16 Performing Complete Database Recovery
Use RMAN to return your database to normal operation after the loss of one or more data files.
16.1 Overview of Complete Database Recovery
Complete recovery returns your database to normal operation after the loss of one or more database files.
This section contains the following topics:
16.1.1 Purpose of Complete Database Recovery
Complete recovery is recovering a database to the most recent point in time, without the loss of any committed transactions.
This chapter assumes that some or all of your data files are lost or damaged. Typically, this situation is caused by a media failure or accidental deletion. Your goal is to return the database to normal operation by restoring the damaged files from RMAN backups and recovering all database changes.
16.1.2 Scope of This Chapter
The complete recovery operations described in this chapter are subject to certain conditions.
This chapter makes the following assumptions:
-
You have lost some or all data files and your goal is to recover all changes, but you have not lost all current control files or an entire online redo log group.
-
Your database is using the current server parameter file.
-
You have the complete set of archived redo logs and incremental backups needed for recovery of your data file backups. Every data file either has a backup, or a complete set of online and archived redo logs goes back to the creation of a data file with no backup.
RMAN can handle lost data files without user intervention during restore and recovery. When a data file is lost, the possible cases can be classified as follows:
-
The control file knows about the data file, that is, you backed up the control file after data file creation, but the data file itself is not backed up. If the data file record is in the control file, then
RESTORE
creates the data file in the original location or in a user-specified location. TheRECOVER
command can then apply the necessary logs to the data file. -
The control file does not have the data file record, that is, you did not back up the control file after data file creation. During recovery, the database detects the missing data file and reports it to RMAN, which creates a data file and continues recovery by applying the remaining logs. If the data file was created in a parent incarnation, then it is created during the restore or recovery phase as appropriate.
-
-
You are not restoring and recovering an encrypted tablespace.
If you perform media recovery on an encrypted tablespace, then the Oracle keystore must be open when performing media recovery of this tablespace.
-
Your database runs in a single-instance configuration.
Although RMAN can restore and recover databases in Oracle RAC and Data Guard configurations, these scenarios are beyond the scope of this manual.
-
You are using the RMAN client rather than Oracle Enterprise Manager.
See Also:
-
"Performing Flashback and Database Point-in-Time Recovery" for information about recovering some but not all database changes
-
"Performing Recovery with a Backup Control File" for information about recovering the database when all control files are lost
-
"Restoring the Server Parameter File" for information about restoring a backup server parameter file
16.1.3 About Real-time Redo Transport for Recovery Appliance
Zero Data Loss Recovery Appliance (Recovery Appliance) substantially reduces the window of potential data loss that exists between successive archived redo log backups. You to recover target databases to within a few subseconds of a database failure.
When real-time redo transport is configured for a target database, redo data from the current redo log groups is written asynchronously to Recovery Appliance as it is generated. As the redo stream is received, it is stored as a complete RMAN archived redo log. If the target database crashes, the redo data received from the current redo log group, until the time of the crash, is used during restore and recovery operations.
You must perform certain configuration steps to enable real-time redo transport for the target database.
Note:
Real-time redo transport can be used only with Recovery Appliance.
See Also:
Zero Data Loss Recovery Appliance Protected Databases Configuration Guide for the steps to configure real-time redo transport
16.2 Preparing for Complete Database Recovery
You must plan your database restore and recovery strategy based on your recovery goal and which database files have been lost.
This section contains the following topics:
16.2.1 Identifying the Database Files to Restore or Recover
The techniques for determining which files require restore or recovery depend upon the type of file that is lost.
This section contains the following topics:
16.2.1.1 Identifying a Lost Control File
The database shuts down immediately when any of the multiplexed control files become inaccessible.
If you try to start the database without a valid control file at each location specified in the CONTROL_FILES
initialization parameter, then the database reports an error.
Loss of some but not all copies of your control file does not require you to restore a control file from backup. If at least one control file remains intact, then you can either copy an intact copy of the control file over the damaged or missing control file, or update the initialization parameter file so that it does not refer to the damaged or missing control file. After the CONTROL_FILES
parameter references only present, intact copies of the control file, you can restart your database.
If you restore the control file from backup, then you must perform media recovery of the whole database and then open it with the OPEN RESETLOGS
option, even if no data files must be restored. This technique is described in "Performing Recovery with a Backup Control File".
16.2.1.2 Identifying Data Files Requiring Media Recovery
The decision about when and how to recover depends on the state of the database and the location of its data files.
Use RMAN or SQL*Plus to identify data files that require media recovery.
16.2.1.2.1 Identifying Data Files with RMAN
An easy technique for determining which data files are missing is to run a VALIDATE DATABASE
command.
