Database Backup and Recovery
Most of database systems have incorporated backup and recovery tools into their interfaces and infrastructure it is a good idea to understand what the backup and recovery process involves, beyond the work flow of using the tools. With the growing dependency in the workplace on information and general, and the information in your database specifically, there has never been a time when safe backups and reliable recoveries were more important. Are you maintaining your databases properly? Do they participate in a backup and recovery routine that checks on the health of the data? If you are not 100% sure of this, then you need to find out.Database Backup and Recovery Needs
It is not just the data files that need to be part of the backup process. You must also backup the transaction logs of the database as well. Without the transaction logs the data files are useless in a recovery event. How often you choose to perform these backup routines is really dependent on the data requirements of your company. If you do not know what those are then you need to find out either by referring to them or asking for them to be created through a research and investigation process.
Backup and Recovery and Database Failure
Failure can happen for any number of reasons. There are three main ones that recur enough to be worth incorporating into your backup and recovery plan. User error is the number one reason for data damage, loss, or corruption. Included in this type of failure is an application modifying or destroying the data on its own or through a user choice. Recovery and restore to the point in time before the corruption occurred.
This returns the data to a clean position at the cost of any other changes that were being made to the data since the point the corruption took place. Any lost work will need to be re-entered or processes repeated if necessary.
Media failure can also cause data loss or damage. Media failure can happen when the media the data files or transaction logs are stored on fail. Most databases will be stored on computer hard drives or across groups of hard drives on designated servers. Hard drives are mechanical devices, just like automobiles, and are made up of parts and pieces that work together. Mechanical devices are known for failure and will need to be replaced once, or if, the data has been retrieved from them.
Backup and Recovery and Disaster
The third reason for database failure is a disastrous or catastrophic event. This can be in the form of fire, flood, or any naturally occurring storm. It can also happen through electrical outage, a virus, or the deliberate hacking of your data. Any of these can corrupt or cause the loss of your data. The true disaster will be the lack of data backup and or the lack of a recovery plan. Without data backup recovery is impossible. And without a recovery plan there is no guarantee that your data backup will make it through the recovery process.Purpose of Complete Database Recovery
This chapter assumes that some or all of your datafiles 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.
Scope of This Chapter
This chapter explain how to use complete recovery to fix the most common database problems. This chapter makes the following assumptions:
You have lost some or all datafiles 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 datafile backups. Every datafile either has a backup, or a complete set of online and archived redo logs goes back to the creation of a datafile with no backup.
RMAN can handle lost datafiles without user intervention during restore and recovery. When a datafile is lost, the possible cases can be classified as follows:
The control file knows about the datafile, that is, you backed up the control file after datafile creation, but the datafile itself is not backed up. If the datafile record is in the control file, then
RESTOREcreates the datafile in the original location or in a user-specified location. TheRECOVERcommand can then apply the necessary logs to the datafile.The control file does not have the datafile record, that is, you did not back up the control file after datafile creation. During recovery, the database will detect the missing datafile and report it to RMAN, which will create a new datafile and continue recovery by applying the remaining logs. If the datafile was created in a parent incarnation, then it will be 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 wallet must be open when performing media recovery of this tablespace. See Oracle Database Administrator's Guide to learn about encrypted tablespaces.
Your database runs in a single-instance configuration.
While 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.
Enterprise Manager provides access to RMAN through a set of wizards. These wizards lead you through a variety of recovery procedures based on an analysis of your database, your available backups, and your data recovery objectives.
By using Enterprise Manager, you can perform the simpler restore and recovery scenarios outlined in this chapter. You can also use more sophisticated restore and recovery techniques such as point-in-time recovery and database flashback, which allow for efficient repair of media failures and user errors. In most cases, using Enterprise Manager is simpler than using the RMAN command-line client directly
Preparing for Complete Database Recovery
While RMAN simplifies most database restore and recovery tasks, you must still plan your database restore and recovery strategy based on which database files have been lost and your recovery goal. This section contains the following topics:
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.
