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Oracle® Database Backup and Recovery Reference
11g Release 1 (11.1)

B28273-03
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BACKUP

Purpose

Use the BACKUP command to back up a primary or standby database, tablespace, datafile (current or copy), control file (current or copy), server parameter file, archived redo log file, or backup set.

Additional Topics

Prerequisites

RMAN must be connected to a target database. See the CONNECT and RMAN commands to learn how to connect to a database as TARGET.

Database Archiving Modes

If the target database is in ARCHIVELOG mode, then the database must be mounted or open with a current control file. Backups made while the database is open are inconsistent. You must apply redo logs after restoring an inconsistent backup to make the database consistent.

If the target database is in NOARCHIVELOG mode, then the database must be mounted after a consistent shutdown when you make the backup. The shutdown is only consistent if you successfully execute the SHUTDOWN command with the NORMAL, IMMEDIATE, or TRANSACTIONAL options. You cannot use RMAN to back up a NOARCHIVELOG database after an instance failure or SHUTDOWN ABORT.

Backup Media

RMAN can only back up files onto valid media. If you specify DEVICE TYPE DISK, then RMAN makes backups to random access disks. You can make a backup on any device that can store a datafile. If the statement CREATE TABLESPACE tablespace_name DATAFILE 'filename' works, then 'filename' is a valid backup path name. If you specify DEVICE TYPE sbt, then you can back up files to any media supported by the media manager.

When backing up Oracle Database files to disk, the logical block size of the files must be an even multiple of the physical block size of the destination device. For example, a disk device with a block size of 2 KB can only be used as a destination for backups of Oracle files with logical block sizes of 2 KB, 4 KB, 6 KB and so on. In practice, most disk drives have physical block sizes of 512 bytes, so this limitation rarely affects backup. However, you can encounter this limitation when using BACKUP ... DEVICE TYPE DISK to back your database up to a writeable CD or DVD, or some other device that has a larger physical block size.

Channels

If no automatic channel is configured for the specified device type, then you must manually allocate a channel for each BACKUP execution. If no manual channel is allocated, then RMAN uses the default channels set with the CONFIGURE command. RMAN has a DISK channel preconfigured but no preconfigured sbt channels.

Note:

Backups that use the disk test API are not supported for production backups. Instead, use the preconfigured DISK channel or manually allocate a DISK channel.

Usage Notes

RMAN can only back up datafiles, control files, server parameter files, archived redo log files, and RMAN backups of these files. RMAN cannot make backups of other database-related files such as network configuration files, password files, the block change tracking file, and the contents of the Oracle home directory. Likewise, some features of Oracle Database, such as external tables or the BFILE datatype, store data in files other than those in the preceding list. RMAN cannot back up these files.

RMAN decomposes a BACKUP command into multiple independent backup steps. RMAN can execute each independent step on any channel allocated for a specific device. If multiple channels are allocated, and if one channel fails or encounters a problem during a backup step, then RMAN attempts to complete the work on another channel. RMAN reports a message in V$RMAN_OUTPUT and in the output to the interactive session or log file when channel failover occurs.

RMAN backups made on one platform are not transportable to a different platform.

RMAN backups made in a previous release of Oracle Database are usable after a database migration or upgrade.

If you change the DB_NAME for a database, but not its DBID, then RMAN considers backups made of the database with the previous DB_NAME as eligible to be restored.

Incremental Backups

An INCREMENTAL backup at level 0 backs up all data blocks in datafiles being backed up. An incremental backup at level 0 is identical in content to a FULL backup, but unlike a full backup the level 0 backup is a part of the incremental backup strategy.

A level 1 backup copies only changed blocks. A level 1 incremental backup is either differential or CUMULATIVE. If cumulative, RMAN backs up all blocks changed since the most recent level 0 backup. If differential, RMAN backs up blocks updated since the most recent level 0 or level 1 incremental backup. You can apply a level 1 backup of a standby database to a level 0 backup of a primary database, and also apply a level 1 backup of a primary database to a level 0 backup of a standby database.

Incremental backups at level 0 can be either backup sets or image copies, but incremental backups at level 1 can only be backup sets.

The database performs checks when attempting to create a level 1 incremental backup to ensure that the incremental backup is usable by a subsequent RECOVER command. Among the checks performed are:

Note:

When creating an incremental backup, RMAN considers backups from parent incarnations as valid. For example, assume you make a level 0 backup and then OPEN RESETLOGS. If you make a level 1 incremental backup, then RMAN backs up all blocks changed since the pre-RESETLOGS level 0 backup. When making a level 1 backup, RMAN only makes a new level 0 backup if no level 0 is available in either the current or parent database incarnation.

You can improve incremental backup performance by enabling block change tracking on a primary or standby database. In this case, RMAN keeps a record of which blocks have changed in the block change tracking file.

The change tracking file maintains bitmaps that mark changes in the datafiles between backups. The database performs a bitmap switch before each backup. Oracle Database automatically manages space in the change tracking file to retain block change data that covers the 8 most recent backups. After the maximum of 8 bitmaps is reached, the most recent bitmap is overwritten by the bitmap that tracks the current changes.

The first level 0 incremental backup scans the entire datafile. Subsequent incremental backups use the block change tracking file to scan only the blocks that have been marked as changed since the last backup. An incremental backup can be optimized only when it is based on a parent backup that was made after the start of the oldest bitmap in the block change tracking file.

Consider the 8-bitmap limit when developing your incremental backup strategy. For example, if you make a level 0 database backup followed by 7 differential incremental backups, then the block change tracking file now includes 8 bitmaps. If you then make a cumulative level 1 incremental backup, RMAN cannot optimize the backup because the bitmap corresponding to the parent level 0 backup is overwritten with the bitmap that tracks the current changes.

See Also:

Oracle Database Backup and Recovery User's Guide for details about block change tracking

Encryption of Backup Sets

RMAN can transparently encrypt data written to backup sets and decrypt those backup sets when they are needed in a RESTORE operation. To create encrypted backups on disk, the database must use the Advanced Security Option. To create encrypted backups directly on tape, RMAN must use the Oracle Secure Backup SBT interface, but does not require the Advanced Security Option. RMAN issues an ORA-19916 error if you attempt to create encrypted RMAN backups using an SBT library other than Oracle Secure Backup.

RMAN can encrypt backups by using several different encryption algorithms, which are listed in V$RMAN_ENCRYPTION_ALGORITHMS. RMAN supports three modes of encryption for backups:

Note:

Wallet-based encryption is more secure than password-based encryption because no passwords are involved. You should use password-based encryption only when absolutely necessary because your backups must be transportable.

The CONFIGURE and SET commands are used to manage the encryption settings for database backups. See the reference entries for those commands for more details. Backup sets containing archived logs are encrypted if any of the following are true:

See Also:

RMAN Backups in a Data Guard Environment

A recovery catalog is required when you are performing RMAN operations in a Data Guard environment. The catalog enables all RMAN operations to be transparently executable at any primary or standby database. You can offload primary database backups onto any standby database in the environment; the RMAN backups are interchangeable. If you use RMAN in NOCATALOG mode, then RMAN uses only the metadata in the mounted control file.

In a Data Guard environment, the database that creates a backup or copy is associated with the file. For example, if RMAN connects as TARGET to database prod and backs it up, then this database backup is associated with prod. A backup remains associated with the database that created in unless you use the CHANGE ... RESET DB_UNIQUE_NAME to associate the backup with a different database.

The association of a backup is different from its accessibility. The recovery catalog considers disk backups as accessible only to the database in the Data Guard environment on which it was created, whereas tape backups created on one database are considered accessible to all databases. If a backup file is not associated with any database, then the row describing it in the recovery catalog view shows null for the SITE_KEY column. By default, RMAN associates files whose SITE_KEY is null with the database to which RMAN is connected as TARGET.

In a Data Guard environment, RMAN commands can operate on any backups that are accessible. For example, assume that databases prod and standby1 reside on different hosts. RMAN backs up datafile 1 on prod to /prodhst/disk1/df1.dbf on the production host and also to tape. RMAN backs up datafile 1 on standby1 to /sby1hst/disk2/df1.dbf on the standby host and also to tape. If RMAN is connected to database prod as TARGET, then you cannot use RMAN to perform operations with the /sby1hst/disk2/df1.dbf backup located on the standby host. However, RMAN considers the tape backup made on standby1 as eligible to be restored.

Note:

You can FTP a backup from a standby host to a primary host or vice versa and then CATALOG it. After a file is cataloged by the target database, the file is associated with the target database.

As long as backups are accessible to RMAN, you can use RMAN maintenance commands such as CHANGE, CROSSCHECK, and DELETE for backups when connected to any primary or standby database.