Example 16-1 VALIDATE DATABASE
This example validates the database and tries to read all specified data files (sample output included).
RMAN> VALIDATE DATABASE; Starting validate at 20-OCT-13 allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=90 device type=DISK could not read file header for datafile 7 error reason 4 RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: failure of backup command at 10/20/2013 13:05:43 RMAN-06056: could not access datafile 7
VALIDATE DATABASE
command indicates that data file 7 is inaccessible. You can then run the REPORT SCHEMA
command to obtain the tablespace name and file name for data file 7 as follows (sample output included):RMAN> REPORT SCHEMA; Report of database schema for database with db_unique_name RDBMS List of Permanent Datafiles =========================== File Size(MB) Tablespace RB segs Datafile Name ---- -------- -------------------- ------- ------------------------ 1 450 SYSTEM *** +DATAFILE/tbs_01.f 2 86 SYSAUX *** +DATAFILE/tbs_ax1.f 3 15 UD1 *** +DATAFILE/tbs_undo1.f 4 2 SYSTEM *** +DATAFILE/tbs_02.f 5 2 TBS_1 *** +DATAFILE/tbs_11.f 6 2 TBS_1 *** +DATAFILE/tbs_12.f 7 2 TBS_2 *** +DATAFILE/tbs_21.f List of Temporary Files ======================= File Size(MB) Tablespace Maxsize(MB) Tempfile Name ---- -------- -------------------- ----------- -------------------- 1 40 TEMP 32767 +DATAFILE/tbs_tmp1.f
16.2.1.2.2 Identifying Data Files with SQL
Although VALIDATE DATABASE
is a good technique for determining whether files are inaccessible, you may want to use SQL queries to obtain more detailed information.
To determine whether data files require media recovery:
See Also:
-
V$DATAFILE_HEADER
in Oracle Database Reference -
V$RECOVER_FILE
in Oracle Database Reference -
V$DATAFILE
in Oracle Database Reference -
V$TABLESPACE
in Oracle Database Reference
16.2.2 Determining the DBID of the Database
It is recommended that you record the DBID of your database.
In situations requiring the recovery of your server parameter file or control file from autobackup, you must know the DBID. Be sure to record the DBID along with other basic information about your database.
If you do not have a record of the DBID of your database, then you can find it in the following places without opening your database:
-
The DBID is used in forming the file name for the control file autobackup. Locate this file, and then refer to "Configuring the Control File Autobackup Format" to determine where the DBID appears in the file name.
-
If you have any text files that preserve the output from an RMAN session, then the DBID is displayed by the RMAN client when it starts up and connects to your database. Typical output follows:
% rman TARGET / Recovery Manager: Release 12.1.0.1.0 - Production on Wed Jan 16 17:51:30 2013 Copyright (c) 1982, 2013, Oracle and/or its affiliates. All rights reserved. connected to target database: PROD (DBID=36508508)
16.2.3 Previewing Backups Used in Restore Operations
Previewing backups helps you to ensure that all backups required for a restore and recovery operation are available.
You can apply RESTORE
...
PREVIEW
to any RESTORE
operation to create a detailed list of every backup to be used in the requested RESTORE
operation, and the necessary target SCN for recovery after the RESTORE
operation is complete. This command accesses the RMAN repository to query the backup metadata, but does not actually read the backup files to ensure that they can be restored.
As an alternative to RESTORE ... PREVIEW
, you can use the RESTORE ... VALIDATE HEADER
command. In addition to listing the files needed for restore and recovery, the RESTORE ... VALIDATE HEADER
command validates the backup file headers to determine whether the files on disk or in the media management catalog correspond to the metadata in the RMAN repository.
When planning your restore and recovery operation, use RESTORE ...
PREVIEW
or RESTORE ... VALIDATE HEADER
to ensure that all required backups are available or to identify situations in which you may want to direct RMAN to use or avoid specific backups.
To preview backups to be used in a restore operation:
See Also:
Oracle Database Backup and
Recovery Referencefor details on interpreting RESTORE
...
PREVIEW
output, which is in the same format as the output of the LIST
command
16.2.3.1 Recalling Off-site Backups
An offsite backup is stored in a remote location, such as a secure storage facility, and cannot be restored unless the media manager retrieves the media.
Some media managers provide status information to RMAN about which backups are off-site. Off-site backups are marked as AVAILABLE
in the RMAN repository even though the media must be retrieved from storage before the backup can be restored. If RMAN attempts to restore an off-site backup, then the restore job fails.
To recall offsite backups:
16.2.4 Validating Backups Before Restoring Them
Validating backups determines if the backups are usable.
