RMAN in Oracle

Oracle Recovery Manager (RMAN)

RMAN was introduced in Oracle8, RMAN has since been enhanced (in Oracle 9i), enhanced (in Oracle 10g) and enhanced (in Oracle 11g) and enhanced (in Oracle 12c ).

Recovery Manager(RMAN) is an Oracle provided (free) utility for backing-up, restoring and recovering Oracle databases. RMAN ships with the Oracle database and doesn't require a separate installation. The RMAN executable is located in $ORACLE_HOME/bin directory.

RMAN is a Pro*C application that translates commands to a PL/SQL interface through RPC (Remote Procedure Call). The PL/SQL calls are statically linked into the Oracle kernel, and does not require the database to be opened (mapped from the ?/rdbms/admin/recover.bsq file).

The RMAN environment consists of the utilities and databases that play a role in backing up our data. At a minimum, the environment for RMAN must include the following:

• The target database to be backed up.
  
• The RMAN client (rman executable and recover.bsq), which interprets backup and recovery commands, directs server sessions to execute those commands, and records our backup and recovery activity in the target database control file.

Some environments will also use these optional components:

• A recovery catalog database, a separate database schema used to record RMAN activity against one or more target databases (this is optional, but highly recommended).
  
• A flash recovery area, called as fast recovery area from 11g release2, a disk location in which the database can store and manage files related to backup and recovery.
  
• Media management software, required for RMAN to interface with backup devices such as tape drives.

Large pool (LARGE_POOL_SIZE) is used for RMAN.

Benefits of RMAN
Some of the benefits provided by RMAN include:

• Backups are faster and uses less tapes (RMAN will skip empty blocks)
  
• Less database archiving while database is being backed-up
  
• RMAN checks the database for block corruptions
  
• Automated restores from the catalog
  
• Files are written out in parallel instead of sequential

RMAN can be operated from OEM (Oracle Enterprise Manager), or from command line. Here are the command line arguments:

Argument	Value	Description
target	quoted-string	connect-string for target database
catalog	quoted-string	connect-string for recovery catalog
nocatalog	none	if specified, then no recovery catalog
cmdfile	quoted-string	name of input command file
log	quoted-string	name of output message log file
trace	quoted-string	name of output debugging message log file
append	none	if specified, log is opened in append mode
debug	optional-args	activate debugging
msgno	none	show RMAN-nnnn prefix for all messages
send	quoted-string	send a command to the media manager
pipe	string	building block for pipe names
timeout	integer	number of seconds to wait for pipe input
checksyntax	none	check the command file for syntax errors

$ rman
$ rman TARGET SYS/pwd@target

$ rman TARGET SYS/pwd@target NOCATALOG
$ rman TARGET SYS/pwd@target CATALOG rman/pwd@cat
$ rman TARGET=SYS/pwd@target CATALOG=rman/pwd@cat
$ rman TARGET SYS/pwd@target LOG $ORACLE_HOME/dbs/log/rman_log.log APPEND

$ rman TARGET / CATALOG rman/pwd@cat

$ rman TARGET / CATALOG rman/pwd@cat CMDFILE cmdfile.rcv LOG outfile.txt

$ rman CATALOG rman/pwd@cat$ rman @/my_dir/my_commands.txt


Using recovery catalog
One (base) recovery catalog can manage multiple target databases. All the target databases should be register with the catalog.


Start by creating a database schema (usually named rman), in catalog database. Assign an appropriate tablespace to it and grant it the recovery_catalog_owner role.

$ sqlplus "/as sysdba"
SQL> create user rman identified by rman default tablespace rmants quota unlimited on rmants;
SQL> grant resource, recovery_catalog_owner to rman;
No need to grant connect role explicitly, because recovery_catalog_owner role has it.