See Also:

Oracle Data Guard Concepts and Administration to learn how to use RMAN to back up and restore files in a Data Guard environment

Syntax

backup::=

Description of backup.gif follows
Description of the illustration backup.gif

(backupOperand::=, backupSpec::=, backupSpecOperand::=)

backupOperand::=

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Description of the illustration backupoperand.gif

(deviceSpecifier::=, fileNameConversionSpec::=, formatSpec::=, forRecoveryOfSpec::=, keepOption::=, notBackedUpSpec::=, sizeSpec::=, skipSpec::=)

backupSpec::=

Description of backupspec.gif follows
Description of the illustration backupspec.gif

(archivelogRecordSpecifier::=, completedTimeSpec::=, copyOfSpec::=, datafileCopySpec::=, datafileSpec::=, backupSpecOperand::=)

backupSpecOperand::=

Description of backupspecoperand.gif follows
Description of the illustration backupspecoperand.gif

(formatSpec::=, keepOption::=, notBackedUpSpec::=, sizeSpec::=, skipSpec::=)

backupTypeSpec::=

Description of backuptypespec.gif follows
Description of the illustration backuptypespec.gif

copyOfSpec::=

Description of copyofspec.gif follows
Description of the illustration copyofspec.gif

(datafileSpec::=)

datafileCopySpec::=

Description of datafilecopyspec.gif follows
Description of the illustration datafilecopyspec.gif

duration::=

Description of duration.gif follows
Description of the illustration duration.gif

forRecoveryOfSpec::=

Description of forrecoveryofspec.gif follows
Description of the illustration forrecoveryofspec.gif

(formatSpec::=)

notBackedUpSpec::=

Description of notbackedupspec.gif follows
Description of the illustration notbackedupspec.gif

sizeSpec::=

Description of sizespec.gif follows
Description of the illustration sizespec.gif

skipSpec::=

Description of skipspec.gif follows
Description of the illustration skipspec.gif

Semantics

backup

This clause specifies the objects to be backed up as well as the options to control the backup. Refer to backup::= for the syntax diagram.

Syntax Element Description
backupOperand Specifies various options for the BACKUP command.
backupSpec Specifies one or more objects to be backed up.

Each backupSpec clause generates one or more backup sets (AS BACKUPSET) or image copies (AS COPY). For AS BACKUPSET, the backupSpec clause generates multiple backup sets if the number of datafiles specified in or implied by its list of objects exceeds the FILESPERSET limit.

   PLUS ARCHIVELOG Includes archived redo logs in the backup (see Example 2-15). Causes RMAN to perform the following steps:

Run an ALTER SYSTEM ARCHIVE LOG CURRENT statement.

Run the BACKUP ARCHIVELOG ALL command. If backup optimization is enabled, then RMAN only backs up logs that have not yet been backed up.

Back up the files specified in the BACKUP command.

Run an ALTER SYSTEM ARCHIVE LOG CURRENT statement.

Back up any remaining archived redo logs. If backup optimization is not enabled, then RMAN backs up the logs generated in step 1 plus all the logs generated during the backup.

Note: You cannot specify PLUS ARCHIVELOG on the BACKUP ARCHIVELOG command or BACKUP AS COPY INCREMENTAL command (or BACKUP INCREMENTAL command when the default backup type is COPY). You cannot specify PLUS ARCHIVELOG when also specifying INCREMENTAL FROM SCN.

Note: Unless the online redo log is archived at the end of the backup, DUPLICATE will not be possible with this backup.

    backupSpecOperand Specifies a variety of options and parameters that affect the backupSpec clause.

backupOperand

This subclause specifies options such as the device type and output format. Refer to backupOperand::= for the syntax diagram.

Syntax Element Description
backupTypeSpec Specifies the type of backup being created, either backup sets (AS BACKUPSET) or image copies (AS COPY).

See Also: backupTypeSpec for details

CHANNEL channel_id Specifies the case-sensitive name of a channel to use when creating backups. Use any meaningful name, for example ch1 or dev1. The database uses the channel ID to report I/O errors. If you do not set this parameter, then RMAN dynamically assigns the backup sets to any available channels during execution.

As shown in Example 2-23, you can use CHANNEL to specify which channels back up which files.

Note: You can also specify this parameter in the backupSpec clause.

CHECK LOGICAL Tests data and index blocks that pass physical corruption checks for logical corruption (see Example 2-25). This option typically adds 1-3% overhead.

Examples of logical corruption are corruption of a row piece or index entry. If RMAN finds logical corruption, then it logs the block in the alert log and server session trace file. The SET MAXCORRUPT command specifies the total number of physical and logical corruptions permitted in a datafile.

By default, the BACKUP command computes a checksum for each block and stores it in the backup. If you specify the NOCHECKSUM option, then RMAN does not perform a checksum of the blocks when writing the backup.

If SET MAXCORRUPT and NOCHECKSUM are not set, then CHECK LOGICAL detects all types of corruption that are possible to detect during a backup.

COPIES integer Sets the number of identical backups (1 - 4) that RMAN creates. The default value is 1.

You can use multiple format strings to specify different names and locations for the copies. Example 2-22 illustrates a duplexed backup to different locations on disk.

RMAN can duplex backups to either disk or tape, but cannot duplex backups to tape and disk simultaneously. When backing up to tape, ensure that the number of copies does not exceed the number of available tape devices. Also, if COPIES is greater than 1, then the BACKUP_TAPE_IO_SLAVES initialization parameter must be enabled on the target database.

You can specify duplexing on more than one command. The order of precedence is as follows, with settings higher on the list overriding lower settings:

BACKUP COPIES

SET BACKUP COPIES

CONFIGURE ... BACKUP COPIES

Note: This option does not apply with AS COPY and results in an error message.

Note: Duplexing cannot be used when creating files in the flash recovery area.

CUMULATIVE Copies the data blocks used since the most recent level 0 backup (see Example 2-16).

Note: This option does not apply with AS COPY and results in an error message.

DEVICE TYPE deviceSpecifier Allocates automatic channels for the specified device type only. For example, if you configure disk and tape channels, then configure sbt as the default device type, then the following command allocates disk channels only:
BACKUP DEVICE TYPE DISK DATABASE;

The DEVICE TYPE option is valid only for automatic channels and is not valid for manually allocated channels. You cannot use the DEVICE TYPE option for a device other than DISK if you have not already run CONFIGURE DEVICE TYPE for this device.

Note: You cannot specify DEVICE TYPE DISK when running the BACKUP RECOVERY AREA command.

See Also: deviceSpecifier

DISKRATIO integer Directs RMAN to populate each backup set with datafiles from at least integer disks.

This parameter is only enabled when you are backing up datafiles or control files, and when the operating system can give RMAN disk contention and node affinity data. To manually disable this feature, set DISKRATIO to 0.

For example, assume that datafiles are distributed across 10 disks. If the disks supply data at 10 bytes/second, and if the tape drive requires 50 bytes/second to keep streaming, then set DISKRATIO to 5 to direct RMAN to include datafiles from at least 5 disks in each backup set.

If you set FILESPERSET but not DISKRATIO, then DISKRATIO defaults to the same value as FILESPERSET. If you specify neither parameter, then DISKRATIO defaults to 4. RMAN compares the DISKRATIO value to the actual number of devices involved in the backup and uses the lowest value. For example, if DISKRATIO is 4 and the datafiles are located on three disks, then RMAN attempts to include datafiles from three disks in each backup set.

The DISKRATIO parameter is easier for datafile backups when the datafiles are striped or reside on separate disk spindles and you either:

  • Use a high-bandwidth tape drive that requires several datafiles to be multiplexed in order to keep the tape drive streaming

  • Make backups while the database is open and you need to spread the I/O load across several disk spindles to leave bandwidth for online operations.

Note: Do not spread I/O over more than the minimum number of disks required to keep the tape streaming. Otherwise, you increase restore time for a file without increasing performance.

duration Specifies options related to the maximum time for a backup command to run.

See Also: duration

fileNameConversionSpec This option is valid only when BACKUP is creating image copies. Files being copied are renamed according to the specified patterns. If a file being backed up has a name that does not match any of the specified rename patterns, then RMAN uses FORMAT to name the output image copies. If no FORMAT is specified, then RMAN uses the default format %U.

See Also: fileNameConversionSpec for file renaming patterns

FILESPERSET integer Specifies the maximum number of input files to include in each output backup set. This parameter is only relevant when BACKUP generates backup sets.

RMAN backs up the files in each backupSpec as one or more backup sets. When the number of files in each backupSpec exceeds the FILESPERSET setting, then RMAN splits the files into multiple backup sets accordingly. The default value for FILESPERSET is 64.