Although the output of a restore preview operation indicates which backups will be restored, the usability of the backups is not actually verified. You can run RMAN commands to test the availability of usable backups for any RESTORE
operation, or test the contents of a specific backup for use in RESTORE
operations. The contents of the backups are actually read and checked for corruption.
Use one of the following validation options:
-
RESTORE
...
VALIDATE
to test whether RMAN can restore a specific object from a backup. RMAN chooses which backups to use. -
VALIDATE BACKUPSET
to test the validity of a backup set that you specify.See Also:
16.2.5 Restoring Archived Redo Logs Needed for Recovery
RMAN restores archived redo log files from backup automatically as needed to perform recovery.
You can also restore archived redo logs manually to save the time needed to restore these files later during the RECOVER
command, or if you want to store the restored archived redo log files in some new location. RMAN also gives you the flexibility of restoring all archive redo log files, the current ones, or archive redo log files from a specified previous incarnation of the database.
In case of missing archived redo logs during disaster recovery, RMAN enables you to automate the database recovery till the last available archived redo log, using the UNTIL AVAILABLE REDO
option. You can use this option only when performing recovery for a whole database. Using this option for a data file, tablespace, or pluggable database is not supported. To perform point-in-time recovery for a pluggable database, you must provide the SCN number as the point of recovery.
By default, RMAN restores archived redo logs with names constructed using the LOG_ARCHIVE_FORMAT
and the highest LOG_ARCHIVE_DEST_
n
parameters of the target database. These parameters are combined in a platform-specific fashion to form the name of the restored archived log.
This section contains the following topics:
16.2.5.1 Restoring Archived Redo Logs to a New Location
RMAN enables you to override the default location for restored archived redo log files.
The SET ARCHIVELOG DESTINATION
command manually stages archived logs to different locations while a database restore operation is occurring. During recovery, RMAN knows where to find the newly restored archived logs; it does not require them to be in the location specified in the initialization parameter file.
To restore archived redo logs to a new location:
-
Start RMAN and connect to a target database, as described in "Making Database Connections with RMAN".
-
Ensure that the database is mounted or open.
-
Perform the following operations within a
RUN
command:-
Specify the new location for the restored archived redo logs using
SET
ARCHIVELOG
DESTINATION
. -
Either explicitly restore the archived redo logs or execute commands that automatically restore the logs.
The following sample
RUN
command explicitly restores all backup archived logs to a new location:RUN { SET ARCHIVELOG DESTINATION TO '/oracle/temp_restore'; RESTORE ARCHIVELOG ALL; # restore and recover data files as needed . . . }
The following example sets the archived log destination and then uses
RECOVER DATABASE
to restore archived logs from this destination automatically:RUN { SET ARCHIVELOG DESTINATION TO '/oracle/temp_restore'; RESTORE DATABASE; RECOVER DATABASE; # restores and recovers logs automatically }
-
16.2.5.2 Restoring Archived Redo Logs to Multiple Locations
To manage disk space that is used to contain the restored logs, you can specify restore destinations for archived logs multiple times in one RUN
block, to distribute restored logs among several destinations.
Note that you cannot specify multiple destinations simultaneously to produce multiple copies of the same log during the restore operation.
The following example restores 300 archived redo logs from backup, distributing them across the directories /fs1/tmp
, /fs2/tmp
, and /fs3/tmp
:
RUN { # Set a new location for logs 1 through 100. SET ARCHIVELOG DESTINATION TO '/fs1/tmp'; RESTORE ARCHIVELOG FROM SEQUENCE 1 UNTIL SEQUENCE 100; # Set a new location for logs 101 through 200. SET ARCHIVELOG DESTINATION TO '/fs2/tmp'; RESTORE ARCHIVELOG FROM SEQUENCE 101 UNTIL SEQUENCE 200; # Set a new location for logs 201 through 300. SET ARCHIVELOG DESTINATION TO '/fs3/tmp'; RESTORE ARCHIVELOG FROM SEQUENCE 201 UNTIL SEQUENCE 300; # restore and recover data files as needed . . . }
When you issue a RECOVER
command, RMAN finds the needed restored archived logs automatically across the destinations to which they were restored, and applies them to the data files.
16.2.6 Providing the Password Required to Decrypt Encrypted Backups
For backups encrypted using certain techniques, you must provide the password that will be used to decrypt these backups.
-
Backups that were encrypted using transparent encryption with an auto-login keystore require no intervention to restore, if the keystore is available. RMAN decrypts these backups while restoring their contents.