Identifying a Lost Control File
It is usually obvious when the control file of your database is lost. The database shuts down immediately when any of the multiplexed control files becomes inaccessible. Also, the database reports an error if you try to start it without a valid control file at each location specified in the CONTROL_FILES initialization parameter.
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 datafiles need to be restored. This technique is described in "Performing Recovery with a Backup Control File".
Identifying Datafiles Requiring Media Recovery
When and how to recover depends on the state of the database and the location of its datafiles.
Identifying Datafiles with RMAN
An easy technique for determining which datafiles are missing is to run a VALIDATE DATABASE command, which attempts to read all specified datafiles. For example, start the RMAN client and run the following commands to validate the database (sample output included).
Example 17-1 BACKUP VALIDATE DATABASE
RMAN> VALIDATE DATABASE;
Starting validate at 20-OCT-06
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 10/20/2007 13:05:43
RMAN-06056: could not access datafile 7
The output in Example 17-1 indicates that datafile 7 is inaccessible. You can then run the REPORT SCHEMA command to obtain the tablespace name and filename for datafile 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
Identifying Datafiles with SQLAlthough 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 datafiles require media recovery:
Start SQL*Plus and connect to the target database instance. For example, issue the following commands to connect to
trgt:% sqlplus
SQL> CONNECT SYS/password@trgt AS SYSDBADetermine the status of the database by executing the following SQL query:
SELECT STATUS FROM V$INSTANCE;
If the status is
OPEN, then the database is open. Nevertheless, some datafiles may require media recovery.Query
V$DATAFILE_HEADERto determine the status of your datafiles. Run the following SQL statements to check the datafile headers:COL FILE# FORMAT 999
COL STATUS FORMAT A7
COL ERROR FORMAT A10
COL TABLESPACE_NAME FORMAT A10
COL NAME FORMAT A30
SELECT FILE#, STATUS, ERROR, RECOVER, TABLESPACE_NAME, NAME
FROM V$DATAFILE_HEADER
WHERE RECOVER = 'YES'
OR (RECOVER IS NULL AND ERROR IS NOT NULL);Each row returned represents a datafile that either requires media recovery or has an error requiring a restore. Check the
RECOVERandERRORcolumns.RECOVERindicates whether a file needs media recovery, andERRORindicates whether there was an error reading and validating the datafile header.If
ERRORis notNULL, then the datafile header cannot be read and validated. Check for a temporary hardware or operating system problem causing the error. If there is no such problem, you must restore the file or switch to a copy.If the
ERRORcolumn isNULLand theRECOVERcolumn isYES, then the file requires media recovery (and may also require a restore from backup).Optionally, query
V$RECOVER_FILEto list datafiles requiring recovery by datafile number with their status and error information. For example, execute the following query:SELECT FILE#, ERROR, ONLINE_STATUS, CHANGE#, TIME
FROM V$RECOVER_FILE;Note:
You cannot useV$RECOVER_FILEwith a control file restored from backup or a control file that was re-created after the time of the media failure affecting the datafiles. A restored or re-created control file does not contain the information needed to updateV$RECOVER_FILEaccurately.To find datafile and tablespace names, you can also perform useful joins using the datafile number and the
V$DATAFILEandV$TABLESPACEviews. For example:COL DF# FORMAT 999
COL DF_NAME FORMAT A35
COL TBSP_NAME FORMAT A7
COL STATUS FORMAT A7
COL ERROR FORMAT A10
COL CHANGE# FORMAT 99999999
SELECT r.FILE# AS df#, d.NAME AS df_name, t.NAME AS tbsp_name,
d.STATUS, r.ERROR, r.CHANGE#, r.TIME
FROM V$RECOVER_FILE r, V$DATAFILE d, V$TABLESPACE t
WHERE t.TS# = d.TS#
AND d.FILE# = r.FILE#;The
ERRORcolumn identifies the problem for each file requiring recovery.