The RMAN behavior is illustrated by the following BACKUP commands:

BACKUP AS BACKUPSET (DATAFILE 3, 4, 5, 6, 7) (DATAFILE 8, 9);
BACKUP AS BACKUPSET DATAFILE 3, 4, 5, 6, 7, 8, 9;
BACKUP AS BACKUPSET DATAFILE 3, ... 72;

In the first command, RMAN places datafiles 3, 4, 5, 6, and 7 into one backup set and datafiles 8 and 9 into another backup set. In the second command, RMAN places all datafiles into one backup set. In the third command, the ellipses indicate datafiles 3 through 72. Because in this case RMAN is backing up 70 datafiles, RMAN places 64 files in one backup set and 6 in another.

By default, RMAN divides files among backup sets in order to make optimal use of channel resources. The number of files to be backed up is divided by the number of channels. If the result is less than 64, then this number is the FILESPERSET value. Otherwise, FILESPERSET defaults to 64.

Note: You cannot specify the number of backup pieces that should be in a backup set.

FORCE Forces RMAN to ignore backup optimization. That is, even if CONFIGURE BACKUP OPTIMIZATION is set to ON, RMAN backs up all specified files and undo data for active transactions.

Note: You can also specify this option in the backupSpecOperand clause.

AUXILIARY FORMAT Copies the files on the target database to the specified location on the auxiliary instance. RMAN can only generate image copies when AUXILIARY FORMAT is specified. RMAN must be connected to both TARGET and AUXILIARY instances and have access to auxiliary channels.

You can use the BACKUP AUXILIARY FORMAT command to copy datafiles over the network between primary and standby databases. For example, if a datafile on a primary database was lost, you could CONNECT to the standby database as TARGET and the primary database as AUXILIARY, and copy an intact datafile from the standby host to the primary host.

   formatSpec Specifies a pattern for naming the output image copies on an auxiliary instance. The path must be valid on the auxiliary host.

See Also: formatSpec for valid substitution variables

   NEW Creates an image copy in the directory specified in the DB_CREATE_FILE_DEST initialization parameter of the auxiliary instance. The image copy is an Oracle-managed file.
FORMAT formatSpec Specifies a pattern for naming the output backup pieces or image copies (see Example 2-17). For AS COPY, if one or more of the directories mentioned in the specified format does not exist, then RMAN signals an error.

The default location for disk backups depends on whether a flash recovery area is enabled and whether FORMAT is specified:

  • If a flash recovery area is enabled, and if you do specify FORMAT, then RMAN names the output files according to the FORMAT setting. If no location is specified in FORMAT, then RMAN creates the backup in a platform-specific location—not in the recovery area.

  • If a flash recovery area is enabled, and if you do not specify FORMAT, then RMAN creates the backup in the recovery area and uses the substitution variable %U to name the backup.

  • If a flash recovery area is not enabled, and if you do not specify FORMAT, then RMAN creates the backup in a platform-specific location and uses %U to name the backup.

To create RMAN backups in the flash recovery area with names in Oracle Managed Files format, do not specify the FORMAT clause on the BACKUP command or channel.

Note: You cannot specify an Oracle Managed Files filename as the format for a backup. For example, if +DISK1/datafile/system.732.609791431 is an OMF filename, then you cannot specify this filename in the FORMAT parameter.

Backup pieces must have unique names. The maximum length of a backup piece filename is platform-specific. For backups to a media manager, the length is also limited by the limit in the supported version of the media management API. Vendors supporting SBT 1.1 must support filenames up to 14 characters. Some SBT 1.1 vendors may support longer filenames. Vendors supporting SBT 2.0 must support filenames up to 512 characters. Some SBT 2.0 vendors may support longer filenames.

You cannot specify multiple, identical FORMAT strings within a single backupSpec (for example, BACKUP DATAFILE 3 TO '/tmp/df3.f', DATAFILE 4 TO '/tmp/df4.f'). However, RMAN permits a single FORMAT string to exist in multiple backupSpec clauses.

Note: If you are making an archival backup with the KEEP option (see Example 2-26), then the format string must contain %U. The autobackup also uses this format string.

See Also: formatSpec for valid substitution variables

forRecoveryOfSpec Identifies the backup being created as an incremental backup to be used in rolling forward an image copy.

See Also: forRecoveryOfSpec

FULL Creates a backup of all blocks of datafiles included in the backup. FULL is the opposite of INCREMENTAL. RMAN makes full backups by default if neither FULL nor INCREMENTAL is specified.

A full backup has no effect on subsequent incremental backups and is not considered a part of any incremental backup strategy. A full image copy backup can be incrementally updated, however, by applying incremental backups with the RECOVER command.

Note: Unused block compression, which is described in the entry for BACKUP AS BACKUPSET, causes some datafile blocks to be skipped during full backups.

INCREMENTAL LEVEL integer Copies only those data blocks that have changed since the last incremental integer backup, where integer is 0 or 1 (see Example 2-16).

See "Incremental Backups" for an explanation of incremental backups.

INCREMENTAL FROM SCN integer Creates an incremental backup of all specified datafiles that includes all datafile blocks changed at SCNs greater than or equal to the specified SCN.

One use of this option is to refresh a standby database with changes from the primary database (see Example 2-24, and the chapter on RMAN backups in Oracle Data Guard Concepts and Administration). This backup contains all changed blocks since the standby database was created or last synchronized. At the standby database, you can use RECOVER with NOREDO to apply the incremental backup. All changed blocks captured in the incremental backup are applied at the standby database, bringing it current with the primary database.

If you are not making incremental backups based on Volume Shadow Copy Service (VSS) snapshots, then you should specify formatSpec when you specify INCREMENTAL FROM SCN. The FORMAT string should include substitution variables such as %U because RMAN generates a control file backup.

If you specify FROM SCN with the NOKEEP option, and if you do not specify formatSpec when you specify INCREMENTAL FROM SCN, then RMAN creates incremental backups in the flash recovery area so that you can create incremental backups based on VSS snapshots in a Windows environment. In this way, you can use incremental backup sets and VSS shadow copies in conjunction. The checkpoint SCN value specified in the FROM SCN parameter should be same as the BACKUP_CHECKPOINT value in the VSS backup metadata document. If block change tracking is enabled, then the backups will use the change tracking mechanism, which significantly reduces the time taken to create incremental backups. RMAN can apply incremental backups from the flash recovery area during recovery transparently.

Note: You cannot use PLUS ARCHIVELOG when also specifying INCREMENTAL FROM SCN.

See Also: Oracle Database Platform Guide for Microsoft Windows to learn about making backups with VSS

keepOption Overrides any configured retention policy for this backup so that the backup is not considered obsolete, as shown in Example 2-26.

You can use the KEEP syntax to generate archival database backups that satisfy business or legal requirements. The KEEP setting is an attribute of the backup set (not individual backup piece) or image copy.

Note: You cannot use KEEP with BACKUP BACKUPSET.

With the KEEP syntax, you can keep the backups so that they are considered obsolete after a specified time (KEEP UNTIL), or make them never obsolete (KEEP FOREVER). As shown in Example 2-27, you must be connected to a recovery catalog when you specify KEEP FOREVER.

Note: You can use CHANGE to alter the status of a backup generated with KEEP.

See Also: keepOption for more information about backups made with the KEEP option

MAXSETSIZE sizeSpec Specifies a maximum size for a backup set (as shown in Example 2-17). RMAN limits all backup sets to this size.

It is possible for a backup set to span multiple tapes, so blocks from each datafile are written to multiple tapes. If one tape of a multivolume backup set fails, then you lose the data on all the tapes rather than just one. Because a backup set always include a whole file rather than part of a file, you can use MAXSETSIZE to specify that each backup set should fit on one tape.

Specify size in bytes (default), kilobytes (K), megabytes (M), or gigabytes (G). For example, to limit a backup set to 3 MB, specify MAXSETSIZE 3M. The default size is in bytes, rounded down from kilobytes. For example, MAXSETSIZE 3000 is rounded down to 2 KB (2048 bytes). The minimum value must be greater than or equal to the database block size.

The default number of files in each backup set is determined by FILESPERSET, which defaults to 64. When you specify MAXSETSIZE, RMAN attempts to limit the size in bytes of the backup sets according to the MAXSETSIZE parameter. The limit on the number of files in a backup set will apply even if the total size of the resulting backup set is less than MAXSETSIZE.

Note: This option results in an error message if used with BACKUP AS COPY. If you run BACKUP AS COPY on a channel that has MAXSETSIZE set, then MAXSETSIZE is silently ignored.

notBackedUpSpec Limits the set of archived redo log files to be backed up according to whether a specified number of backups are already present (and not obsolete), or whether the logs have been backed up since a specified date.