-
For backups that were encrypted using transparent encryption with a password-protected software keystore, the keystore must be available and the keystore password must be provided before the restore operation is performed. Use the
SET
command with theDECRYPTION WALLET OPEN IDENTIFIED BY
option to specify the password that must be used to open the password-based software keystore.The following command sets the keystore password for a password-based software keystore (where
password
is a placeholder for the actual password that you enter):SET DECRYPTION WALLET OPEN IDENTIFIED BY password;
If a user with the
SYSBACKUP
privilege is performing the recovery, and a password-protected keystore is used, grant theSYSKM
privilege to this user. -
Backups created using password-mode encryption require the correct password to be entered before they can be restored. Use the
SET DECRYPTION
command to specify the password used to decrypt the backups. If you are restoring from a group of backups that were created with different passwords, then specify all of the required passwords on theSET DECRYPTION
command. RMAN automatically uses the correct password with each backup set. TheSET
command must be used before executing theRESTORE
andRECOVER
commands.The following command sets the password used to decrypt backups (where
password
is a placeholder for the actual password that you enter):SET DECRYPTION IDENTIFIED BY password;
See Also:
Oracle Database Backup and Recovery Reference for additional information about performing restore operations using encrypted backups
16.3 Performing Complete Database Recovery
RMAN and Oracle Enterprise Manager Cloud Control (Cloud Control) provide full support for backup and recovery of whole multitenant container database (CDB), only the root, or one or more pluggable databases (PDBs).
During complete recovery RMAN restores one or more data files and then applies all the redo generated after the restored backup.
16.3.1 About Complete Database Recovery
You use the RESTORE
and RECOVER
commands to restore and recover the database.
During the recovery, RMAN automatically restores backups of any needed archived redo logs. If backups are stored on a media manager, then channels must be configured in advance or a RUN
block with ALLOCATE CHANNEL
commands must be used to enable access to backups stored there.
If RMAN restores archived redo logs to the fast recovery area during a recovery, then it automatically deletes the restored logs after applying them to the data files. Otherwise, you can use the DELETE ARCHIVELOG
command to delete restored archived redo logs from disk when they are no longer needed for recovery. For example, you can enter the following command:
RECOVER DATABASE DELETE ARCHIVELOG;
16.3.1.1 About Restoring Data Files to a Nondefault Location
If you cannot restore data files to their default locations, then you must update the control file to reflect the new locations of the data files.
Use the RMAN SET NEWNAME
command within a RUN
command to specify the new file name. Afterward, use a SWITCH
command
to update the names of the data files in the control file. SWITCH DATAFILE
ALL
updates the control file to reflect the new names for all data files
for which a SET NEWNAME
has been issued in a RUN
command.
See Also:
Oracle Database Backup and
Recovery Reference for SWITCH
syntax
16.3.2 Performing Complete Recovery of a Whole CDB
When you recover a whole CDB, you recover the root and all PDBs in a single operation.
After restore and recovery of a whole database, when the database is open,
missing temporary tablespaces that were recorded in the control file are re-created with
their previous creation size, AUTOEXTEND
, and MAXSIZE
attributes. Only temporary tablespaces that are missing are re-created. If a temp file
exists at the location recorded in the RMAN repository but has an invalid header, then RMAN
does not re-create the temp file.
If the temp files were created as Oracle-managed files, then they are
re-created in the current DB_CREATE_FILE_DEST
location. Otherwise, they are
re-created at their previous locations. If RMAN cannot re-create the file due to an I/O
error or some other cause, then the error is reported in the alert log and the database open
operation continues.
See Also:
"Scope of This Chapter" for some of the assumptions used in the recovery procedures
To recover a whole CDB:
-
Complete the preparation steps that are required for your scenario, as described in "Preparing for Complete Database Recovery".
-
Start RMAN and connect to the root as a common user with the
SYSDBA
orSYSBACKUP
privilege, as described in "Connecting as Target to the Root". Connect to a recovery catalog (if used).RMAN displays the database status when it connects:
not started
,not mounted
,not open
(when the database is mounted but not open), ornone
(when the database is open). -
If the database is not mounted, then mount but do not open the database. Use the following command:
STARTUP MOUNT;
-
Use the
SHOW
command to see which channels are preconfigured.If the necessary devices and channels are configured, then no action is necessary. Otherwise, you can use the
CONFIGURE
command to configure automatic channels, or includeALLOCATE CHANNEL
commands within aRUN
block. -
Restore and recover the database. This procedure assumes that a fast recovery area is being used.