Log in to catalog database with rman and create the catalog.
$ rman catalog rman/rman
RMAN> create catalog;
RMAN> exit;

Now you can continue by registering your databases in the catalog.
$ rman catalog rman/rman@cat target system/manager@tgt
RMAN> register database;

Using virtual private catalog

A virtual private catalog is a set of synonyms and views that enable user access to a subset of a base recovery catalog. The owner of the base recovery catalog can GRANT or REVOKE restricted access to the catalog to other database users. Each restricted user has full read/write access to his own metadata, which is called a virtual private catalog. The RMAN metadata is stored in the schema of the virtual private catalog owner. The owner of the base recovery catalog controls what each virtual catalog user can access.

$ sqlplus "/as sysdba"
SQL> create user vpc identified by vpc default tablespace rmants quota unlimited on rmants;
SQL> grant resource, recovery_catalog_owner to vpc;

Log in to catalog database with rman and grant the catalog to vpc.
$ rman catalog rman/rman
RMAN> GRANT CATALOG FOR DATABASE target_db TO vpc;
RMAN> exit;

Log in to catalog database with vpc and create the virtual private catalog.
$ rman catalog vpc/vpc

RMAN> CREATE VIRTUAL CATALOG;

RMAN> exit;

$ sqlplus vpc/vpc

SQL>exec rman.DBMS_RCVCAT.CREATE_VIRTUAL_CATALOG;

Recovery Manager commands

ADVISE FAILURE	Will display repair options for the specified failures. 11g R1 command.
ALLOCATE	Establish a channel, which is a connection between RMAN and a database instance.
ALTER DATABASE	Mount or open a database.
BACKUP	Backup database, tablespaces, datafiles, control files, spfile, archive logs.
BLOCKRECOVER	Will recover the corrupted blocks.
CATALOG	Add information about file copies and user-managed backups to the catalog repository.
CHANGE	Update the status of a backup in the RMAN repository.
CONFIGURE	To change RMAN settings.
CONNECT	Establish a connection between RMAN and a target, auxiliary, or recovery catalog database.
CONVERT	Convert datafile formats for transporting tablespaces and databases across platforms.
CREATE CATALOG	Create the base/virtual recovery catalog.
CREATE SCRIPT	Create a stored script and store it in the recovery catalog.
CROSSCHECK	Check whether backup items still exist or not.
DELETE	Delete backups from disk or tape.
DELETE SCRIPT	Delete a stored script from the recovery catalog.
DROP CATALOG	Remove the base/virtual recovery catalog.
DROP DATABASE	Delete the target database from disk and unregisters it.
DUPLICATE	Use backups of the target database to create a duplicate database that we can use for testing purposes or to create a standby database.
EXECUTE SCRIPT	Run an RMAN stored script.
EXIT or QUIT	Exit/quit the RMAN console.
FLASHBACK DATABASE	Return the database to its state at a previous time or SCN.
GRANT	Grant privileges to a recovery catalog user.
HOST	Invoke an operating system command-line subshell from within RMAN or run a specific operating system command.
IMPORT CATALOG	Import the metadata from one recovery catalog into another recovery catalog.
LIST	List backups and copies.
PRINT SCRIPT	Display a stored script.
RECOVER	Apply redo logs or incremental backups to a restored backup set in order to recover it to a specified time.
REGISTER	Register the target database in the recovery catalog.
RELEASE CHANNEL	Release a channel that was allocated.
REPAIR FAILURE	Will repair database failures identified by the Data Recovery Advisor. 11g R1 command.
REPLACE SCRIPT	Replace an existing script stored in the recovery catalog. If the script does not exist, then REPLACE SCRIPT creates it.
REPORT	Report backup status - database, files, backups.
RESET DATABASE	Inform RMAN that the SQL statement ALTER DATABASE OPEN RESETLOGS has been executed and that a new incarnation of the target database has been created, or reset the target database to a prior incarnation.
RESTORE	Restore files from RMAN backup.
RESYNC CATALOG	Perform a full resynchronization, which creates a snapshot control file and then copies any new or changed information from that snapshot control file to the recovery catalog.
REVOKE	Revoke privileges from a recovery catalog user.
RUN	To run set of RMAN commands, only some RMAN commands are valid inside RUN block.
SEND	Send a vendor-specific quoted string to one or more specific channels.
SET	Settings for the current RMAN session.
SHOW	Display the current configuration.
SHUTDOWN	Shutdown the database.
SPOOL	To direct RMAN output to a log file.
SQL	Execute a PL/SQL procedure or SQL statement (not SELECT).
STARTUP	Startup the database.
SWITCH	Specify that a datafile copy is now the current datafile, that is, the datafile pointed to by the control file.
TRANSPORT TABLESPACE	Create transportable tablespace sets from backup for one or more tablespaces.
UNREGISTER	Unregister a database from the recovery catalog.
UPGRADE CATALOG	Upgrade the recovery catalog schema from an older version to the version required by the RMAN executable.
VALIDATE	To validate. 11g R1 command.