See Also: notBackedUpSpec

NOCHECKSUM Suppresses block checksums during the backup.

A checksum is a number that is computed from the contents of a data block. DB_BLOCK_CHECKSUM is a database initialization parameter that controls the writing of checksums for the blocks in datafiles in the database (not backups). If DB_BLOCK_CHECKSUM is typical, then the database computes a checksum for each block during normal operations and stores it in the block before writing it to disk. When the database reads the block from disk later, it recomputes the checksum and compares it to the stored value. If they do not match, then the block is damaged.

Note: You cannot disable checksums for datafiles in the SYSTEM tablespace even if DB_BLOCK_CHECKSUM=false.

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 datafiles 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.

When restoring a backup datafile, RMAN honors the DB_BLOCK_CHECKSUM initialization parameter setting. RMAN clears the checksum if DB_BLOCK_CHECKSUM is set to false. If set to typical, then RMAN verifies the checksum when restoring from the backup and writing to the datafile.

Note: You can turn off checksum checking by specifying NOCHECKSUM, but other physical consistency checks, such as checks of the block headers and footers, cannot be disabled.

See Also: Oracle Database Reference for more information about the DB_BLOCK_CHECKSUM initialization parameter

NOEXCLUDE When specified on a BACKUP DATABASE or BACKUP COPY OF DATABASE command, RMAN backs up all tablespaces, including any for which a CONFIGURE EXCLUDE command has been entered. This option does not override SKIP OFFLINE or SKIP READONLY.
POOL integer Specifies the media pool in which the backup should be stored. Consult your media management documentation to see whether POOL is supported.

Note: This option does not work with AS COPY and results in an error.

PROXY Backs up the specified files by means of the proxy copy functionality, which gives the media management software control over the data transfer between storage devices and the datafiles on disk. The media manager—not RMAN—decides how and when to move data.

When you run BACKUP with the PROXY option, RMAN performs these steps:

Searches for a channel of the specified device type that is proxy-capable. If no such channel is found, then RMAN issues a warning and attempts a a conventional (that is, non-proxy) backup of the specified files.

If RMAN locates a proxy-capable channel, then it calls the media manager to check if it can proxy copy the files. If the media manager cannot proxy copy, then RMAN uses conventional backup sets to back up the files.

Note: If you specify PROXY, then the %p variable must be included in the FORMAT string either explicitly or implicitly within %U.

Note: This option does not work with AS COPY and results in an error.

   ONLY Causes the database to issue an error message when it cannot proxy copy rather than creating conventional backup sets. If you do not want RMAN to try a conventional copy when a proxy copy fails, use the ONLY option
REUSE Enables RMAN to overwrite an already existing backup or copy with the same filename as the file that BACKUP is currently creating.
SECTION SIZE sizeSpec Specifies the size of each backup section produced during a datafile or datafile copy backup.

By setting this parameter, RMAN can create a multisection backup. In a multisection backup, RMAN creates a backup piece that contains one file section, which is a contiguous range of blocks in a file. All sections of a multisection backup are the same size.

File sections enable RMAN to create multiple steps for the backup of a single large datafile. RMAN channels can process each step independently and in parallel, with each channel producing one section of a multisection backup set.

If you specify a section size that is larger than the size of the file, then RMAN does not use multisection backup for the file. If you specify a small section size that would produce more than 256 sections, then RMAN increases the section size to a value that results in exactly 256 sections.

Note: Depending on where you specify this parameter in the RMAN syntax, you can specify different section sizes for different files in the same backup job.

Note: You cannot use SECTION SIZE in conjunction with MAXPIECESIZE.

skipSpec Excludes datafiles or archived redo logs from the backup if they are inaccessible, offline, or read-only.

See Also: skipSpec for details.

TAG tag_name Specifies a user-specified tag name for a backup set, proxy copy, datafile copy, or control file copy. The tag is applied to the output files generated by the BACKUP command.

The tag name is not case-sensitive. The name must be 30 characters or less. The characters are limited to the characters that are valid in filenames on the target file system. For example, ASM does not support the use of the hyphen (-) character in the filenames it uses internally, so weekly-incremental is not a valid tag name for backups in ASM disk groups. Environment variables are not valid in the TAG parameter.

Typically, a tag name is a meaningful name such as MON_PM_BKUP or WEEKLY_FULL_BKUP. Tags are reusable, so that backup set 100 can have the tag MON_PM_BKUP one week while backup set 105 has the same tag the next week.

If you do not specify a tag name, then by default RMAN creates a tag for backups (except for control file autobackups). The default tag uses the format TAGYYYYMMDDTHHMMSS, where YYYY is the year, MM is the month, DD is the day, HH is the hour (in 24-hour format), MM is the minutes, and SS is the seconds. For example, a backup of datafile 1 might receive the tag TAG20070208T133437. The date and time refer to when RMAN started the backup. If multiple backup sets are created by one BACKUP AS BACKUPSET command, then each backup piece is assigned the same default tag.

You can also specify the tag at the backupSpec level. If you specify the tag at:

  • The command level, then all backup sets created by the command have the tag.

  • The backupSpec level, then backup sets created as a result of different backup specifications can have different tags.

  • Both levels, then the tag in the backupSpec takes precedence.

Note: A tag is an attribute of each backup piece in a given copy of a backup set (for AS BACKUPSET) or each image copy (for AS COPY). For example, if you run BACKUP AS BACKUPSET COPIES 1 DATABASE TAG TUE_PM, then only one copy of the backup set exists and each backup piece has tag TUE_PM. Assume that this backup set has primary key 1234. If you then run BACKUP BACKUPSET 1234 TAG WED_PM, then the first copy of the backup set has tag TUE_PM and the second copy of the backup set has tag WED_PM.

VALIDATE Scans the specified files and verifies their contents, testing whether this file can be backed up and whether the data blocks are corrupt.

RMAN creates no output files. This option is equivalent to using the VALIDATE command on the database files specified in the backup.

If you do not specify CHECK LOGICAL, then BACKUP VALIDATE checks for physical corruption only. If you specify CHECK LOGICAL, then BACKUP VALIDATE checks for both physical and logical corruption. RMAN populates the V$DATABASE_BLOCK_CORRUPTION view with any corruptions that it finds.

You can use the SET MAXCORRUPT command to set a limit for the number of corrupt blocks tolerated during the backup validation. The default is zero.

If you execute BACKUP INCREMENTAL with VALIDATE, then the behavior depends on whether block change tracking is enabled. If change tracking is enabled, then RMAN validates only changed blocks; otherwise, RMAN validates all blocks in the files included in the backup.

Note: You cannot validate backups of backup sets.


backupSpec

This subclause specifies a list of one or more objects to be backed up. Each backupSpec clause generates one or more backup sets (AS BACKUPSET) or image copies (AS COPY). For AS BACKUPSET, the backupSpec clause generates multiple backup sets if the number of datafiles specified in or implied by its list of objects exceeds the default limit of 4 datafiles or 16 archived logs in each backup set. Refer to backupSpec::= for the syntax diagram.

Syntax Element Description
archivelogRecordSpecifier Specifies a range of archived redo logs to be backed up.

When backing up archived redo logs, RMAN can perform archived log failover automatically. RMAN backs up the log when at least one archived log corresponding to a given log sequence number and thread is available. Also, if the copy that RMAN is backing up contains corrupt blocks, then it searches for good copies of these blocks in other copies of the same archived logs.

RMAN does not signal an error if the command finds no logs to back up, since this situation probably exists because no new logs were generated after the previous BACKUP ARCHIVELOG ALL DELETE INPUT command. The only exception to this behavior is when the SEQUENCE number clause is specified. In this scenario, RMAN signals the RMAN-06004 error if an archived redo log file of the specified sequence is not found.

If you specify BACKUP ARCHIVELOG ALL, then RMAN backs up exactly one copy of each distinct log sequence number. For example, if you archive to multiple destinations, RMAN backs up one copy of each log sequence number—not each copy of each log sequence number. For other commands, such as DELETE ALL does refer to every log, even duplicate log sequences.

If the database is open when you run BACKUP ARCHIVELOG, and if the UNTIL clause or SEQUENCE parameter is not specified, then RMAN runs ALTER SYSTEM ARCHIVE LOG CURRENT.

Note: If you run BACKUP ARCHIVELOG ALL, or if the specified log range includes logs from prior incarnations, then RMAN backs up logs from prior incarnations to ensure availability of all logs that may be required for recovery through an OPEN RESETLOGS.

