;
Copy archivelogs from some time stamp.
Suppose we want to copy the
archivelogs of last 2 days, then we can use the following commands.
RMAN> BACKUP
ARCHIVELOG from time ’sysdate-2′;
Backup all archivelog files
RMAN> Backup
archivelog all;
Backup archivelog between some time.
RMAN> BACKUP
ARCHIVELOG FROM TIME ‘SYSDATE-30′ UNTIL TIME ‘SYSDATE-7′;
Specifying copies while backing up.
RMAN> backup copies
2 datafile ‘/dy/oracle/product/db10g/dbf/cs_tbs01.dbf’;
Remember that copies option
cannot be used with image copies. It can be used only with backupsets.
Giving tags to backups
RMAN> BACKUP TAG
‘weekly_full_db_bkup’ DATABASE MAXSETSIZE 100M;
Backing up backupsets
RMAN> BACKUP BACKUPSET ALL;
Backup imagecopies
RMAN> Backup as copy
backupset all;
List Imagecopies
RMAN> list copy;
List Backupsets
RMAN> list backup;
Restoring and Recovering the database
Use the RESTORE and RECOVER
commands for RMAN restore and recovery of physical database files.
RMAN> STARTUP FORCE
MOUNT;
RESTORE DATABASE;
RECOVER DATABASE;
ALTER DATABASE OPEN;
Recovering Current Tablespaces
RMAN> SQL ‘ALTER
TABLESPACE users OFFLINE’;
RESTORE TABLESPACE users;
RECOVER TABLESPACE users;
SQL ‘ALTER TABLESPACE users ONLINE;
Recovering Current Datafiles
RMAN> SQL ‘ALTER
DATABASE DATAFILE 7 OFFLINE’;
RESTORE DATAFILE 7;
RECOVER DATAFILE 7;
SQL ‘ALTER DATABASE DATAFILE 7 ONLINE’;
Recovering Individual Data Blocks
RMAN can recover individual
corrupted datafile blocks. When RMAN performs a complete scan of a file for a
backup, any corrupted blocks are listed in V$DATABASE_BLOCK_CORRUPTION.
Corruption is usually reported in alert logs, trace files or results of SQL
queries. Use BLOCKRECOVER to repair all corrupted blocks:
RMAN> BLOCKRECOVER CORRUPTION LIST;
You can also recover
individual blocks, as shown in this example:
RMAN> BLOCKRECOVER DATAFILE 7 BLOCK 233, 235 DATAFILE 4 BLOCK 101;
Managing RMAN repository
As you know that if you do
not use a recovery catalog, then control file of the target database is used as
RMAN repository and eventually after some time the control file records for
RMAN information will get overwritten.
Set this initialization parameter in the parameter file of the target database
to determine how long records are kept:
CONTROL_FILE_RECORD_KEEP_TIME
=
You can configure a
retention policy to be used by RMAN to determine which backups are considered
obsolete. This allows you to remove files from the repository that are no
longer needed to meet your retention requirements. This policy can be
based on a recovery window (the maximum number of days into the past for which
you can recover) or redundancy (how many copies of each backed-up file to
keep).
Two Parameters are used to set retention policies.
You can specify the days
days between the current time and the earliest point of recoverability, this is
called RECOVERY WINDOW. RMAN does not consider any full or level 0
incremental backup as obsolete if it falls within the recovery window.
Alternatively the REDUNDANCY parameter will instruct to store the
number of copies of backup in RMAN repository. If the number of backups for a
specific datafile or control file exceeds the REDUNDANCY setting considers the
extra backups as obsolete.
RMAN> CONFIGURE RETENTION POLICY TO
REDUNDANCY 3;
This will make the
REDUNDANCY setting to 3. Meaning that it will at max store 3 copies of backups
and ikmages of datafile. Any more images or backups are consider obsolete.
When we run the below
command
RMAN> CONFIGURE RETENTION POLICY TO
RECOVERY WINDOW OF 7 DAYS;
it will configure new
retention policy based on the RECOVERY WINDOW of 7 days. This means that all
the backups which falls outside this window will be considered obsolute. So in
this case you need to have backup scheduled every week to have atleast 1 valid
backup.
Remember that at any point
of time, only one policy can be active. It can be either REDUNDANCY or RECOVERY
WINDOW.
When you change the
retention policy to another one, it will suspend the previous policy as shown
below.
RMAN> CONFIGURE RETENTION POLICY TO
RECOVERY WINDOW OF 7 DAYS;
old RMAN
configuration parameters:
CONFIGURE RETENTION POLICY TO REDUNDANCY 3;
new RMAN configuration parameters:
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;
new RMAN configuration parameters are successfully stored
starting full resync of recovery catalog
full resync complete
Cross checking the available backups
RMAN> CROSSCHECK BACKUP;
Crosscheck is needed when an
archivelog file or backup is manually removed, i.e., not deleted by RMAN.
This command ensures that data about backups in the recovery catalog or control
file is synchronized with corresponding data on disk or in the media management
catalog. The CROSSCHECK command operates only on files that are recorded
in the recovery catalog or the control file.
The CROSSCHECK command does
not delete any files that it is unable to find, but updates their repository
records to EXPIRED. Then, you can run DELETE EXPIRED to remove the repository
records for all expired files as well as any existing physical files whose
records show the status EXPIRED.
If some backup pieces or
copies were erroneously marked as EXPIRED, for example, because the media
manager was misconfigured, then after ensuring that the files really do exist
in the media manager, run the CROSSCHECK BACKUP command again to restore those
files to AVAILABLE status.