Do one of the following:
-
If you are restoring all data files to their original locations, then execute
RESTORE DATABASE
andRECOVER DATABASE
sequentially at the RMAN prompt.For example, enter the following commands if automatic channels are configured:
RESTORE DATABASE; RECOVER DATABASE;
If you manually allocate channels, then you must issue the
RESTORE
andRECOVER
commands together within aRUN
block as shown in the following example:RUN { ALLOCATE CHANNEL c1 DEVICE TYPE sbt; RESTORE DATABASE; RECOVER DATABASE; }
-
If you are restoring some data files to new locations, then execute
RESTORE DATABASE
andRECOVER DATABASE
sequentially in aRUN
command. Use theSET NEWNAME
command to rename data files.The following example restores the database, specifying new names for three of the data files, and then recovers the database:
RUN { SET NEWNAME FOR DATAFILE 2 TO '/disk2/df2.dbf'; SET NEWNAME FOR DATAFILE 3 TO '/disk2/df3.dbf'; SET NEWNAME FOR DATAFILE 4 TO '/disk2/df4.dbf'; RESTORE DATABASE; SWITCH DATAFILE ALL; RECOVER DATABASE; }
-
-
Examine the output to see if media recovery was successful. If so, open the database.
For example, enter the following command:
ALTER DATABASE OPEN;
16.3.3 Performing Complete Recovery of the Root
You might consider recovering only the root if a data corruption or user error occurs that affects only the root.
However, Oracle strongly recommends that you recover all PDBs after recovering the root to prevent metadata inconsistencies among the root and the PDBs. In this case, it might be preferable to perform a complete recovery of the whole CDB.
See Also:
"Scope of This Chapter" for some of the assumptions used in the recovery procedures
To recover the root:
-
Complete the preparation steps that are required for your recovery scenario, as described in "Preparing for Complete Database Recovery".
-
Start RMAN and connect to the root as a common user with the
SYSDBA
orSYSBACKUP
privilege, as described in "Connecting as Target to the Root". -
Place the CDB in mounted mode.
SHUTDOWN IMMEDIATE; STARTUP MOUNT;
-
(Optional) Use the
CONFIGURE
command to configure the default device type and automatic channels. -
Restore and recover the root with the following commands:
RESTORE DATABASE ROOT; RECOVER DATABASE ROOT;
-
Examine the output to see if media recovery was successful. If so, proceed to the next step.
-
(Strongly recommended) Recover all PDBs, including the CDB seed.
-
Issue the
RESTORE PLUGGABLE DATABASE
andRECOVER PLUGGABLE DATABASE
commands.The following example recovers the PDBs
sales
andhr
:RESTORE PLUGGABLE DATABASE 'PDB$SEED', sales, hr; RECOVER PLUGGABLE DATABASE 'PDB$SEED', sales, hr;
-
Examine the output to see if media recovery was successful. If so, proceed to the next step.
-
-
Open the CDB and all PDBs.
ALTER DATABASE OPEN; ALTER PLUGGABLE DATABASE ALL OPEN;
16.3.4 Performing Complete Recovery of a Tablespace in a CDB
Use the RESTORE
and RECOVER
commands with
the TABLESPACE
option to perform complete recovery of a tablespace in the CDB
root.
Scope of This Chapter for some of the assumptions used in the recovery procedures
In the basic scenario, the database is open, and some but not all of the data files are damaged. You want to restore and recover the damaged tablespace while leaving the database open so that the rest of the database remains available. This scenario assumes that database TRGT
has lost tablespace USERS
.
To restore and recover a tablespace in the root:
16.3.5 Performing Complete Recovery of PDBs with RMAN
You can perform complete recovery of one or more PDBs without affecting operations of other open PDBs.
See Also:
"Scope of This Chapter" for some of the assumptions used in the recovery procedures
There are two approaches to recovering a PDB with RMAN:
-
Connect to the root and then use the
RESTORE PLUGGABLE DATABASE
andRECOVER PLUGGABLE DATABASE
commands. This approach enables you to recover multiple PDBs with a single command. -
Connect to the PDB and use the
RESTORE DATABASE
andRECOVER DATABASE
commands. This approach recovers only a single PDB and enables you to use the same commands used for recovering databases.
To recover one or more PDBs while connected to the root:
-
Complete the preparation steps that are required for your recovery scenario, as described in "Preparing for Complete Database Recovery".
-
Start RMAN. Connect to the root as a common user with the
SYSDBA
orSYSBACKUP
privilege and to a recovery catalog (if used), as described in "Connecting as Target to the Root". -
Close the PDBs that you want to recover.
ALTER PLUGGABLE DATABASE sales, hr CLOSE;
If any data files are missing, an error occurs and you cannot close a PDB. You must then connect to the PDB to which the missing data file belongs, take the missing data file offline, and then close the PDB.