All RMAN commands executed through channels. A channel is a connection (session) from RMAN to target database. These connections or channels are used to perform the desired operations.


Flash/Fast Recovery Area (FRA)
Flash recovery area is a disk location in which the database can store and manage files related to backup and recovery.
To set the flash recovery area location and size, use DB_RECOVERY_FILE_DEST and DB_RECOVERY_FILE_DEST_SIZE.

RMAN new features in Oracle 10g

• Managing recovery related files with flash recovery area.
• Optimized incremental backups using block change tracking (Faster incremental backups) using a file (named block change tracking file). CTWR (Change Tracking Writer) is the background process responsible for tracking the blocks.
• Reducing the time and overhead of full backups with incrementally updated backups.
• Comprehensive backup job tracking and administration with Enterprise Manager (OEM).
• Backup set binary compression.
• New compression algorithm BZIP2 brought in.
• Automated Tablespace Point-in-Time Recovery.
• Automatic channel failover on backup & restore.
• Cross-Platform tablespace conversion.
• Ability to preview the backups required to perform a restore operation.
  RMAN> restore database preview [summary];
  RMAN> restore tablespace tbs1 preview;

RMAN new features in Oracle 11g Release 1

• Multisection backups of same file - RMAN can backup or restore a single file in parallel by dividing the work among multiple channels. Each channel backs up one file section, which is a contiguous range of blocks. This speeds up overall backup and restore performance, and particularly for bigfile tablespaces, in which a datafile can be sized upwards of several hundred GB to TB's.
• Recovery will make use of flashback logs in FRA (Flash Recovery Area).
• Fast Backup Compression - in addition to the Oracle Database 10^g backup compression algorithm (BZIP2), RMAN now supports the ZLIB algorithm, which offers 40% better performance, with a trade-off of no more than 20% lower compression ratio, versus BZIP2.
  RMAN> configure compression algorithm 'ZLIB' ;
• Will backup uncommitted undo only, not committed undo.
• Data Recovery Advisor (DRA) - quickly identify the root cause of failures; auto fix or present recovery options to the DBA.
• Virtual Private Catalog - a recovery catalog administrator can grant visibility of a subset of registered databases in the catalog to specific RMAN users.
  RMAN> grant catalog for database db-name to user-name;
  
• Catalogs can be merged/moved/imported from one database to another.
• New commands in RMAN
  • RMAN> list failure;
  • RMAN> list failure errnumber detail;
  • RMAN> advise failure;
  • RMAN> repair failure;
  • RMAN> repair failure preview;
  • RMAN> validate database; -- checks for corrupted blocks
  • RMAN> create virtual catalog;

RMAN new features in Oracle 11g Release2

• The following are new clauses and format options for the SET NEWNAME command:A single SET NEWNAME command can be applied to all files in a database or tablespace.
  SET NEWNAME FOR DATABASE TO format;
  SET NEWNAME FOR TABLESPACE tsname TO format;
• # New format identifiers are as follows:
  # %U - Unique identifier. data_D-%d_I-%I_TS-%N_FNO-%f
  # %b - UNIX base name of the original datafile name. For example, if the original datafile name was $ORACLE_HOME/data/tbs_01.f, then %b is tbs_01.f.