See Also: archivelogRecordSpecifier for syntax, and Oracle Database Backup and Recovery User's Guide explanations of backup failover for logs and automatic log switching

BACKUPSET Specifies a backup of backup sets. Use this parameter in conjunction with the DEVICE TYPE sbt clause to offload backups on disk to tape (as shown in Example 2-21). You cannot back up from tape to tape or from tape to disk: only from disk to disk or disk to tape.

If you specify the DELETE INPUT option on the BACKUP BACKUPSET command, then RMAN deletes all copies of the backup set that exist on disk. For example, if you duplexed a backup to 4 locations, then RMAN deletes all 4 backup sets. The ALL option does not add any functionality.

RMAN performs backup set failover when backing up backup sets. RMAN searches for all available backup copies when the copy that it is trying to back up is corrupted or missing. This behavior is similar to RMAN's behavior when backing up archived logs that exist in multiple archiving destinations.

If backup optimization is enabled when you back up a backup set, and if the identical backup set has already been backed up to the same device type, then RMAN skips the backup of this backup set.

Note: You can duplex backups of backup sets with BACKUP COPIES and SET BACKUP COPIES.

Note: When you use BACKUP BACKUPSET command with encrypted backup sets, the backup sets are backed up in their encrypted form. Because BACKUP BACKUPSET just copies an already-encrypted backup set to disk or tape, no decryption key is needed during a BACKUP BACKUPSET operation. The data is never decrypted during any part of the operation. The BACKUP BACKUPSET command can neither encrypt nor decrypt backup sets.

   ALL Specifies all backup sets.
   completedTimeSpec Identifies backup sets according to completion time.

See Also: completedTimeSpec

   integer Specifies backup sets according to primary key. You can obtain the primary keys for backup sets from the output of the LIST BACKUP command.
CONTROLFILECOPY Specifies one or more control file copies for backups.

A control file copy can be created with the BACKUP AS COPY CURRENT CONTROLFILE command or the SQL statement ALTER DATABASE BACKUP CONTROLFILE TO '...'.

Note: A control file autobackup is not a control file copy.

   'filename' Specifies a control file copy by filename.
   ALL Specifies all control file copies.
   LIKE 'string_pattern' Specifies a control file copy by a filename pattern. The percent sign (%) as a wildcard meaning 0 o r more characters; an underscore (_) is a wildcard meaning 1 character.
copyOfSpec Makes a backup of previous image copies of datafiles and possibly control files.

See Also: copyOfSpec

CURRENT CONTROLFILE Specifies the current control file.
DATABASE Creates a backup of all datafiles in the database. If generating a backup set, then RMAN can include only datafiles and control files: it cannot include archived redo logs.

If the backupSpec includes datafile 1, and if CONFIGURE CONTROLFILE AUTOBACKUP is OFF, then RMAN automatically includes the control file in the backup. If the instance is started with a server parameter file, then RMAN also includes this parameter file in the backup.

If the backupSpec includes datafile 1, and if CONFIGURE CONTROLFILE AUTOBACKUP is ON, then RMAN does not automatically include the control file in the output. Instead, RMAN generates a separate control file autobackup piece. If the instance is started with a server parameter file, then RMAN includes this parameter file in the autobackup piece.

Full database backups should usually be either image copies or compressed backup sets. Image copies are more flexible than backup sets for some purposes (such as use in an incrementally updated backups strategy), and compressed backup sets make more efficient use of storage space, if the CPU overhead involved in creating them is tolerable.

Note: To force RMAN to include the current control file in the backup when CONTROLFILE AUTOBACKUP is ON, specify the INCLUDE CURRENT CONTROLFILE clause.

See Also: The TABLESPACE description to learn about backup behavior when the database includes bigfile tablespaces

datafileCopySpec Specifies the filenames of one or more datafile image copies.

See Also: datafileCopySpec for details

DATAFILE datafileSpec Specifies a list of one or more datafiles. Refer to description of BACKUP DATABASE for RMAN behavior when datafile 1 is backed up.

See Also: datafileSpec

RECOVERY AREA Backs up recovery files created in the current and all previous flash recovery area destinations. The backup must go to SBT.

Recovery files are full and incremental backup sets, control file autobackups, datafile copies, and archived redo logs. If an archived redo log file is missing or corrupted, then RMAN looks outside of the recovery area for a good copy of the log that it can use for the backup. Flashback logs, the current control file, and online redo logs are not backed up.

By default, backup optimization is enabled for this command even if the CONFIGURE BACKUP OPTIMIZATION setting is OFF. You can disable backup optimization for BACKUP RECOVERY AREA by specifying FORCE.

Note: If the flash recovery area is not enabled but has been enabled in the past, then files created in the previous flash recovery area location are backed up.

DB_RECOVERY_FILE_DEST RECOVERY AREA and DB_RECOVERY_FILE_DEST are synonyms.
RECOVERY FILES Backs up all recovery files on disk, whether they are stored in the flash recovery area or other locations on disk. The backup must go to SBT.

Recovery files include full and incremental backup sets, control file autobackups, archived redo log files, and datafile copies.

By default, backup optimization is enabled for this command even if the CONFIGURE BACKUP OPTIMIZATION setting is OFF. You can disable backup optimization for RECOVERY FILES by specifying FORCE.

SPFILE Specifies that the server parameter file should be included in a backup set. The AS COPY option is not supported for server parameter file backups.

RMAN backs up the server parameter file currently in use by the target database. RMAN cannot back up the server parameter file when the instance was started with an initialization parameter file. RMAN cannot make incremental backups of the SPFILE.


TABLESPACE
tablespace_name
Specifies the names of one or more tablespaces. RMAN translates tablespace names internally into a list of datafiles, then backs up all datafiles that are currently part of the tablespaces. If the SYSTEM tablespace (and thus datafile 1) is included in the backup, and if CONTROLFILE AUTOBACKUP is not configured, then RMAN also creates a copy of the control file.

You cannot back up locally-managed temporary tablespaces, although you can back up dictionary-managed tablespaces.

If the following conditions are met, then RMAN can back up transportable tablespaces that have not been made read/write after being transported:

  • The COMPATIBLE initialization parameter is set to 11.0.0 or higher.

  • You are using an Oracle Database 11g RMAN client.

If any of the preceding conditions is not met, then RMAN automatically skips transportable tablespaces that have not yet been made read/write. Note that if you specify a transportable tablespace explicitly when any of the conditions is not met, then RMAN issues an error saying that the tablespace does not exist.

Note: If you rename a tablespace, then RMAN detects that the tablespace has changed its name and updates the recovery catalog on the next resynchronization.

backupSpecOperand The backupSpecOperand that follows a backupSpec specifies options that apply to the backupSpec.

backupSpecOperand

This subclause specifies a variety of options and parameters that affect the backupSpec clause. Many subclauses are also used with backupOperand. Options that are not shared in common with backupOperand are listed here. Refer to backupSpecOperand::= for the syntax diagram.

Syntax Element Description
DELETE [ALL] INPUT Deletes the input files after successfully backing them up.

Specify this option only when backing up archived redo logs, datafile copies (COPY OF or DATAFILECOPY), or backup sets. The BACKUP ARCHIVELOG command only backs up one copy of each distinct log sequence number, so if the DELETE INPUT option is used without the ALL keyword, RMAN only deletes the copy of the file that it backs up.

Specifying the DELETE INPUT option is equivalent to issuing the DELETE command for the input files. When backing up archived redo logs, RMAN uses the configured settings to determine whether an archived redo log can be deleted (CONFIGURE ARCHIVELOG DELETION POLICY TO BACKED UP).

The ALL option applies only to archived redo logs. If you run DELETE ALL INPUT, then the command deletes all copies of corresponding archived redo logs or datafile copies that match the selection criteria in the BACKUP command (as shown in Example 2-19). For example, if you specify the SEQUENCE n clause, then RMAN deletes all archived redo logs with same sequence number n.

Note: The database retains archived redo logs in the flash recovery as long as possible and deletes them automatically when additional disk space is required. You can use the BACKUP DELETE INPUT, DELETE ARCHIVELOG, and DELETE OBSOLETE commands to delete logs manually from locations inside or outside the recovery area. You do not need to specify BACKUP DELETE INPUT when backing up the recovery area because the database automatically deletes logs based on the archived log deletion policy and other flash recovery area rules.

FROM TAG tag_name Identifies files by tag name (see Example 2-18). Defined in context with several other commands.
INCLUDE CURRENT CONTROLFILE Creates a snapshot of the current control file and places it into one of backup sets produced by the BACKUP command.

Note: This option does not apply with AS COPY and results in an error message.


backupTypeSpec

This subclause specifies the form of the BACKUP command output: backup set or image copy. Refer to backupTypeSpec::= for the syntax diagram.