Determining the DBID of the Database
In situations requiring the recovery of your server parameter file or control file from autobackup, you need to know the DBID. You should 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 filename 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 filename.
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 11.1.0.6.0 - Production on Wed Jul 11 17:51:30 2007
Copyright (c) 1982, 2007, Oracle. All rights reserved.
connected to target database: PROD (DBID=36508508
Previewing Backupa Used in Restore Operations
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, as well as 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:
Run a
RESTOREcommand with thePREVIEWoption.For example, run one of the following commands:
RESTORE DATABASE PREVIEW;
RESTORE ARCHIVELOG FROM TIME 'SYSDATE-7' PREVIEW;If the report produced by
RESTORE...PREVIEWprovides too much information, then specify theSUMMARYoption as shown in the following example:RESTORE DATABASE PREVIEW SUMMARY;
If satisfied with the output, then stop here. If the output indicates that RMAN will request a backup from a tape that you know is temporarily unavailable, then continue with this procedure. If the output indicates that a backup is stored offsite, then skip to "Recalling Offsite Backups".
If needed, use the
CHANGEcommand to set the backup status of any temporarily unavailable backups toUNAVAILABLE."Updating a Backup to Status AVAILABLE or UNAVAILABLE" explains how to perform this task.
Optionally, run
RESTORE...PREVIEWagain to confirm that the restore will not attempt to use unavailable backups.
Some media managers provide status information to RMAN about which backups are offsite. 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.
Offsite 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 a offsite backup, then the restore job fails.
You can use RESTORE ... PREVIEW to identify offsite backups. The command output indicates whether backups are stored offsite, as shown by the text at the end of the sample output in Example 17-2.
Example 17-2 RESTORE ... PREVIEW Output
List of Backup Sets
===================
BS Key Size Device Type Elapsed Time Completion Time
------- ---------- ----------- ------------ ---------------
9 2.25M SBT_TAPE 00:00:00 21-MAY-07
BP Key: 9 Status: AVAILABLE Compressed: NO Tag: TAG20070521T144258
Handle: 0aii9k7i_1_1 Media: 0aii9k7i_1_1
List of Archived Logs in backup set 9
Thrd Seq Low SCN Low Time Next SCN Next Time
---- ------- ---------- --------- ---------- ---------
1 1 392314 21-MAY-07 392541 21-MAY-07
1 2 392541 21-MAY-07 392545 21-MAY-07
1 3 392545 21-MAY-07 392548 21-MAY-07
1 4 392548 21-MAY-07 395066 21-MAY-07
1 5 395066 21-MAY-07 395095 21-MAY-07
1 6 395095 21-MAY-07 395355 21-MAY-07
List of remote backup files
============================
Handle: aii9k7i_1_1 Media: 0aii9k7i_1_1
validation succeeded for backup piece
Finished restore at 21-MAY-07
released channel: dev1
You can use RESTORE ... PREVIEW RECALL to instruct the media manager to make offsite backups available.
To recall offsite backups:
If backups are stored offsite, then execute a
RESTORE ... PREVIEWcommand with theRECALLoption.The following example initiates recall for the offsite archived log backups shown in Example 17-2 (sample output included):
RESTORE ARCHIVELOG ALL PREVIEW RECALL;
The following sample output indicates that RMAN initiated a recall:
List of Backup Sets
===================
BS Key Size Device Type Elapsed Time Completion Time
------- ---------- ----------- ------------ ---------------
9 2.25M SBT_TAPE 00:00:00 21-MAY-07
BP Key: 9 Status: AVAILABLE Compressed: NO Tag: TAG20070521T144258
Handle: VAULT0aii9k7i_1_1 Media: /tmp,VAULT0aii9k7i_1_1
List of Archived Logs in backup set 9
Thrd Seq Low SCN Low Time Next SCN Next Time
---- ------- ---------- --------- ---------- ---------
1 1 392314 21-MAY-07 392541 21-MAY-07
1 2 392541 21-MAY-07 392545 21-MAY-07
1 3 392545 21-MAY-07 392548 21-MAY-07
1 4 392548 21-MAY-07 395066 21-MAY-07
1 5 395066 21-MAY-07 395095 21-MAY-07
1 6 395095 21-MAY-07 395355 21-MAY-07
Initiated recall for the following list of remote backup files
==========================================================
Handle: VAULT0aii9k7i_1_1 Media: /tmp,VAULT0aii9k7i_1_1
validation succeeded for backup piece
Finished restore at 21-MAY-07
released channel: dev1Run the
RESTORE...PREVIEWcommand. If necessary, return to the previous step until no backups needed for the restore are reported as offsite.
