RESTORE

Syntax

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restoreObject::=

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restoreSpecOperand::=

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Purpose

To restore files from backups or image copies. By default, RMAN restores files to their default location. You can use the SET NEWNAME command to restore files to nondefault locations. RMAN restores backups from disk or tape and restores images copies from disk only.

Typically, you restore when a media failure has damaged a current datafile, control file, or archived log or prior to performing a point-in-time recovery. The RESTORE command restores full backups, incremental backups (level 0 only), or copies of datafiles, control files, and archived redo logs. Because the RECOVER command automatically restores archived logs as needed, you should seldom need to restore logs manually. Possible reasons for manually restoring archived logs are to speed up recovery or to stage the logs to multiple destinations.

Note: In Oracle9i, unlike in previous RMAN releases, RMAN by default does not restore a datafile if the file is in the correct place and its header contains the expected data (RMAN does not scan the datafile body for corrupt blocks). The FORCE option overrides this behavior and restores the requested files unconditionally.

When you perform a restore operation by using a backup control file and use a recovery catalog, RMAN automatically adjusts the control file to reflect the structure of the restored database.

If you restore to the default location, then RMAN overwrites files with the same filenames. If you restore to a new location, then issue SET NEWNAME commands to rename the files and issue a SWITCH command to make the restored files current. If you do not issue SWITCH commands, then RMAN considers the restored files as valid copies for use in future restore operations.

If you do not manually allocate channels, then RMAN allocates all automatic channels possibly needed by the RESTORE command. For example, assume you configure 3 separate sbt channels (each with different PARMS) and then configure parallelism for DISK and sbt as follows:

CONFIGURE DEVICE TYPE DISK PARALLELISM 2;
CONFIGURE DEVICE TYPE sbt PARALLELISM 3;
CONFIGURE DEFAULT DEVICE TYPE TO sbt;

During a restore, RMAN allocates three sbt channels and the two preconfigured DISK channels. For a restore, RMAN allocates all configured channels unless the DEVICE TYPE option restricts the device type from which RMAN restores files.

See Also: Oracle9i Recovery Manager User's Guide to learn how to restore files

Restrictions and Usage Notes

• To restore datafiles to their current location, the database must be started, mounted, or open with the tablespaces or datafiles to be restored offline. If the database is only started, then it is recommended that you only restore the control file, if necessary. To restore other files, mount the database and then continue.

  Note: When performing a database validation by using RESTORE ... VALIDATE, the database can be open.

• To restore to a new location, use the SET NEWNAME commands to rename the datafiles and use SWITCH commands to make them the current database files. If you do not use SWITCH, then the repository lists the restored datafile as a datafile copy.

• If you use the FROM DATAFILECOPY option, then the allocated channels must be of DEVICE TYPE DISK.

• If you use the FROM BACKUPSET operand, then the appropriate type of storage devices must be allocated for the backup sets that need to be restored. If the appropriate device is not allocated, then you may not be able to find a candidate backup set or copy to restore, and the RESTORE command fails.

• RMAN only restores backups that were created on the same type of channels that are allocated for the RESTORE command.

  For example, if you made some backups of a datafile to DISK channels and others to sbt channels, and only a DISK channel is allocated for the RESTORE command, RMAN will not restore backups that were created on sbt channels.

• If datafile filenames are symbolic links, that is, files pointing to other files, then the control file contains the filenames of the link files but RMAN performs I/O on the datafiles pointed to by the link files. If a link file is lost and you RESTORE a datafile without first re-creating the symbolic link, then RMAN restores the datafile to the location of the link file rather than to the location pointed to by the link.

• Open the database RESETLOGS after restoring with a backup control file.

• You can only restore from a previous incarnation when restoring the whole database. For example, you cannot restore one datafile of a previous incarnation while the current database is in a different incarnation.

• Do not specify a datafile more than once in a restore job. For example, the following command is illegal because datafile 1 is both specified explicitly and implied by the SYSTEM tablespace:

  RESTORE TABLESPACE SYSTEM DATAFILE 1;
  
  

• If you restore a control file from a release earlier than release 8.1.6 on Windows NT that has not been normalized, then you must normalize it before mounting the database by following the procedure described in Oracle9i Database Migration. A flawed mechanism in releases prior to release 8.1.6 on Windows NT could allow two different filenames to refer to the same physical file.