Syntax Element Description
AS BACKUPSET Creates backup sets on the specified device. This is the default backup type.

AS BACKUPSET is the only possibility when backing up to tape, and for creating level 1 incremental backups to any destination. Backup sets are RMAN-specific logical structures. The backup set is the smallest unit of a backup.

The FILESPERSET parameter of the BACKUP command determines the maximum number of files in each backup set. Archived logs and datafiles are never combined into a single backup set.

When using encrypted backups (see "Encryption of Backup Sets"), datafiles from tablespaces with different encryption settings are never written into the same backup set.

RMAN cannot back up files with different block sizes into the same backup set. RMAN can back up tablespaces with different block sizes, but puts each differently sized datafile into its own backup set.

RMAN backup sets automatically use unused block compression. Skipping unused data blocks where possible enables RMAN to back up datafiles using less space, and can make I/O more efficient. When backing up datafiles into backup sets, RMAN does not include data blocks that have never been allocated. RMAN also skips datafile blocks that do not currently contain data, but only if all of the following conditions apply:

  • The COMPATIBLE initialization parameter is set to 10.2 or higher.

    Note that if COMPATIBLE is 10.2, then only tablespaces created with 10.2 compatibility will be optimized to exclude blocks that do not currently contain data. If COMPATIBLE is 11.0.0 or higher, however, then the first backup that produces backup sets after COMPATIBLE is set to 11.0.0 or higher will update the headers of all locally managed datafiles so that all locally managed datafiles can be optimized.

  • There are currently no guaranteed restore points defined for the database.

  • The datafile is locally managed.

  • The datafile is being backed up to a backup set as part of a full backup or a level 0 incremental backup.

  • The backup set is created on disk or Oracle Secure Backup is the media manager. Thus, when backing up to a media manager other than Oracle Secure Backup, RMAN does not skip datafile blocks that do not currently contain data.

Note: If RMAN does not read a block because of unused block compression, and if the block is corrupt, then RMAN does not detect the corruption. A corrupt unused block is not harmful.

Each backup set contains at least one backup piece, which is an RMAN-specific physical file containing the backed up data. You can also use the BACKUP command to generate a proxy copy, which is a backup in which the entire data transfer is conducted by a media manager.

RMAN only records complete backup sets in the RMAN repository. There are no partial backup sets. When a BACKUP command creates backup pieces but does not produce a complete backup set, the backup pieces are discarded.

Note: You cannot stripe a single backup set across multiple channels. You also cannot stripe a single input file across multiple backup sets.

See Also: Oracle Secure Backup Administrator's Guide to learn how to use Oracle Secure Backup with RMAN

   COMPRESSED Enables binary compression.

RMAN compresses the data written into the backup set to reduce the overall size of the backup set. All backups that create backup sets can create compressed backup sets. Restoring compressed backup sets is no different from restoring uncompressed backup sets.

RMAN applies a binary compression algorithm as it writes data to backup sets. This compression is similar to the compression provided by many media manager vendors. When backing up to a locally attached tape device, compression provided by the media management vendor is usually preferable to the binary compression provided by BACKUP AS COMPRESSED BACKUPSET. Therefore, use uncompressed backup sets and turn on the compression provided by the media management vendor when backing up to locally attached tape devices. You should not use RMAN binary compression and media manager compression together.

Some CPU overhead is associated with compressing backup sets. If the target database is running at or near its maximum load, then you may find the overhead unacceptable. In most other circumstances, compressing backup sets saves enough disk space to be worth the CPU overhead.

AS COPY Creates image copies (rather than backup sets).

An image copy is a byte-for-byte identical copy of the original file. You can create image copy backups of datafiles, datafile copies, and archived redo log files. Image copy files can only exist on disk.When using incrementally updated backups, the level 0 incremental must be an image copy backup.

By default, BACKUP generates backup sets. You can change the default backup type for disk backups to image copies using the CONFIGURE DEVICE TYPE ... BACKUP TYPE TO COPY command.

RMAN chooses a location for the copy according to the following rules, listed in order of precedence:

FORMAT specified on BACKUP command for the object being backed up

FORMAT specified for the BACKUP command

fileNameConversionSpec setting for BACKUP command

CONFIGURE CHANNEL integer ... FORMAT

CONFIGURE CHANNEL DEVICE TYPE ... FORMAT

Platform-specific default FORMAT (which includes a %U for generating a unique filename)

You can create and restore image copy backups with RMAN or use a native operating system command for copying files. When you use RMAN, copies are recorded in the RMAN repository and are more easily available for use in restore and recovery. Otherwise, you must use the CATALOG command to add the user-managed copies to the RMAN repository so that RMAN can use them.

You cannot make a copy of a backup set, although you can make an image copy of an image copy. To back up a backup set, use BACKUP BACKUPSET.


copyOfSpec

This subclause specifies the form of the BACKUP command output: backup set or image copy. Refer to copyOfSpec::= for the syntax diagram.

Syntax Element Description
COPY OF DATABASE Makes a backup of previous image copies of all datafiles and control files in the database. All datafiles that would normally be included by BACKUP DATABASE are expected to have copies: if not, RMAN signals an error. It is not necessary for all copies to have been produced by a single BACKUP command. If multiple copies exist of datafile, then RMAN backs up the latest. Optionally, specify the copies by tag name (for example, FULL_COLD_COPY).

Note: The output of this command can be image copies or backup sets.

COPY OF DATAFILE datafileSpec Makes a backup of a previous image copy of one or more datafiles. Specify the datafile by file number (DATAFILE 3) or filename (DATAFILE '?/oradata/trgt/users01.dbf'). You specify the datafile filename and not the filename of the copy of the datafile. If more than one copy exists of a given datafile, then RMAN backs up the most recent copy.

Note: It is not necessary for the image copies that you are backing up to have been created by a single BACKUP command.

Note: The output of this command can be image copies or backup sets.

See Also: datafileSpec

COPY OF TABLESPACE tablespace_name Makes a backup of previous image copies of the datafiles in one or more specified tablespaces. All datafiles that would normally be included by BACKUP TABLESPACE should have copies: if not, then RMAN signals an error. It is not necessary for all copies to have been produced by a single BACKUP command. If multiple copies exist of datafile, then RMAN backs up the latest.

Specify the tablespaces in the list by tablespace name (for example, users) or specify a particular copy by tag name (for example, 0403_CPY_OF_USERS). If you do not specify TAG, then RMAN backs up the most recent datafile copy for each datafile in the tablespace.

Note: The output of this command can be image copies or backup sets.


datafileCopySpec

This subclause specifies datafile copies. Refer to datafileCopySpec::= for the syntax diagram.

Syntax Element Description
'filename' Specifies the filenames of one or more datafile image copies.
ALL Specifies that all datafile image copies should be backed up.
LIKE 'string_pattern' Specifies a filename pattern. The percent sign (%) is a wildcard that means zero or more characters; an underscore (_) is a wildcard that means one character.
FROM TAG tag_name Specifies a list of one or more datafile copies, identified by the tag name. If multiple datafile copies with this tag exist, then RMAN backs up only the most current datafile copy of any particular datafile. Tags are not case sensitive.
   NODUPLICATES Prevents the inclusion of identical datafile copies in a backup operation (Example 2-29). For each set of duplicate datafile copies, the file with the most recent timestamp will be selected.

duration

This subclause specifies datafile copies. Refer to duration::= for the syntax diagram.

Syntax Element Description
DURATION hh:mm Specifies a maximum time for a backup command to run. If a backup command does not complete in the specified duration, then the backup stops.

Without the PARTIAL option, the backup command is considered to have failed if it does not complete in the specified duration, and RMAN reports an error. If the backup command is part of a RUN block, then subsequent commands in the RUN block do not execute.


   MINIMIZE
   {LOAD | TIME}
With disk backups, you can use MINIMIZE TIME run the backup at maximum speed (default), or MINIMIZE LOAD to slow the rate of backup to lessen the load on the system. With MINIMIZE LOAD the backup will take the full specified duration.

If you specify TIME, then file most recently backed up is given the lowest priority to back up. This scheduling mechanism provides for the eventual complete backup of the database during successive backup windows, as different datafiles are backed up in round-robin fashion.

   PARTIAL With the PARTIAL option, the command is considered to have completed successfully and no error is reported by RMAN even if the whole backup is not completed in the specified duration.

Without the PARTIAL option, the backup command is considered to have failed if it does not complete in the specified duration, and RMAN reports an error. If the backup command is part of a RUN block, then subsequent commands in the RUN block do not execute.