Validating Backups Before Restoring Them
While the procedures in "Previewing Backups Used in Restore Operations" indicate which backups will be restored, they do not verify that the backups are actually usable. 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. You have the following validation options:
RESTORE...VALIDATEtests whether RMAN can restore a specific object from a backup. RMAN chooses which backups to use.VALIDATE BACKUPSETtests the validity of a backup set that you specify.
Restoring Archived Redo Logs Needed for Recovery
RMAN restore 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.
By default, RMAN restores archived redo logs with names constructed using the LOG_ARCHIVE_FORMAT and the LOG_ARCHIVE_DEST_1 parameters of the target database. These parameters are combined in a platform-specific fashion to form the name of the restored archived log.
Restoring Archived Redo Logs to a New Location
You can override the default location for restored archived redo logs with the SET ARCHIVELOG DESTINATION command. This command manually stages archived logs to different locations while a database restore 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:
After connecting to the target database, ensure the database is mounted or open.
Perform the following operations within a
RUNblock:Specify the new location for the restored archived redo logs using
SETARCHIVELOGDESTINATION.Either explicitly restore the archived redo logs or execute commands that automatically restore the logs.
The following example explicitly restores all backup archived logs to a new location:
RUN
{
SET ARCHIVELOG DESTINATION TO '/oracle/temp_restore';
RESTORE ARCHIVELOG ALL;
# restore and recover datafiles as needed
.
.
.
}The following example sets the archived log destination and then uses
RECOVER DATABASEto restore archived logs from this destination automatically:RUN
{
SET ARCHIVELOG DESTINATION TO '/oracle/temp_restore';
RESTORE DATABASE;
RECOVER DATABASE; # restores and recovers logs automatically
}
Restoring Archived Redo Logs to Multiple Locations
You can specify restore destinations for archived logs multiple times in one RUN block, in order to distribute restored logs among several destinations. (You cannot, however specify multiple destinations simultaneously to produce multiple copies of the same log during the restore operation.) You can use this feature to manage disk space used to contain the restored logs.
This 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 datafiles 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 datafiles.
Performing Complete Database Recovery
This section assumes that you have already performed the tasks in "Preparing for Complete Database Recovery". This section describes the basic outline of complete database recovery, which is intended to encompass a wide range of different scenarios.
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 flash recovery area during a recovery, then it automatically deletes the restored logs after they applying them to the datafiles. 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;
Restoring Datafiles to a Nondefault LocationIf you cannot restore datafiles to their default locations, then you must update the control file to reflect the new locations of the datafiles. Use the RMAN SET NEWNAME command within a RUN command to specify the new filename. Afterward, use a SWITCH command, which is equivalent to using the SQL statement ALTER DATABASE RENAME FILE, to update the names of the datafiles in the control file. SWITCH DATAFILE ALL updates the control file to reflect the new names for all datafiles for which a SET NEWNAME has been issued in a RUN command.
If RMAN is restoring encrypted backups, then RMAN automatically decrypts backup sets when their contents are restored. Transparently encrypted backups require no intervention to restore, as long as the encrypted wallet is open and available.
Password-encrypted backups require the correct password to be entered before they can be restored. You must enter the encryption password with the SET DECRYPTION command. If restoring from a group of backups that were created with different passwords, then specify all of the required passwords on the SET DECRYPTION command. RMAN will automatically use the correct password with each backup set.