• If you restore the control file and do not specify TO 'filename', then the database must be started but not mounted. RMAN restores the control file to the first location specified in the parameter file and then replicates it to all other locations. When the database is not mounted, you must set the DBID using the SET command or the restore fails. If you specify the TO 'filename' option, then RMAN only restores the control file to the specified location. In this case, you do not need to set the DBID because RMAN takes the value from the control file.

• You must have already configured a device type by using CONFIGURE (except for DISK, which is preconfigured) before specifying the DEVICE TYPE option.

• You cannot manually allocate channels and then run RECOVER with the DEVICE TYPE option.

• RMAN neither backs up nor restores temporary tablespaces.

Keywords and Parameters

restoreObject	Specifies the objects to be restored.
	CONTROLFILE	Restores the current control file to the default location and automatically replicates it to all CONTROL_FILES locations in the initialization parameter file. The default location is the first filename specified in the CONTROL_FILES parameter. If you specify a new path name with the TO 'filename' option, then RMAN restores the control file to the new location: you must replicate it manually with the REPLICATE command. Note that you must always run the RECOVER command after restoring a control file, and must also always open the database with the RESETLOGS option.
	DATABASE	Restores all datafiles in the database except those that are offline or read-only. Unlike BACKUP DATABASE, RESTORE DATABASE does not automatically include the control file--you must issue an additional RESTORE command to perform this operation. If you specify the CHECK READONLY option, then RMAN examines the headers of all read-only files and restores any that need restoring. Use an optional SKIP TABLESPACE 'tablespace_name' argument to avoid restoring specified tablespaces, which is useful when you want to avoid restoring tablespaces containing temporary data. If you specify SKIP FOREVER TABLESPACE, then RMAN specifies the DROP option of ALTER DATABASE DATAFILE ... OFFLINE when taking the datafiles that belong to the tablespace offline before the restore. The DROP option indicates that RMAN does not intend to recover these files and intends to drop their tablespaces from the database after the database is opened again. In other words, FOREVER indicates that RMAN never intends to do anything with the skipped tablespaces again.
	DATAFILE datafileSpec	Restores the datafiles specified by filename or absolute datafile number. See Also: "datafileSpec"
	TABLESPACE 'tablespace_name'	Restores all datafiles in the specified tablespaces.
	archivelogRecordSpecifier	Restores the specified range of archived redo logs. See Also: "archivelogRecordSpecifier" Note: The database can be started, mounted, or open for this operation.
restoreSpecOperand	specifies options for the restoreObject clause. Note: These parameters override the parameters with the same name at the RESTORE command level.
	CHANNEL 'channel_id'	Specifies the case-sensitive name of a channel to use for this restore operation. If you do not specify a channel, then RESTORE uses any available channel allocated with the correct device type.
	FROM TAG = 'tag_name'	Overrides the default selection of the most recent backups or file copy available. The tag restricts the automatic selection to backup sets or file copies that were created with the specified tag. If multiple backup sets or file copies have a matching tag, then RMAN selects the most recent one.
	PARMS 'channel_parms'	Specifies a quoted string containing operating system-specific information. The string is passed to the operating system dependent layer each time a backup piece is restored.
	FROM AUTOBACKUP	Restores a control file autobackup. You can only specify this option on the RESTORE CONTROLFILE command. RMAN begins the search on the current day or on the day specified with the SET UNTIL. If no autobackup is found in the current or SET UNTIL day, RMAN checks the previous day starting with sequence 256 (or the sequence specified by MAXSEQ) until it reaches 0. The search continues up to MAXDAYS days (default of 7, maximum of 366) from the current or SET UNTIL day. If no autobackup is found within MAXDAYS days, then RMAN signals an error and the command stops. Note these restrictions when restoring an autobackup: You must run SET DBID when the target database is in NOMOUNT mode and you are not using a recovery catalog. If you do not specify TO 'filename', then the database must be started but not mounted. RMAN restores the control file to the first location specified in the parameter file and then replicates to all other locations. If you specify TO 'filename', then RMAN only restores the control file to the specified location. In this case, you do not need to run SET DBID because RMAN takes the value from the control file.
	FROM 'media_handle'	Specifies the name of the backup piece containing a control file backup. The media_handle can be any backup piece that contains a backup of a control file: the control file backup does not need to be an autobackup. Refer to the FROM AUTOBACKUP description for restrictions involving the restore of a control file autobackup.
CHANNEL 'channel_id'	Refer to the restoreSpecOperand clause.
PARMS 'channel_parms'	Refer to the restoreSpecOperand clause.
FROM {BACKUPSET | DATAFILECOPY}	Specifies whether RMAN should restore from a DATAFILECOPY on disk or a BACKUPSET. By default RESTORE chooses the most recent backup set or file copy, that is, the file copy or backup set that needs the least media recovery.
untilClause	Limits the selection to those backup sets or file copies that would be suitable for performing an incomplete recovery to the specified time. In the absence of any other criteria, RMAN selects the most current file copy or backup set to restore. See Also: "untilClause"
FROM TAG = 'tag_name'	Refer to the restoreSpecOperand clause.
VALIDATE	Causes RMAN to decide which backup sets, datafile copies, and archived logs need to be restored and then scans them to verify their contents. This operation creates no output files. Specify this option periodically to verify that the copies and backup sets required to restore the specified files are intact and usable.
CHECK LOGICAL	Tests data and index blocks that pass physical corruption checks for logical corruption, for example, corruption of a row piece or index entry. If RMAN finds logical corruption, it logs the block in the alert.log and server session trace file. If the sum of physical and logical corruptions for a file remain below its MAXCORRUPT setting, the RMAN command completes and Oracle populates the V$BACKUP_CORRUPTION and V$COPY_CORRUPTION views with corrupt block ranges. If MAXCORRUPT is exceeded, the command terminates without populating the views. Note: The MAXCORRUPT setting represents the total number of physical and logical corruptions permitted on a file.
CHECK READONLY	Checks the read-only datafiles to make sure they exist, are readable, and have the appropriate checkpoint. If any of these conditions is not met, then RMAN restores the files--whether or not they are read-only. By default, RMAN does not restore read-only files when you issue the RESTORE DATABASE command.
DEVICE TYPE deviceSpecifier	Allocates automatic channels for the specified device type only. For example, if you configure automatic disk and tape channels, and issue RESTORE ... DEVICE TYPE DISK, then RMAN allocates only disk channels. See Also: "deviceSpecifier"
FORCE	Overrides the restartable restore feature and restores all files regardless of whether they need to be restored. If you do not specify FORCE, then RMAN restores a file only if its header information does not match the information in the control file.