Whether PARTIAL is used or not, all backup sets completed before the backup is interrupted are retained and can be used in RESTORE and RECOVER operations.


forRecoveryOfSpec

This subclause specifies that a backup should be used in an incrementally updated backup strategy. You must specify INCREMENTAL LEVEL 1 when specifying FOR RECOVER OF. Refer to forRecoveryOfSpec::= for the syntax diagram.

Syntax Element Description
FOR RECOVER OF COPY Specifies that this incremental backup should contain all changes since the SCN of a specified datafile copy (level 0 incremental backup) of the target database (see Example 2-20).

A BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY command can create backup sets or image copies. RMAN creates backup sets if an incremental level 0 image copy already exists, but otherwise creates image copies.

The datafile copies should be identified with either a DATAFILE COPY or WITH TAG clause, to separate the incremental backup strategy for which this backup will be used from the rest of your backup strategies. Otherwise, the most recent copy of each datafile will be used as the basis for the incremental backup.

See Also: Oracle Database Backup and Recovery User's Guide to learn how to make incrementally updated backups

   WITH TAG tag_name Specifies the tag of the level 0 incremental backup serving as the basis of the incremental backup.

If no level 0 backup with the tag specified in the WITH TAG parameter is found in either the current or parent database incarnation, then FOR RECOVER OF COPY option creates a level 0 datafile copy tagged with the value specified in the WITH TAG parameter.

By using the BACKUP INCREMENTAL ... FOR RECOVER OF COPY WITH TAG syntax, you can create level 1 incremental backups suitable for rolling forward a level 0 incremental image copy backup of your database. You can then use RECOVER COPY OF ... WITH TAG to perform incremental updates of a backup. This technique is used in the Enterprise Manager strategy for backups to disk.


   DATAFILECOPY
   FORMAT formatSpec
Specifies a pattern for naming the output image copies.

FOR RECOVER OF TAG
tag_name
Backs up the archived redo log files or incremental backups that are intended to recover the level 0 incremental backup specified by tag_name.

For example, the BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF TAG wholedb ARCHIVELOG ALL command backs up all archived redo log files needed to recover the level 0 incremental backup tagged wholedb.


notBackedUpSpec

This subclause specifies that RMAN should only back up files that have not yet been backed up. Refer to notBackedUpSpec::= for the syntax diagram.

Syntax Element Description
NOT BACKED UP Backs up only those files—of the files specified on the BACKUP command—that RMAN has never backed up (see Example 2-28).

This subclause is a convenient way to back up new datafiles after adding them to the database. Note that RMAN does not examine datafile checkpoints, but backs up any datafile that is not already backed up. You can also specify NOT BACKED UP when backing up backup sets.

Using BACKUP with this clause does manually what an archived redo log deletion policy can do automatically. If you specify the CONFIGURE ARCHIVELOG DELETION POLICY TO BACKED UP integer TIMES command, then a BACKUP ARCHIVELOG ALL command copies all logs unless integer backups already exist on the specified device type. If integer backups of the logs exist, then the BACKUP command skips the logs. In this way, the archived log deletion policy functions as a default NOT BACKED UP integer TIMES clause on the BACKUP command.

Note: This clause overrides backup optimization (CONFIGURE BACKUP OPTIMIZATION) and archived log deletion policies (CONFIGURE ARCHIVELOG DELETION POLICY).

   integer TIMES Backs up only those archived redo log files that have not been backed up at least integer times.

Note: You can only specify NOT BACKED UP integer TIMES when backing up archived redo log files into backup sets.

To determine the number of backups for a file, RMAN only considers backups created on the same device type as the current backup.

This option is a convenient way to back up archived logs on a specified media. For example, you want to keep at least three copies of each log on tape.


   SINCE TIME
    'date_string'
Specifies the date after which RMAN should back up files that have no backups.

The date_string is either a date in the current NLS_DATE_FORMAT or a SQL date expression such as 'SYSDATE-1'. When calculating the number of backups for a file, RMAN only considers backups created on the same device type as the current backup.

This option is a convenient way to back up datafiles that were not backed up during a previous failed backup. For example, you back up the database, but the instance fails halfway through. You can restart the backup with the NOT BACKED UP SINCE TIME clause and avoid backing up those files that you already backed up. If AS BACKUPSET is specified, then this feature is only useful if RMAN generates multiple backup sets during the backup.

When determining whether a file has been backed up, the SINCE date is compared with the completion time of the most recent backup. For BACKUP AS BACKUPSET, the completion time for a file in a backup set is the completion time of the entire backup set. In other words, all files in the same backup set have the same completion time.


sizeSpec

This subclause specifies the size of data. Refer to sizeSpec::= for the syntax diagram.

Syntax Element Description
integer [G | K | M] Specifies the size of data in gigabytes (G), kilobytes (K), or megabytes (M).

skipSpec

This subclause specifies which files to skip. Refer to skipSpec::= for the syntax diagram.

Syntax Element Description
SKIP Excludes datafiles or archived redo logs from the backup according to the criteria specified by the following keywords.

Note: You can also specify this option in the backupSpec clause.

   INACCESSIBLE Specifies that datafiles or archived redo logs that cannot be read due to I/O errors should be excluded from the backup.

A datafile is only considered inaccessible if it cannot be read. Some offline datafiles can still be read because they still exist on disk. Others have been deleted or moved and so cannot be read, making them inaccessible.

   OFFLINE Specifies that offline datafiles should be excluded from the backup.
   READONLY Specifies that read-only datafiles should be excluded from the backup.

Examples

Example 2-15 Backing Up a Database

This example starts the RMAN client from the operating system command line and then connects to a target database using operating system authentication. The BACKUP command backs up all datafiles, the current control file, the server parameter file, and archived redo log files to the default storage device:

% rman
RMAN> CONNECT TARGET /
RMAN> BACKUP DATABASE PLUS ARCHIVELOG;

Example 2-16 Performing a Cumulative Incremental Backup

This example backs up all blocks changed in the database since the most recent level 0 incremental backup. If no level 0 backup exists when you run a level 1 backup, then RMAN makes a level 0 backup automatically. Any inaccessible files are skipped.

BACKUP 
  INCREMENTAL LEVEL 1 CUMULATIVE
  SKIP INACCESSIBLE 
  DATABASE;

Example 2-17 Distributing a Backup Across Multiple Disks

This example backs up tablespaces to two different disks and lets RMAN perform automatic parallelization of the backup. The %U in the FORMAT string is a substitution variable that generates a unique filename for each output image copy.

RUN
{
  ALLOCATE CHANNEL dev1 DEVICE TYPE DISK FORMAT '/disk1/%U';
  ALLOCATE CHANNEL dev2 DEVICE TYPE DISK FORMAT '/disk2/%U'; 
  BACKUP AS COPY
    TABLESPACE SYSTEM, tools, users, undotbs;
}

Example 2-18 Identifying Datafile Copies by Tag

In this example, you back up datafile image copies to tape. The BACKUP command locates all datafile copies with the tag LATESTCOPY, backs them up to tape, and names the backups by means of substitution variables. The variable %f specifies the absolute file number, whereas %d specifies the name of the database. After the datafile copies are on tape, the example deletes all image copies with the tag LATESTCOPY.

BACKUP 
  DEVICE TYPE sbt
  DATAFILECOPY 
    FROM TAG 'LATESTCOPY'
  FORMAT 'Datafile%f_Database%d';
DELETE COPY TAG 'LATESTCOPY';

Example 2-19 Backing Up and Deleting Archived Redo Logs

This example assumes that you have two archiving destinations set: /disk2/PROD/archivelog/ and /disk1/arch/. The command backs up one archived redo log for each unique sequence number. For example, if archived redo log 1000 is in both directories, then RMAN only backs up one copy this log. The DELETE INPUT clause with the ALL keyword specifies that RMAN should delete all archived redo log files from both archiving directories after the backup.

