The preceding chapters in Diagnosing and Responding to Failures cover the most basic recovery scenarios and are intended to be as generic as possible. The scenarios in this chapter are less common or are more complicated than the basic scenarios.
You can perform limited recovery of changes to a database running in NOARCHIVELOG mode by applying incremental backups. The incremental backups must be consistent, like all backups of a database run in NOARCHIVELOG mode, so you cannot make backups of the database when it is open.
Rman Backup And Recovery Scenarios In Oracle 11g Pdf Download
If you changed the archiving destination or format during recovery, or if you added new online log members after the backup of the control file, then RMAN may not be able to automatically catalog a needed online or archived log. Whenever RMAN cannot find online redo logs and you did not specify an UNTIL time, RMAN reports errors similar to the following:
The discussion of RESTORE CONTROLFILE in Oracle Database Backup and Recovery Reference for more details about restrictions on using RESTORE CONTROLFILE in different scenarios (such as when using a recovery catalog, or restoring from a specific backup)
When RMAN is connected to a recovery catalog, the recovery procedure with a backup control file is identical to recovery with a current control file. The RMAN metadata missing from the backup control file is available from the recovery catalog. The only exception is if the database name is not unique in the catalog, in which case you must use SET DBID command before restoring the control file.
If you are not using a recovery catalog, then you must restore your control file from an autobackup. To restore the control file from autobackup, the database must be in a NOMOUNT state. You must first set the DBID for your database, and then use the RESTORE CONTROLFILE FROM AUTOBACKUP command.
If the database uses a fast recovery area, then RMAN updates a control file restored from backup by crosschecking all disk-based backups and image copies recorded in the control file. RMAN catalogs any backups in the recovery area that are not recorded. As a result, the restored control file has a complete and accurate record of all backups in the recovery area and any other backups known to the control file at the time of the backup.
This section assumes that you have RMAN backups of the control file, but do not use a recovery catalog. It also assumes that you enabled the control file autobackup feature for the target database and can restore an autobackup of the control file.
Because you are not connected to a recovery catalog, the RMAN repository contains only information about available backups at the time of the control file backup. If you know the location of other usable backup sets or image copies, then add them to the control file RMAN repository with the CATALOG command.
The procedure for disaster recovery is similar to the procedure for recovering the database with a backup control file in NOCATALOG mode. If you are restoring the database to a new host, then review the considerations described in "Restoring a Database on a New Host".
Use the RESTORE and RECOVER commands to restore a database on a new host. Restoring a database on a new host is useful when you want to perform a test run of your disaster recovery procedures or to permanently move a database to a new host.
If you must use a recovery catalog because the control file is not large enough to contain the RMAN repository data on all of the backups that you must restore, then use Oracle Data Pump to export the catalog and import it into a different schema or database. Afterward, use the copied recovery catalog for the test restore. Otherwise, the recovery catalog considers the restored database as the current target database.
To move the database to a new host by using data file copies or backup sets on disk, you must transfer the files manually to the new host. This procedure assumes that RMAN is using a recovery catalog.
Now, assume that the directory structure of hostb is different from hosta. The target database is located in /net/hosta/dev3/oracle/dbs, but you want to restore the database to /net/hostb/oracle/oradata/test. You have tape backups of data files, control files, archived redo logs, and the server parameter file on a media manager accessible by both hosts. The ORACLE_SID for the TRGTA database is TRGTA and does not change for the restored database.
To test disaster recovery, you must have a recoverable backup of the target database. When preparing your disaster recovery strategy, ensure that the backups of the data files, control files, and server parameter file are restorable on hostb. Thus, you must configure the media management software so that hostb is a media manager client and can read the backup sets created on hosta. Consult the media management vendor for support on this issue.
In this example, the source database is an Oracle Database 11g Release 2 database and it is configured to use a server parameter file (spfile). The database runs in ARCHIVELOG mode and uses a fast recovery area. Control file autobackups are also configured. You then create RMAN backups of the source database, including the archived redo logs.
RMAN is connected as TARGET to the physical standby database. The recovery process is optimized by restoring only the used data blocks in a data file. Use the FROM SERVICE clause to specify the service name of the primary database from which the incremental backup must be fetched.
To use multisection backup sets during the recovery process, specify the SECTION SIZE clause in the RECOVER command. To transfer the required files from the primary database as encrypted backup sets, use the SET ENCRYPTION command before the RESTORE command to specify the encryption algorithm used to create the backup sets.
The preceding chapters in Part V, "Diagnosing and Responding to Failures" cover the most basic recovery scenarios and are intended to be as generic as possible. The scenarios in this chapter are advanced in the sense that they are not as common or are more complicated than the basic scenarios.
If all copies of the current control file are lost or damaged, then you must restore and mount a backup control file. You must then run the RECOVER command, even if no datafiles have been restored, and open the database with the RESETLOGS option. If some copies of the current control file are usable, however, then you can follow the procedure in "Responding to the Loss of a Subset of the Current Control Files" and avoid the recovery and RESETLOGS.
If you are not using a recovery catalog, then you must restore your control file from an autobackup. To restore the control file from autobackup, the database must be in a NOMOUNT state. As shown in Example 19-2, you must first set the DBID for your database, and then use the RESTORE CONTROLFILE FROM AUTOBACKUP command.
The commands for restoring a control file are the same whether or not the database uses a fast recovery area. If the database uses a recovery area, then RMAN updates a control file restored from backup by crosschecking all disk-based backups and image copies recorded in the control file. RMAN catalogs any backups in the recovery area that are not recorded. As a result, the restored control file has a complete and accurate record of all backups in the recovery area and any other backups known to the control file at the time of the backup.
The procedure for disaster recovery is similar to the procedure for recovering the database with a backup control file in NOCATALOG mode. If you are restoring the database to a new host, then you should also review the considerations described in "Restoring a Database on a New Host".
If your goal is to perform a test run of your disaster recovery procedures, or to permanently move a database to a new host, then you can use the procedure in this section. This procedure uses the RESTORE and RECOVER commands.
If you must use a recovery catalog because the control file is not large enough to contain the RMAN repository data on all of the backups that you need to restore, then use Oracle Data Pump to export the catalog and import it into a different schema or database. Afterward, use the copied recovery catalog for the test restore. Otherwise, the recovery catalog considers the restored database as the current target database.
To move the database to a new host by means of datafile copies or backup sets on disk, you must transfer the files manually to the new host. This example assumes that RMAN is using a recovery catalog. 2ff7e9595c
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