The following command takes the data file 12 offline:
ALTER PLUGGABLE DATABASE DATAFILE 12 OFFLINE;
Note:
If the data files that store the
SYSTEM
tablespace of a PDB are missing, then follow the recovery steps that are described in "Performing Complete Recovery of Tablespaces or Data Files in a PDB with RMAN". -
(Optional) Use the
CONFIGURE
command to configure the default device type and automatic channels. -
Issue the
RESTORE PLUGGABLE DATABASE
andRECOVER PLUGGABLE DATABASE
commands.The following example recovers the CDB seed,
PDB$SEED
, and the PDBssales
andhr
:RESTORE PLUGGABLE DATABASE 'pdb$seed', sales, hr; RECOVER PLUGGABLE DATABASE 'pdb$seed', sales, hr;
-
If any data files were taken offline in Step 2, make these data files online.
Connect to the PDB to which the missing data file belongs and then make the data file online. The following command makes the data file 12 online:
ALTER DATABASE DATAFILE 12 ONLINE;
-
Examine the output to see if media recovery was successful. If so, open the PDBs.
ALTER PLUGGABLE DATABASE sales, hr OPEN;
To connect to and recover one PDB:
16.3.6 Performing Complete Recovery of PDBs with Cloud Control
Enterprise Manager Cloud Control (Cloud Control) provides an interface to recover PDBs.
To recover one or more PDBs with Cloud Control:
-
From the Database Home page, select Backup & Recovery from the Availability menu, and then select Perform Recovery.
-
If you have not logged in to the database previously, the Database Login page is displayed. Log in to the database using Named or New credentials and then click Login.
Cloud Control displays the Perform Recovery page.
-
From the User Directed Recovery section, select Pluggable Databases from the Recovery Scope drop-down list, and then click Recover.
The Perform Pluggable Database Recovery Wizard appears and displays the Pluggable Databases page.
-
Select the PDBs that you want to recover by following these steps:
-
Click Add to display the Available Pluggable Databases page.
-
From the list of PDBs shown, click in the Select column to designate the PDBs that you want to recover. Optionally, you can click Select All to turn on the Select option for all available PDBs. Click Select None to deselect all PDBs.
-
Click the Select button to return to the Pluggable Databases page.
-
Optionally, you can remove PDBs from the table by clicking in the Select column for each PDB that you want to remove and then clicking Remove.
-
-
Complete the wizard by navigating through the remainder of the pages to recover the PDBs. For more information about each page of the wizard, click Help.
16.3.7 Performing Complete Recovery of Tablespaces or Data Files in a PDB with RMAN
Because tablespaces in different PDBs can have the same name, to eliminate ambiguity, you must connect directly to a PDB to recover one or more of its tablespaces. In contrast, because data file numbers and paths are unique across the CDB, you can connect either to the root or to a PDB when recovering PDB data files.
If you connect to the root, you can recover data files from multiple PDBs with a single command. If you connect to a PDB, you can recover only data files in that PDB.
To restore and recover a non-SYSTEM tablespace in a PDB:
-
Complete the preparation steps that are required for your recovery scenario, as described in "Preparing for Complete Database Recovery".
-
Start RMAN. Connect to a target database and to a recovery catalog (if used), as described in "Making Database Connections with RMAN."
-
If the database is open, then take the tablespace requiring recovery offline.
For example, enter the following command to take the
USERS
tablespace offline:ALTER TABLESPACE users OFFLINE IMMEDIATE;
-
Use the
SHOW
command to see which channels are preconfigured.If the necessary devices and channels are configured, then no action is necessary. Otherwise, you can use the
CONFIGURE
command to configure automatic channels, or includeALLOCATE CHANNEL
commands within aRUN
block. -
Restore and recover the tablespace. Do one of the following:
-
If you are restoring data files to their original locations, then run the
RESTORE TABLESPACE
andRECOVER TABLESPACE
commands at the RMAN prompt.For example, enter the following commands if automatic channels are configured:
RMAN> RESTORE TABLESPACE users; RMAN> RECOVER TABLESPACE users;
-
If you are restoring some data files to new locations, then execute
RESTORE TABLESPACE
andRECOVER TABLESPACE
in aRUN
command. Use theSET NEWNAME
command to rename data files.
-
-
Examine the output to see if recovery was successful. If so, bring the recovered tablespace back online.
For example, enter the following command:
ALTER TABLESPACE users ONLINE;
To restore and recover the SYSTEM tablespace in a PDB:
-
Complete the preparation steps that are required for your recovery scenario, as described in "Preparing for Complete Database Recovery".