Performing Complete Recovery of the Whole Database
This scenario assumes that database trgt has lost most or all of its datafiles. It also assumes that the database uses a flash recovery area.
Note: After restore and recovery of a whole database, when the database is opened, any missing temporary tablespaces 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 tempfile exists at the location recorded in the RMAN repository but has an invalid header, then RMAN does not re-create the tempfile.
If the tempfiles were originally 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 is unable to 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.
To restore and recover the whole database:
Start RMAN and connect to the target database.
For example, enter the following command:
% rman
RMAN> CONNECT SYS/password@trgtRMAN displays the database status when it connects:
not started,not mounted,not open(when mounted but not open), or none (database is open).If the database is not mounted, then mount but do not open the database.
For example, enter the following command:
STARTUP MOUNT;
Use the
SHOWcommand to see which channels are preconfigured.For example, enter the following command (sample output is included):
SHOW ALL;
RMAN configuration parameters for database with db_unique_name PROD1 are:
.
.
.
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DEVICE TYPE SBT_TAPE PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE CHANNEL DEVICE TYPE 'SBT_TAPE' PARMS "SBT_LIBRARY=/usr/local/oracle/backup/lib/libobk.so";If the necessary devices and channels are already configured, then no action is necessary. Otherwise, you can use the
CONFIGUREcommand to configure automatic channels, or includeALLOCATE CHANNELcommands within aRUNblock.If restoring password-protected encrypted backups, then specify the password.
Use the
SET DECRYPTION IDENTIFIED BYcommand to specify a password for password-protected backups. The following example specifies the passwordmypasswordto restore encrypted backups:SET DECRYPTION IDENTIFIED BY mypassword;
Restore and recover the database. Do one of the following:
If you are restoring all datafiles to their original locations, then execute
RESTORE DATABASEandRECOVER DATABASEsequentially at the RMAN prompt.For example, enter the following commands if automatic channels are configured (sample output included):
RMAN> RESTORE DATABASE;
Starting restore at 20-JUN-06
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=35 device type=DISK
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: SID=34 device type=SBT_TAPE
channel ORA_SBT_TAPE_1: Oracle Secure Backup
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00001 to /disk1/oracle/dbs/tbs_01.f
channel ORA_DISK_1: restoring datafile 00002 to /disk1/oracle/dbs/tbs_ax1.f
.
.
.
Finished restore at 20-JUN-06RMAN> RECOVER DATABASE;
Starting recover at 20-JUN-06
using channel ORA_DISK_1
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: SID=34 device type=SBT_TAPE
channel ORA_SBT_TAPE_1: Oracle Secure Backup
starting media recovery
channel ORA_DISK_1: starting archived log restore to default destination
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=5
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=6
.
.
.
channel ORA_DISK_1: reading from backup piece /disk1/oracle/work/orcva/TKRM/backupset/2007_06_20/o1_mf_annnn_TAG20070620T113128_29jhr197_.bkp
channel ORA_DISK_1: piece handle=/disk1/oracle/work/orcva/TKRM/backupset/2007_06_20/o1_mf_annnn_TAG20070620T113128_29jhr197_.bkp tag=TAG20070620T113128
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:02
archived log file name=/disk1/oracle/work/orcva/TKRM/archivelog/2007_06_20/o1_mf_1_5_29jhv47k_.arc thread=1 sequence=5
channel default: deleting archived log(s)
.
.
.
media recovery complete, elapsed time: 00:00:15
Finished recover at 20-JUN-06If you manually allocate channels, then you must issue the
RESTOREandRECOVERcommands together within aRUNblock as shown in the following example:RUN
{
ALLOCATE CHANNEL c1 DEVICE TYPE sbt;
RESTORE DATABASE;
RECOVER DATABASE;
}If you are restoring some datafiles to new locations, then execute
RESTORE DATABASEandRECOVER DATABASEsequentially in aRUNcommand. Use theSET NEWNAMEto rename datafiles, as described in "Restoring Datafiles to a Nondefault Location".The following example restores the database, specifying new names for three of the datafiles, 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;
Performing Complete Recovery of a Tablespace
In the basic scenario, the database is open, and some but not all of the datafiles 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 tbs_3.