RMAN related views

Control File V$ View	Recovery Catalog View	View Describes
V$ARCHIVED_LOG	RC_ARCHIVED_LOG	Archived and unarchived redo logs
V$BACKUP_DATAFILE	RC_BACKUP_CONTROLFILE	Control files in backup sets
V$BACKUP_CORRUPTION	RC_BACKUP_CORRUPTION	Corrupt block ranges in datafile backups
V$BACKUP_DATAFILE	RC_BACKUP_DATAFILE	Datafiles in backup sets
V$BACKUP_FILES	RC_BACKUP_FILES	RMAN backups and copies in the repository
V$BACKUP_PIECE	RC_BACKUP_PIECE	Backup pieces
V$BACKUP_REDOLOG	RC_BACKUP_REDOLOG	Archived logs in backups
V$BACKUP_SET	RC_BACKUP_SET	Backup sets
V$BACKUP_SPFILE	RC_BACKUP_SPFILE	Server parameter files in backup sets
V$DATAFILE_COPY	RC_CONTROLFILE_COPY	Control file copies on disk
V$COPY_CORRUPTION	RC_COPY_CORRUPTION	Information about datafile copy corruptions
V$DATABASE	RC_DATABASE	Databases registered in the recovery catalog (RC_DATABASE) or information about the currently mounted database (V$DATABASE)
V$DATABASE_ BLOCK_CORRUPTION	RC_DATABASE_ BLOCK_CORRUPTION	Database blocks marked as corrupt in the most recent RMAN backup or copy
V$DATABASE_INCARNATION	RC_DATABASE_INCARNATION	All database incarnations registered in the catalog
V$DATAFILE	RC_DATAFILE	All datafiles registered in the recovery catalog
V$DATAFILE_COPY	RC_DATAFILE_COPY	Datafile image copies
V$LOG_HISTORY	RC_LOG_HISTORY	Historical information about online redo logs
V$OFFLINE_RANGE	RC_OFFLINE_RANGE	Offline ranges for datafiles
V$PROXY_ARCHIVEDLOG	RC_PROXY_ARCHIVEDLOG	Archived log backups created by proxy copy
V$PROXY_CONTROLFILE	RC_PROXY_CONTROLFILE	Control file backups created by proxy copy
V$PROXY_DATAFILE	RC_PROXY_DATAFILE	Datafile backups created by proxy copy
V$LOG and V$LOGFILE	RC_REDO_LOG	Online redo logs for all incarnations of the database since the last catalog resynchronization
V$THREAD	RC_REDO_THREAD	All redo threads for all incarnations of the database since the last catalog resynchronization
V$RESTORE_POINT	RC_RESTORE_POINT	All restore points for all incarnations of the database since the last catalog resynchronization
-	RC_RESYNC	Recovery catalog resynchronizations
V$RMAN_CONFIGURATION	RC_RMAN_CONFIGURATION	RMAN persistent configuration settings
V$RMAN_OUTPUT	RC_RMAN_OUTPUT	Output from RMAN commands for use in Enterprise Manager
V$RMAN_STATUS	RC_RMAN_STATUS	Historical status information about RMAN operations
V$TABLESPACE	RC_TABLESPACE	All tablespaces registered in the recovery catalog, all dropped tablespaces, and tablespaces that belong to old incarnations
V$TEMPFILE	RC_TEMPFILE	All tempfiles registered in the recovery catalog

RMAN related Packages

DBMS_RCVCAT

DBMS_RCVMAN
DBMS_BACKUP_RESTORE

Related Oracle Articles: RMAN (Recovery Manager) commands in Oracle  RMAN Incremental Backups