RMAN> CROSSCHECK COPY;
This will validate the image
copies.
Deleting the backups
The DELETE command removes
RMAN backups and copies from DISK marks the records in control file as DELETED
or removes the records from the recovery catalog (if you use a catalog).
RMAN> DELETE BACKUPSET 101, 102, 103;
RMAN> delete controlfilecopy ‘%ctl’;
# Pattern search is allowed.
RMAN> delete archivelog until sequence 20;
This will delete all the
archives from the oldest one till the sequence we have specified.
RMAN> delete backup of tablespace system;
RMAN> DELETE ARCHIVELOG ALL BACKED UP 2
TIMES TO DEVICE TYPE DISK;
List commands
RMAN> list backup;
RMAN> list copy;
RMAN> list incarnation of database;
RMAN> list expired backupset;
RMAN> list expired copy;
RMAN> list backup of tablespace sysaux;
RMAN> list copy of datafile 3;
Reporting in RMAN
RMAN> report need backup;
Reports which database files need to be backed up
to meet a configured or specified retention policy
RMAN> report unrecoverable;
Reports which database files
require backup because they have been affected by some NOLOGGING operation such
as a direct-path insert
RMAN> report need backup recovery window of
7 days;
Displays objects requiring
backup to satisfy a recovery window-based retention policy.
Suppose in the above command
we want to skip a perticular tablespace like perfstat then we can use the below
command.
RMAN> report need backup recovery window of
2 days database skip tablespace perfstat;
RMAN> report need backup redundancy 3;
Displays objects requiring
backup to satisfy a redundancy-based retention policy.
RMAN> report need backup days 7;
Displays files that require
more than n days’ worth of archived redo log files for recovery.
RMAN> report need backup incremental 7;
Displays files that require
application of more than n incremental backups for recovery.
RMAN> report need backup redundancy 2
datafile 3;
Gives report of files with
less than 2 redundant backups.
RMAN> report need backup tablespace htmldb;
Report of files that must be
backed up to satisfy current retention policy for this tablespace (htmldb)
RMAN> report need backup incremental 2;
Report of files that need
more than 2 incrementals during recovery
RMAN> report need backup device type disk;
Report of files that must be
backed up to satisfy current retention policy for database
RMAN> report obsolete;
Shows backups that are obsolete according to the current retention policy.
You can add the options
RECOVERY WINDOW and REDUNDANCY with this command as given below.
RMAN> report obsolete recovery window of 3
days;
RMAN> report obsolete redundancy 2;
RMAN> report schema;
This command lists and
displays information about the database files.
RMAN> report schema at time ’sysdate – 14′;
This command gives report on
schema 14 days ago.
RMAN> report schema at SCN 10000;
This gives report on schema
at scn 10000.
RMAN> report schema at sequence 55 thread
1;
Gives report of schema at
sequence 55.
RMAN configuration
RMAN> show all;
RMAN configuration
parameters are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP ON;
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘%F’; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM ‘AES128′; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO ‘/dy/oracle/product/db10g/dbs/snapcf_test.f’;
# default
We can change each of these
parameters as per our requirements.
You can return any setting to
its default value by using CONFIGURE… CLEAR
RMAN> CONFIGURE BACKUP OPTIMIZATION CLEAR;
RMAN> CONFIGURE RETENTION POLICY CLEAR;
By default, RMAN sends all
backups to an operating system specific directory on disk. So default setting
for DEVICE TYPE is DISK. You can configure to make backups by default on tape
or any other device as given below.
RMAN> CONFIGURE DEFAULT DEVICE TYPE TO sbt;
You can configure backup
sets or image copies as the default for a perticular device type, using either
of the following commands:
RMAN> CONFIGURE DEVICE TYPE DISK BACKUP
TYPE TO COPY;# Default becomes image copies
RMAN> CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO BACKUPSET; #
Default becomes uncompressed
You can configure RMAN to
use compressed backupsets by default on a particular device type, by using the
CONFIGURE DEVICE TYPE command with the BACKUP TYPE TO COMPRESSED BACKUPSET
option, as shown in the following examples.
RMAN> CONFIGURE DEVICE TYPE DISK BACKUP
TYPE TO COMPRESSED BACKUPSET;
RMAN> CONFIGURE DEVICE TYPE sbt BACKUP TYPE
TO COMPRESSED BACKUPSET;
To disable compression you
can use below command
RMAN> CONFIGURE DEVICE TYPE DISK BACKUP
TYPE TO BACKUPSET;
RMAN> CONFIGURE DEVICE TYPE sbt BACKUP TYPE
TO BACKUPSET;
You can configure the
parallelism for a device type.
RMAM> CONFIGURE DEVICE TYPE sbt PARALLELISM
2;
You can turn on/off
controlfile autobackup using
RMAN> configure controlfile autobackup off;
RMAN> configure controlfile autobackup on;
We can configure RMAN
channel to write backups and images in a specific format.
The following command
configures RMAN to write disk backups to the /backup directory
CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT
‘/backup/ora_df%t_s%s_s%p’;
%t is replaced with a four
byte time stamp,
%s with the backup set number, and
%p with the backup piece number.
You can also configure
format for controlfile autobackup as well.
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT
FOR DEVICE TYPE deviceSpecifier TO ’string’;
For example, you can run the
following command:
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE
TYPE DISK TO ‘?/oradata/cf_%F’;
Here %F will be replaced by
following
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
You can clear the format
using following command.
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT
FOR DEVICE TYPE DISK CLEAR;