BACKUP DEVICE TYPE sbt
  ARCHIVELOG LIKE '/disk%arc%'
  DELETE ALL INPUT;

Sample output for the preceding command appears as follows:

Starting backup at 12-MAR-07
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: SID=150 device type=SBT_TAPE
channel ORA_SBT_TAPE_1: Oracle Secure Backup
channel ORA_SBT_TAPE_1: starting archived log backup set
channel ORA_SBT_TAPE_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=4 RECID=4 STAMP=616789551
input archived log thread=1 sequence=5 RECID=5 STAMP=616789551
input archived log thread=1 sequence=6 RECID=6 STAMP=616789554
input archived log thread=1 sequence=7 RECID=7 STAMP=616789731
input archived log thread=1 sequence=8 RECID=8 STAMP=616789825
input archived log thread=1 sequence=9 RECID=10 STAMP=616789901
input archived log thread=1 sequence=10 RECID=12 STAMP=616789985
channel ORA_SBT_TAPE_1: starting piece 1 at 12-MAR-07
channel ORA_SBT_TAPE_1: finished piece 1 at 12-MAR-07
piece handle=0vice0g7_1_1 tag=TAG20070312T105917 comment=API Version 2.0,MMS Version 10.1.0.3
channel ORA_SBT_TAPE_1: backup set complete, elapsed time: 00:00:25
channel ORA_SBT_TAPE_1: deleting archived log(s)
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_4_2z45sgrc_.arc RECID=4 STAMP=616789551
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_5_2z45sgrc_.arc RECID=5 STAMP=616789551
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_6_2z45sl3g_.arc RECID=6 STAMP=616789554
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_7_2z45z2kt_.arc RECID=7 STAMP=616789731
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_8_2z4620sk_.arc RECID=8 STAMP=616789825
archived log file name=/disk1/arch/archiver_1_8_616789153.arc RECID=9 STAMP=616789825
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_9_2z464dhk_.arc RECID=10 STAMP=616789901
archived log file name=/disk1/arch/archiver_1_9_616789153.arc RECID=11 STAMP=616789901
archived log file name=/disk2/PROD/archivelog/2007_03_09/o1_mf_1_10_2z4670gr_.arc RECID=12 STAMP=616789985
archived log file name=/disk1/arch/archiver_1_10_616789153.arc RECID=13 STAMP=616789985
Finished backup at 12-MAR-07
 
Starting Control File and SPFILE Autobackup at 12-MAR-07
piece handle=c-28643857-20070312-02 comment=API Version 2.0,MMS Version 10.1.0.3
Finished Control File and SPFILE Autobackup at 12-MAR-07

Example 2-20 Scripting Incrementally Updated Backups

By incrementally updating backups, you can avoid the overhead of making full image copy backups of datafiles, while also minimizing time required for media recovery of your database. For example, if you run a daily backup script, then you never have more than one day of redo to apply for media recovery.

Assume you run the following script daily. On first execution, the script creates an image copy backup of the database on disk with the specified tag. On second execution, the script creates a level 1 backup of the database. On every subsequent execution, RMAN applies the level 1 incremental to the datafile copy and then makes a new level 1 backup.

RUN
{
  RECOVER COPY OF DATABASE 
    WITH TAG 'incr_update';
  BACKUP
    INCREMENTAL LEVEL 1
    FOR RECOVER OF COPY WITH TAG 'incr_update'
    DATABASE;
}

Example 2-21 Backing Up Disk-Based Backup Sets to Tape

Assume your goal is to keep recent backup sets on disk and older backup sets on tape. Also, you want to avoid keeping copies of the same backup set on disk and tape simultaneously. This example backs up backup sets created more than two weeks ago to tape and then deletes the backup pieces from disk.

BACKUP
  DEVICE TYPE sbt 
  BACKUPSET
    COMPLETED BEFORE 'SYSDATE-14' 
  DELETE INPUT;

Example 2-22 Duplexing a Database Backup

This example uses the COPIES parameter to create two compressed backups of the database, with each backup on a separate disk. The output locations are specified in the FORMAT parameter.

BACKUP AS COMPRESSED BACKUPSET
  DEVICE TYPE DISK 
  COPIES 2
  DATABASE
  FORMAT '/disk1/db_%U', '/disk2/db_%U';

Example 2-23 Specifying How Channels Divide Workload

This example explicitly parallelizes a backup by using the CHANNEL parameter to specify which channels should back up which files and to which locations.

RUN
{
  ALLOCATE CHANNEL ch1 DEVICE TYPE sbt
    PARMS 'ENV=(OB_DEVICE_1=stape1)';
  ALLOCATE CHANNEL ch2 DEVICE TYPE sbt
    PARMS 'ENV=(OB_DEVICE_1=stape2)';
  BACKUP 
    (DATABASE        # ch1 backs up database to tape drive stape1
      CHANNEL ch1)
    (ARCHIVELOG ALL
      CHANNEL ch2);  # ch2 backs up archived redo logs to tape drive stape2
}

Example 2-24 Creating an Incremental Backup for Refresh of a Standby Database

In this example, your goal is make an incremental backup of the primary database and use it to update an associated standby database. You start the RMAN client, CONNECT to the primary database as TARGET, and then connect to the recovery catalog. The BACKUP command creates an incremental backup of the primary database that can be applied at a standby database to update it with changes since the specified SCN.

RMAN> CONNECT TARGET /

connected to target database: PROD (DBID=39525561)

RMAN> CONNECT CATALOG rman@catdb

recovery catalog database Password: password
connected to recovery catalog database

RMAN> BACKUP DEVICE TYPE DISK
2> INCREMENTAL FROM SCN 404128 DATABASE
3>  FORMAT '/disk1/incr_standby_%U';

Example 2-25 Specifying Corruption Tolerance for Datafile Backups

This example assumes a database that contains 5 datafiles. It uses the SET MAXCORRUPT command to indicate than no more than 1 corruption should be tolerated in each datafile. Because the CHECK LOGICAL option is specified on the BACKUP command, RMAN checks for both physical and logical corruption.

RUN
{
  SET MAXCORRUPT FOR DATAFILE 1,2,3,4,5 TO 1;
  BACKUP CHECK LOGICAL
    DATABASE;
}

Example 2-26 Creating a Consistent Database Backup for Archival Purposes

This example uses a keepOption to create an archival backup set that cannot be considered obsolete for one year. The example backs up the database, archives the redo in the current online logs to ensure that this new backup is consistent, and backs up only those archived logs needed to restore the datafile backup to a consistent state.

The BACKUP command also creates a restore point to match the SCN at which this backup will be consistent. Note that the FORMAT parameter must be capable of creating multiple backup pieces in multiple backup sets.

BACKUP DATABASE
  FORMAT '/disk1/archival_backups/db_%U.bck' 
  TAG quarterly
  KEEP UNTIL TIME 'SYSDATE + 365'
  RESTORE POINT Q1FY06;

Example 2-27 Exempting Copies from the Retention Policy

The following example copies two datafiles and exempts them from the retention policy forever. (Note that KEEP FOREVER requires a recovery catalog.) The control file and server parameter file will also be backed up, even with autobackup off.

SHUTDOWN IMMEDIATE;
STARTUP MOUNT;
BACKUP
  KEEP FOREVER
  FORMAT '?/dbs/%U_longterm.cpy'
  TAG LONGTERM_BCK
  DATAFILE 1 DATAFILE 2;
ALTER DATABASE OPEN;

Example 2-28 Backing Up Files That Need Backups

Assume that you back up the database and archived logs every night to tape by running the following command.

BACKUP
  MAXSETSIZE 500M
  DATABASE PLUS ARCHIVELOG;

The preceding command sets an upper limit to the size of each backup set so that RMAN produces multiple backup sets. Assume that the media management device fails halfway through the backup and is then restarted. The next day you discover that only half the backup sets completed. In this case, you can run the following command in the evening:

BACKUP 
  NOT BACKED UP SINCE TIME 'SYSDATE-1'
  MAXSETSIZE 500M
  DATABASE PLUS ARCHIVELOG;

With the preceding command, RMAN backs up only files not backed up during in the previous 24 hours. When RMAN determines that a backup from the specified time window is available, it displays output like the following:

skipping datafile 1; already backed up on 18-JAN-07
skipping datafile 2; already backed up on 18-JAN-07
skipping datafile 3; already backed up on 18-JAN-07

If you place the NOT BACKED UP SINCE clause immediately after the BACKUP command, then it affects all objects to be backed up. You can also place it after individual backupSpec clauses to cause only backups for those objects described by the backupSpec to be subject to the limitation.

Example 2-29 Using NODUPLICATES To Back Up Datafile Copies

This example creates a datafile copy of datafile 2 named /disk2/df2.cpy. The example then backs up this datafile copy to the /disk1 and /disk3 directories. The NODUPLICATES option on the final BACKUP command indicates that only one copy of datafile 2 should be backed up.

BACKUP AS COPY
  DATAFILE 2
  FORMAT '/disk2/df2.cpy' TAG my_tag;
BACKUP AS COPY
  DATAFILECOPY '/disk2/df2.cpy' 
  FORMAT '/disk1/df2.cpy';
BACKUP AS COPY
  DATAFILECOPY '/disk1/df2.cpy' 
  FORMAT '/disk3/df2.cpy';
BACKUP
  DEVICE TYPE sbt
  DATAFILECOPY ALL NODUPLICATES; # backs up only copy of datafile 2