To restore and recover a tablespace:
Start RMAN and connect to the target database.
For example, enter the following command:
% rman
RMAN> CONNECT SYS/password@trgtRMAN displays the database status when it connects:
not started,not mounted,not open(when mounted but not open), or none (database is open).If the database is open, then take the datafile requiring recovery offline.
For example, enter the following command to take
tbs_3offline:SQL "ALTER TABLESPACE tbs_3 OFFLINE IMMEDIATE";
Use the
SHOWcommand to see which channels are preconfigured.For example, enter the following command (sample output is included):
SHOW ALL;
RMAN configuration parameters for database with db_unique_name PROD1 are:
.
.
.
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DEVICE TYPE SBT_TAPE PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE CHANNEL DEVICE TYPE 'SBT_TAPE' PARMS "SBT_LIBRARY=/usr/local/oracle/backup/lib/libobk.so";If the necessary devices and channels are already configured, then no action is necessary. Otherwise, you can use the
CONFIGUREcommand to configure automatic channels, or includeALLOCATE CHANNELcommands within aRUNblock.If restoring password-protected backups, then specify the password.
Use the
SET DECRYPTION IDENTIFIED BYcommand to specify a password for password-protected backups. The following example specifies the passwordmypasswordto restore encrypted backups:SET DECRYPTION IDENTIFIED BY mypassword;
Restore and recover the tablespace. Do one of the following:
If you are restoring datafiles to their original locations, then run the
RESTORE TABLESPACEandRECOVER TABLESPACEcommands at the RMAN prompt.For example, enter the following command if automatic channels are configured (sample output included):
RMAN> RESTORE TABLESPACE tbs_3;
Starting restore at 20-JUN-06
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=37 device type=DISK
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: SID=38 device type=SBT_TAPE
channel ORA_SBT_TAPE_1: Oracle Secure Backup
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00012 to /disk1/oracle/dbs/tbs_31.f
channel ORA_DISK_1: restoring datafile 00013 to /disk1/oracle/dbs/tbs_32.f
channel ORA_DISK_1: restoring datafile 00021 to /disk1/oracle/dbs/tbs_33.f
channel ORA_DISK_1: reading from backup piece /disk1/oracle/work/orcva/TKRM/backupset/2007_06_20/o1_mf_nnndf_TAG20070620T105435_29jflwor_.bkp
channel ORA_DISK_1: piece handle=/disk1/oracle/work/orcva/TKRM/backupset/2007_06_20/o1_mf_nnndf_TAG20070620T105435_29jflwor_.bkp tag=TAG20070620T105435
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
Finished restore at 20-JUN-06RMAN> RECOVER TABLESPACE tbs_3;
Starting recover at 20-JUN-06
using channel ORA_DISK_1
using channel ORA_SBT_TAPE_1
starting media recovery
archived log for thread 1 with sequence 27 is already on disk as file /disk1/oracle/work/orcva/TKRM/archivelog/2007_06_20/o1_mf_1_27_29jjmtc9_.arc
archived log for thread 1 with sequence 28 is already on disk as file /disk1/oracle/work/orcva/TKRM/archivelog/2007_06_20/o1_mf_1_28_29jjnc5x_.arc
.
.
.
channel ORA_DISK_1: starting archived log restore to default destination
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=5
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=6
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=7
.
.