-
Start RMAN. Connect to the root as a common user with the
SYSDBA
orSYSBACKUP
privilege and to a recovery catalog (if used), as described in "Connecting as Target to the Root". -
Shut down the CDB and restart it in mount mode.
SHUTDOWN IMMEDIATE; STARTUP MOUNT;
-
Restore and recover the data files that store the
SYSTEM
tablespace of the affected PDB.RESTORE DATAFILE 2,3; RECOVER DATAFILE 2,3;
-
Open all the PDBs in the CDB.
ALTER PLUGGABLE DATABASE ALL OPEN READ WRITE;
To recover non-SYSTEM data files in a PDB:
16.3.8 Performing Complete Recovery of Tablespaces in a PDB with Cloud Control
Oracle Enterprise Manager Cloud Control (Cloud Control) provides an interface to recover tablespaces within a PDB.
To perform complete recovery of tablespaces in a PDB with Cloud Control:
-
From the Database Home page, select Backup & Recovery from the Availability menu, and then select Perform Recovery.
-
If you have not logged in to the database previously, the Database Login page is displayed. Log in to the database using Named or New credentials and then click Login.
Cloud Control displays the Perform Recovery page.
-
From the User Directed Recovery section, select Tablespaces from the Recovery Scope drop-down list, and then click Recover.
-
On the Perform Object Level Recovery:Point-in-time page, ensure that Recover to the current time is selected, and click Next.
-
On the Perform Object Level Recovery: Tablespaces page, select the tablespaces that you want to recover by completing these steps:
-
Click Add to display the Available Tablespaces page.
The Search Results table shows all available tablespaces and includes the name of the PDB to which each tablespace belongs.
-
Click Select to designate the tablespaces that you want to recover. Optionally, you can click Select All to turn on the Select option for all available tablespaces. Click Select None to deselect all tablespaces.
-
Click the Select button to return to the Perform Object Level Recovery: Tablespaces page.
-
Optionally, you can remove tablespaces from the table by turning on the Select option for each tablespace that you want to remove and then clicking Remove.
-
-
Click Next to move to the next step in the wizard.
-
Complete the wizard by navigating through the remainder of the pages to recover the PDB tablespace. For more information about each page of the wizard, click Help.
16.3.9 Performing Complete Recovery After Switching to a Copy
You can recover a database by switching to image copies of inaccessible data files. This technique takes less time than traditional restore and recovery because no backups need to be restored.
If you have image copies of the inaccessible data files in the fast recovery area, then you can use the SWITCH DATAFILE ... TO COPY
command to point the control file at the data file copy and then use RECOVER
to recover lost changes. You can also use the SWITCH DATABASE TO COPY
command to point the control file at a copy of the whole database.
Note:
A SWITCH TABLESPACE ... TO COPY
command is also supported for cases when all data files in a tablespace are lost and copies of all data files exist. The same restriction exists for SWITCH DATABASE ... TO COPY
.
16.3.9.1 Performing Recovery After Switching to a Data File Copy
When one or more data files are damaged, you can perform recovery by switching to existing image copies of the damaged data files.
"Scope of This Chapter" for some of the assumptions used in the recovery procedures
In the basic scenario, the database is open, and some but not all of the data files are damaged. During the course of the day, a data file goes missing due to storage failure. You must repair this file, but cannot afford the time to do a restore and recovery from a backup. You decide to use a recent image copy backup as the new file, thus eliminating restore time. This scenario assumes that database trgt
has lost data file 4.
To switch to a data file copy and perform recovery:
16.3.9.2 Performing Complete Recovery After Switching to a Database Copy
You can perform complete database recovery by switching to image copies of the damaged data files instead of restoring these data files.
"Scope of This Chapter" for some of the assumptions used in the recovery procedures
In this scenario, the database is shut down, and all of the data files are damaged. You have image copies of all the damaged data files and decide to use the existing image copies as the new data files, thus eliminating restore time.
To switch to a database copy and perform recovery:
16.4 Performing Complete Recovery Using Preplugin Backups
Use the RECOVER
command to perform complete recovery using preplugin backups.
This section contains the following topics:
16.4.1 About Complete Recovery of PDBs Using PrePlugin Backups
Preplugin backups are used to restore and recover a PDB to its state at a time in the past that was before the PDB was plugged in to the current CDB.
To perform complete recovery using preplugin backups, use the FROM PREPLUGIN
clause of the RESTORE
and RECOVER
commands. RMAN restores data files using preplugin backups and then uses the preplugin incremental backups and archived redo logs to recover data files to a point in time that is before the PDB was plugged in to the destination CDB.