Examples

Restoring a Tablespace: Example

This example takes a tablespace offline, restores it, then performs media recovery:

SQL "ALTER TABLESPACE TBS_1 OFFLINE IMMEDIATE"; 
RESTORE TABLESPACE tbs_1; 
RECOVER TABLESPACE tbs_1;  
SQL "ALTER TABLESPACE TBS_1 ONLINE";

Restoring the Control File: Example

This example restores the control file to its default location, replicates it to all multiplexed locations, and mounts the database:

RUN
{
  STARTUP FORCE NOMOUNT;
  RESTORE CONTROLFILE; 
  ALTER DATABASE MOUNT;
}

Restoring the Control File Using a Tag: Example

This example restores the control file specified by a tag, replicates it, and then mounts the database:

STARTUP NOMOUNT;
RESTORE CONTROLFILE FROM TAG 'monday_cf_backup'; 
ALTER DATABASE MOUNT;

Restoring the Database Using a Backup Control File: Example

This example restores the control file, replicates it to all control file locations specified in the parameter file, and then mounts the control file in order to restore the database:

STARTUP NOMOUNT;
RUN
{
  ALLOCATE CHANNEL c1 DEVICE TYPE sbt;
  RESTORE CONTROLFILE;
  ALTER DATABASE MOUNT;
  RESTORE DATABASE;
}

Restoring Archived Redo Logs to a New Location: Example

This example restores all archived redo logs to the /oracle/temp_restore directory:

RUN
{ 
  SET ARCHIVELOG DESTINATION TO '/oracle/temp_restore';
  RESTORE ARCHIVELOG ALL;
}

Restoring a Control File Autobackup to a Nondefault Location: Example

This example restores the latest control file autobackup made on or before June 23, 2000 with a nondefault format of PROD_CF_AUTOBACKUP_%F. It starts searching for backups with a sequence number of 20, and searches backwards for 5 months:

RUN
{
  SET UNTIL TIME '23-JUN-2000 00:00:00';
  SET CONTROLFILE AUTOBACKUP FORMAT TO 'PROD_CF_AUTOBACKUP_%F';
  ALLOCATE CHANNEL CHANNEL_1 DEVICE TYPE sbt;
  RESTORE CONTROLFILE TO '/tmp/autobackup_20001002.dbf' FROM AUTOBACKUP 
    MAXSEQ 20 MAXDAYS 150;
}