.
channel ORA_DISK_1: reading from backup piece /disk1/oracle/work/orcva/TKRM/backupset/2007_06_20/o1_mf_annnn_TAG20070620T113128_29jhr197_.bkp
channel ORA_DISK_1: piece handle=/disk1/oracle/work/orcva/TKRM/backupset/2007_06_20/o1_mf_annnn_TAG20070620T113128_29jhr197_.bkp tag=TAG20070620T113128
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:02
archived log file name=/disk1/oracle/work/orcva/TKRM/archivelog/2007_06_20/o1_mf_1_5_29jkdvjq_.arc thread=1 sequence=5
channel default: deleting archived log(s)
archived log file name=/disk1/oracle/work/orcva/TKRM/archivelog/2007_06_20/o1_mf_1_5_29jkdvjq_.arc RECID=91 STAMP=593611179
archived log file name=/disk1/oracle/work/orcva/TKRM/archivelog/2007_06_20/o1_mf_1_6_29jkdvbz_.arc thread=1 sequence=6
channel default: deleting archived log(s)
.
.
.
media recovery complete, elapsed time: 00:00:01
Finished recover at 20-JUN-06If you are restoring some datafiles to new locations, then execute
RESTORE TABLESPACEandRECOVER TABLESPACEin aRUNcommand. Use theSET NEWNAMEto rename datafiles, as described in "Restoring Datafiles to a Nondefault Location".The following example restores the datafiles in tablespaces
tbs_3to a new location, then performs recovery. Assume that the old datafiles were stored in the/disk1path and the new ones will be stored in the/disk2path.RUN
{
# specify the new location for each datafile
SET NEWNAME FOR DATAFILE '/disk1/oracle/dbs/tbs_31.f' TO
'/disk2/tbs_31.f';
SET NEWNAME FOR DATAFILE '/disk1/oracle/dbs/tbs_32.f' TO
'/disk2/tbs_32.f';
SET NEWNAME FOR DATAFILE '/disk1/oracle/dbs/tbs_33.f' TO
'/disk2/tbs_33.f';
RESTORE TABLESPACE tbs_3;
SWITCH DATAFILE ALL; # update control file with new filenames
RECOVER TABLESPACE tbs_3;
}
Examine the output to see if recovery was successful. If so, bring the recovered tablespace back online.
For example, enter the following command:
SQL "ALTER TABLESPACE tbs_3 ONLINE";
Performing Complete Recovery of a Datafile After Switching to a Copy
If you have image copies of the inaccessible datafiles in the flash recovery area, then you can use the SWITCH DATAFILE ... TO COPY command to point the control file at the datafile copy and then use RECOVER to recover lost changes. When the original location can be used again, you can switch datafile back to the original location. Because you do not need to restore backups, this recovery technique takes less time than traditional restore and recovery.
Note:
ASWITCH TABLESPACE ... TO COPY command is also supported for cases when all datafiles in a tablespace are lost and copies of all datafiles exist.In the basic scenario, the database is open, and some but not all of the datafiles are damaged. During the course of the day, a datafile goes missing due to storage failure. You need to 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 datafile 4.
To switch to a datafile copy and perform recovery:
Start RMAN and connect to the target database.
For example, enter the following command:
% rman
RMAN> CONNECT SYS/password@trgtRMAN displays the database status when it connects:
not started,not mounted,not open(when mounted but not open), or none (database is open).If the database is open, then take the tablespace requiring recovery offline.
For example, enter the following command to take datafile 4 offline:
SQL "ALTER DATABASE DATAFILE 4 OFFLINE";
Switch the offline datafile to the latest copy.
For example, enter the following command to point the control file to the latest image copy of datafile 4:
SWITCH DATAFILE 4 TO COPY;
Recover the datafile with the
RECOVER DATAFILEcommand.For example, enter the following command (sample output included):
RECOVER DATAFILE 4;
RMAN automatically restores archived redo logs and incremental backups. Because the database uses a flash recovery area, RMAN automatically deletes them after they have been applied.
Examine the output to see if recovery was successful. If so, bring the recovered datafile back online.
For example, enter the following command to bring datafile 4 online:
SQL "ALTER DATABASE DATAFILE 4 ONLINE";