The metadata for the preplugin backups is migrated to the destination CDB when you unplug the PDB or use the DBMS_PDB.EXPORTRMANBACKUP()
procedure with non-CDBs. Preplugin backups are not automatically migrated to the destination CDB. You must ensure that the destination CDB has access to the backups created on the source database.
The location to which RMAN restores preplugin archived redo logs depends on whether a fast recovery area is configured in the destination CDB. If a fast recovery area is not the default destination for archived redo log files in the CDB, then RMAN restores preplugin archived redo logs to the fast recovery area. If the fast recovery area is the default destination for archived redo log files in the CDB, then you must use the SET ARCHIVELOG DESTINATION
command to specify a location for the preplugin archived redo log files.
16.4.2 Performing Complete Recovery of PDBs Using Preplugin Backups
RMAN performs complete recovery of a PDB using preplugin backups. These preplugin backups were created on a source non-CDB or a source CDB before the PDB was migrated to the current target CDB.
Note:
You cannot recover a PDB using preplugin backups if the preplugin backup was created before the PDB was opened with the RESETLOGS
option.
To perform complete recovery of a PDB using preplugin backups:
16.4.3 Example: Performing Complete Recovery of PDBs Using Preplugin Backups
This example performs complete recovery of a PDB my_pdb
in the destination CDB prod_cdb
using preplugin backups.
The PDB my_pdb
was unplugged from the CDB test_cdb
and then plugged in to the CDB prod_cdb
. When this PDB was unplugged from test_cdb
, its metadata was stored in the file mypdb.xml
. This metadata was used to plug my_pdb
into prod_cdb
. The backups of my_pdb
that were created in the source CDB test_cdb
are stored in the shared location /oracle/database/backups
. The CDB prod_cdb
uses the fast recovery area to store archived redo log files.
16.5 Performing Complete Recovery of Application Containers
RMAN enables you to use the RESTORE
and RECOVER
commands to perform complete recovery of the application containers without impacting the other containers in the CDB.
16.5.1 Performing Complete Recovery of the Application Root
Use the RESTORE
and RECOVER
commands to perform complete recovery of the application root.
COMPATIBLE
parameter for the CDB must be set to 19.0 or higher.
To recover the application root when connected to the root in a CDB
See Also:
16.5.2 Performing Complete Recovery of the Application Root and Application PDBs
You can perform complete recovery of an application container, which includes the application root and all its application PDBs without impacting the other PDBs within the CDB.
COMPATIBLE
parameter for the CDB must be set to 12.2 or higher.
To perform complete recovery of the application root and all its application PDBs:
See Also:
16.6 Performing Complete Recovery of Sparse Databases with RMAN
You can recover sparse databases to the most recent point in time using the RESTORE
and RECOVER
commands.
Note:
The base (read-only) data files in a sparse database are not encrypted. Ensure that the base data files are stored in a protected storage and accessed using secured communications.
16.6.1 Performing Complete Recovery of a Sparse CDB
Performing complete recovery of a CDB containing is very similar to performing the complete recovery of a database.
RMAN first restores the logical data that was backed up from the delta storage space of the database and then recovers the database by reading from the redo log and applying the logical data file blocks. You can perform either complete recovery or point-in-time recovery of a sparse database, tablespace, or data file.
To recover a sparse CDB:
16.6.2 Performing Recovery of a Sparse PDB with RMAN
You can recover a sparse PDB while you are connected at the root level or at the CDB level.
To recover one or more sparse PDBs while connected to the root:
-
Complete the preparation steps required for your recovery scenario, as described in "Preparing for Complete Database Recovery".
-
Start RMAN and connect to the root as a common user with the
SYSDBA
orSYSBACKUP
privilege, as described in "Making Database Connections with RMAN". -
Close the PDBs that you want to recover.
ALTER PLUGGABLE DATABASE sales, hr CLOSE;
If any data files are missing, an error occurs and you cannot close a PDB. You must then connect to the PDB to which the missing data file belongs, take the missing data file offline, and then close the PDB.
The following command takes the data file 12 offline:
ALTER PLUGGABLE DATABASE DATAFILE 12 OFFLINE;
Note:
If the data files that store the
SYSTEM
tablespace of a PDB are missing, then follow the recovery steps described in "Performing Complete Recovery of Tablespaces or Data Files in a PDB with RMAN". -
(Optional) Use the
CONFIGURE
command to configure the default device type and automatic channels. -
Run the
RESTORE
andRECOVER
commands for the pluggable database.The following example performs complete recovery of the PDBHR_PDB
when connected to the root:RESTORE FROM SPARSE PLUGGABLE DATABASE HR_PDB; RECOVER PLUGGABLE DATABASE HR_PDB;
To connect to and recover one sparse PDB: