RMAN Frequently Asked Questions

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RMAN Frequently Asked Questions1. What is RMAN ?Recovery Manager (RMAN) is a utility that can manage your entire Oracle backup and recoveryactivities.Which Files must be backed up?Database Files (with RMAN)Control Files (with RMAN)

Offline Redolog Files (with RMAN)INIT.ORA (manually)Password Files (manually)2. When you take a hot backup putting Tablespace in begin backup mode, Oracle recordsSCN # from header of a database file. What happens when you issue hot backup databasein RMAN at block level backup? How does RMAN mark the record that the block has beenbacked up ? How does RMAN know what blocks were backed up so that it doesn't have toscan them again?In 11g, there is Oracle Block Change Tracking feature. Once enabled; this new 10g feature recordsthe modified since last backup and stores the log of it in a block change tracking file. During backupsRMAN uses the log file to identify the specific blocks that must be backed up. This improves RMAN'sperformance as it does not have to scan whole datafiles to detect changed blocks.Logging of changed blocks is performed by the CTRW process which is also responsible for writing datato the block change tracking file. RMAN uses SCNs on the block level and the archived redo logs to

resolve any inconsistencies in the datafiles from a hot backup. What RMAN does not require is to putthe tablespace in BACKUP mode, thus freezing the SCN in the header. Rather, RMAN keeps thisinformation in either your control files or in the RMAN repository (i.e., Recovery Catalog).3. What are the Architectural components of RMAN?1.RMAN executable2.Server processes3.Channels

4.Target database5.Recovery catalog database (optional)6.Media management layer (optional)7.Backups, backup sets, and backup pieces4. What are Channels?A channel is an RMAN server process started when there is a need to communicate with an I/O device,such as a disk or a tape. A channel is what reads and writes RMAN backup files. It is through the

allocation of channels that you govern I/O characteristics such as:Type of I/O device being read or written to, either a disk or an sbt_tape

Number of processes simultaneously accessing an I/O device

Maximum size of files created on I/O devices

Maximum rate at which database files are read

Maximum number of files open at a time

5. Why is the catalog optional?Because RMAN manages backup and recovery operations, it requires a place to store necessaryinformation about the database. RMAN always stores this information in the target database controlfile. You can also store RMAN metadata in a recovery catalog schema contained in a separatedatabase. The recovery catalog

schema must be stored in a database other than the target database.

6. What does complete RMAN backup consist of ?A backup of all or part of your database. This results from issuing an RMAN backup command. Abackup consists of one or more backup sets.

7. What is a Backup set?A logical grouping of backup files -- the backup pieces -- that are created when you issue an RMANbackup command. A backup set is RMAN's name for a collection of files associated with a backup. Abackup set is composed of one or more backup pieces.

8. What is a Backup piece?


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A physical binary file created by RMAN during a backup. Backup pieces are written to your backupmedium, whether to disk or tape. They contain blocks from the target database's datafiles, archivedredo log files, and control files. When RMAN constructs a backup piece from datafiles, there are aseveral rules that it follows:A datafile cannot span backup sets

A datafile can span backup pieces as long as it stays within one backup set

Datafiles and control files can coexist in the same backup sets

Archived redo log files are never in the same backup set as datafiles or control files RMAN is the

only tool that can operate on backup pieces. If you need to restore a file from an RMAN backup, youmust use RMAN to do it. There's no way for you to manually reconstruct database files from thebackup pieces. You must use RMAN to restore files from a backup piece.9. What are the benefits of using RMAN?1. Incremental backups that only copy data blocks that have changed since the last backup.2. Tablespaces are not put in backup mode, thus there is noextra redo log generation during onlinebackups.3. Detection of corrupt blocks during backups.4. Parallelization of I/O operations.5. Automatic logging of all backup and recovery operations.6. Built-in reporting and listing commands.10. RMAN Restore PreviewThe PREVIEW option of the RESTORE command allows you to identify the backups required tocomplete a specific restore operation. The output generated by the command is in the same format asthe LIST command. In addition the PREVIEW SUMMARY command can be used to produce a summaryreport with the same format as the LIST SUMMARY command. The following examples show how thesecommands are used:# Spool output to a log fileSPOOL LOG TO c:\oracle\rmancmd\restorepreview.lst;# Show what files will be used to restore the SYSTEM tablespaces datafileRESTORE DATAFILE 2 PREVIEW;# Show what files will be used to restore a specific tablespace

RESTORE TABLESPACE users PREVIEW;# Show a summary for a full database restoreRESTORE DATABASE PREVIEW SUMMARY;# Close the log fileSPOOL LOG OFF;11. Where should the catalog be created?The recovery catalog to be used by rman should be created in a separate database other than thetarget database. The reason been that the target database will be shutdown while datafiles arerestored.12. How many times does oracle ask before dropping a catalog?The default is two times one for the actual command, the other for confirmation.13. How to view the current defaults for the database.RMAN> show all;RMAN configuration parameters are:CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 3 DAYS;CONFIGURE BACKUP OPTIMIZATION OFF; # defaultCONFIGURE DEFAULT DEVICE TYPE TO DISK; # defaultCONFIGURE CONTROLFILE AUTOBACKUP OFF; # default

CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO %F; # defaultCONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # defaultCONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # defaultCONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # defaultCONFIGURE MAXSETSIZE TO UNLIMITED; # defaultCONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # defaultCONFIGURE SNAPSHOT CONTROLFILE NAME TO/u02/app/oracle/product/10.1.0/db_1/dbs/snapcf_test.f; # default

14. Backup the database.run
http://www.bestremotedba.com/rman-restore-preview/http://www.bestremotedba.com/rman-restore-preview/


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{backup incremental level $level ${level_keyword}tag INC${target_db}_$level database include current controlfile;backup archivelog all not backed up 1 times delete input;}15. How to resolve the ora-19804 errorBasically this error is because of flash recovery area been full. One way to solve is to increase the

space available for flashback database.sql>ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE=5G; It can be set to K,M or G.rman>backup database;.channel ORA_DISK_1: specifying datafile(s) in backupsetincluding current controlfile in backupsetincluding current SPFILE in backupsetchannel ORA_DISK_1: starting piece 1 at 04-JUL-05channel ORA_DISK_1: finished piece 1 at 04-JUL-05piecehandle=/u02/app/oracle/flash_recovery_area/TEST/backupset/2005_07_04/o1_mf_ncsnf_TAG20050704T205840_1dmy15cr_.bkp comment=NONEchannel ORA_DISK_1: backup set complete, elapsed time: 00:00:03Finished backup at 04-JUL-05

Oracle FlashbackAfter taking a back up resync the database.Restoring the whole database.run {shutdown immediate;startup mount;restore database;

recover database;alter database open;}16. What are the various reports available with RMANrman>list backup;rman> list archive;

17. What does backup incremental level=0 database do?

Backup database level=0 is a full backup of the database. rman>>backup incremental level=0database;You can also use backup full database; which means the same thing as level=0;18. What is the difference between DELETE INPUT and DELETE ALL command in backup?Generally speaking LOG_ARCHIVE_DEST_n points to two disk drive locations where we archive thefiles, when a command is issued through rman to backup archivelogs it uses one of the location tobackup the data. When we specify delete input the location which was backedup will get deleted, if wespecify delete all all log_archive_dest_n will get deleted.DELETE all applies only to archived logs. delete expired archivelog all;19. How do I backup archive log?In order to backup archivelog we have to do the following:-run{allocate channel t1 type 'SBT_TAPE';

delete noprompt archivelog until time = 'sysdate-3/24';delete noprompt obsolete;release channel t1;}

20. How do I do a incremental backup after a base backup?run{backup incremental level $level ${level_keyword}tag INC${target_db}_$level database include current controlfile;


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backup archivelog all not backed up 1 times delete input;}

21. In catalog database, if some of the blocks are corrupted due to system crash, How willyou recover?using RMAN BLOCK RECOVER command

22. You have taken a manual backup of a datafile using o/s. How RMAN will know about it?You have to catalog that manual backup in RMAN's repository by commandRMAN> catalog datafilecopy '/DB01/BACKUP/users01.dbf';restrictions:> Accessible on disk> A complete image copy of a single file

23. Where RMAN keeps information of backups if you are using RMAN without Catalog?RMAN keeps information of backups in the control file.CATALOG vs NOCATALOGthe difference is only who maintains the backup records like when is the last successful backupincremental differential etc.In CATALOG mode another database (TARGET database) stores all the information.In NOCATALOG mode controlfile of Target database is responsible.

24. How do you see information about backups in RMAN?RMAN> List Backup;Use this SQL to checkSQL> SELECT sid totalwork sofar FROM v$session_longops WHERE sid 153;Here give SID when back start it will show SID

25. How RMAN improves backup time?RMAN backup time consumption is very less than compared to regular online backup as RMAN copiesonly modified blocks

26. What is the advantage of RMAN utility?Central RepositoryIncremental Backup

Corruption DetectionAdvantage over tradition backup system:1). copies only the filled blocks i.e. even if 1000 blocks is allocated to datafile but 500 are filled withdata then RMAN will only create a backup for that 500 filled blocks.2). incremental and accumulative backup.3). catalog and no catalog option.4). detection of corrupted blocks during backup;5). can create and store the backup and recover scripts.6). increase performance through automatic parallelization( allocating channels) less redo generation.

27. List the encryption options available with RMAN?RMAN offers three encryption modes: transparent mode, password mode and dual mode.

28. What are the steps required to perform in $ORACLE_HOME for enabling the RMAN

backups with netbackup or TSM tape library software?I can explain what are all the steps to take a rman backup with TSM tape library as follows1.Install TDPO (default path /usr/tivoli/tsm/client/oracle/)2.Once u installed the TDPO automatically one link is created from TDPO directory to /usr/lib.Now weneed to Create soft link between OS to ORACLE_HOMEln -s /usr/lib/libiobk64.a $ORACLE_HOME/lib/libobk.a(very imporatant)3.Uncomment and Modify tdpo.opt file which in/usr/tivoli/tsm/client/oracle/bin/tdpo.opt as followsDSMI_ORC_CONFIG /usr/Tivoli/tsm/client/oracle/bin64/dsm.optDSMI_LOG /home/tmp/oracle


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TDPO_NODE backupTDPO_PSWDPATH /usr/tivoli/tsm/client/oracle/bin644.create dsm.sys file in same path and add the entriesSErvername TCPPort 1500passwordacess promptnodename backup

enablelanfree yesTCPSERVERADDRESS 5.Create dsm.opt file add an entrySErvername 6.Then take backupRMAN>run{allocate channel t1 type 'sbt_tape' parms'ENV (TDPO_OPTFILE /usr/tivoli/tsm/client/oracle/bin64/tdpo.opt)';backup database include current controlfile;release channel t1;}

29. What is the significance of incarnation and DBID in the RMAN backups?

When you have multiple databases you have to set your DBID (Database Id) which is unique to eachdatabase. You have to set this before you do any restore operation from RMAN.There is possibility that incarnation may be different of your database. So it is advised to reset tomatch with the current incarnation. If you run the RMAN command ALTER DATABASE OPENRESETLOGS then RMAN resets thetarget database automatically so that you do not have to run RESET DATABASE. By resetting thedatabase RMAN considers the new incarnation as the current incarnation of the database.

30. List at least 6 advantages of RMAN backups compare to traditional hot backups?RMAN has the following advantages over Traditional backups:1. Ability to perform INCREMENTAL backups2. Ability to Recover one block of datafile3. Ability to automatically backup CONTROLFILE and SPFILE4. Ability to delete the older ARCHIVE REDOLOG files, with the new one's automatically.

5. Ability to perform backup and restore with parallelism.6. Ability to report the files needed for the backup.7. Ability to RESTART the failed backup, without starting from beginning.8. Much faster when compared to other TRADITIONAL backup strategies.

31. How do you enable the autobackup for the controlfile using RMAN?issue command at rman prompt.....RMAN> configure controlfile autobackup on;also we can configure controlfile backup format......RMAN> configure controlfile autobackup format for device type disk to2> '$HOME/BACKUP/RMAN/ F.bkp';$HOME/BACKUP/RMAN/ this can be any desired location.

32. How do you identify what are the all the target databases that are being backed-up with

RMAN database?You dont have any view to identify whether it is backed up or not . The only option is connect to thetarget database and give list backup this will give you the backup information with date and timing.

33. What is the difference between cumulative incremental and differential incrementalbackups?Differential backup: This is the default type of incremental backup which backs up all blockschanged after the most recent backup at level n or lower.Cumulative backup: Backup all blocks changed after the most recent backup at level n-1 or lower.


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34. How do you identify the block corruption in RMAN database? How do you fix it?using v$block_corruption view u can find which blocks corrupted.Rman>> block recover datafile block ;Using the above statement u recover the corrupted blocks.First check whether the block is corrupted or not by using this commandsql>select file# block# from v$database_block_corruption;file# block

2 507the above block is corrupted...conn to RmanTo recover the block use this command...Rman>blockrecover dataile 2 block 507;the above command recover the block 507Now just verify it.....Rman>blockrecover corruption list;

35. How do you clone the database using RMAN software? Give brief steps? When do youuse crosscheck command?Check whether backup pieces proxy copies or disk copies still exist.Two commands available in RMAN to clone database:1) Duplicate

2) Restore.

36. What is the difference between obsolete RMAN backups and expired RMAN backups?The term obsolete does not mean the same as expired. In short obsolete means "not needed "whereas expired means "not found."

37. List some of the RMAN catalog view names which contain the catalog information?

RC_DATABASE_INCARNATION RC_BACKUP_COPY_DETAILSRC_BACKUP_CORRUPTIONRC_BACKUP-DATAFILE_SUMMARY to name a few

38. What is db_recovery_file_dest ? When do you need to set this value?If Database Flashback option is on then use this option.

39. How do you setup the RMAN tape backups?RMAN Target /run{Allocate channel ch1 device type sbt_tape maxpiecesize 4gFormat' D_ U_ T_ t';sql 'alter system switch logfile';Backup database;backup archivelog from time 'sysdate-7';Backup Format ' D_CTLFILE_P_ U_ T_ t' Current controlfile;release channel ch1;}This is backup script for Tivoli Backup Server

40. How do you install the RMAN recovery catalog?Steps to be followed:1) Create connection string at catalog database.2) At catalog database create one new user or use existing user and give that user arecovery_catalog_owner privilege.3)Login into RMAN with connection stringa) export ORACLE_SIDb) rman target catalog @connection string4) rman> create catalog;5) register database;


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41. When do you recommend hot backup? What are the pre-reqs?Database must be Archivelog ModeArchive Destination must be set and LOG_ARCHIVE_START TRUE (EARLIER VERSION BEFORE 10G)If you go through RMAN thenCONFIGURE RETENTION POLICY TO REDUNDANCY 1; # defaultCONFIGURE BACKUP OPTIMIZATION OFF; # default

CONFIGURE DEFAULT DEVICE TYPE TO DISK; # defaultCONFIGURE CONTROLFILE AUTOBACKUP ON;CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO'/u01/oracle/autobackup/ F';CONFIGURE DEVICE TYPE DISK PARALLELISM 2BACKUP TYPE TO BACKUPSET; # defaultCONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # defaultCONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # defaultCONFIGURE MAXSETSIZE TO UNLIMITED; # defaultCONFIGURE ENCRYPTION FOR DATABASE OFF; # defaultCONFIGURE ENCRYPTION ALGORITHM 'AES128'; # defaultCONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # defaultCONFIGURE SNAPSHOT CONTROLFILE NAME TO'/u01/app/oracle/product/10.2.0/db_2/dbs/snapcf_dba.f'; # default

42. What is the difference between physical and logical backups?In Oracle Logical Backup is "which is taken using either Traditional Export/Import or Latest DataPump". Where as Physical backup is known "when you take Physical O/s Database related Files asBackup".

43. What is RAID? What is RAID0? What is RAID1? What is RAID 10?RAID: It is a redundant array of independent disk

RAID0: Concatenation and strippingRAID1: Mirroring

44. What are things which play major role in designing the backup strategy?I Believe in designing a good backup strategy it will not only be simply backup but also a contingencyplan. In this case you should consider the following:1. How long is the allowable down time during recovery? - If short you could consider using

dataguard.2. How long is the backup period? - If short I would advise to use RMAN instead of user managedbackup.3. If limited disk space for backup never use user managed backup.4. If the database is large you could consider doing full rman backups on a weekend and do aincremental backup on a weekday.5. Schedule your backup on the time where there is least database activity this is to avoid resourcehuggling.6. Backup script should always be automized via scheduled jobs. This way operators would never missa backup period.7. Retention period should also be considered. Try keeping atleast 2 full backups. (current andprevious backup).Cold backup: shutdown the database and copy the datafiles with the help ofO.S. command. this is simply copying of datafiles just like any other text file copy.

Hot backup: backup process starts even though database in running. The process to take a hot backupis1) sql> alter database begin backup;2) copy the datafiles.3) after copyingsql> alter database end backup;Begin backup clause will generate the timestamp. it'll be used in backup consistency i.e. when beginbackup pressed it'll generate the timestamp. During restore database will restore the data frombackup till that timestamp and remaining backup will be recovered from archive log.


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45. What is hot backup and what is cold backup?Hot backup when the database is online cold backup is taken during shut down period

46. How do you test that your recovery was successful?SQL> SELECT count(*) FROM flashback_table;

47. How do you backup the Flash Recovery Area?

A:RMAN> BACKUP RECOVERY FILES;The files on disk that have not previously been backed up will be backed up.They are full andincremental backup sets, control file auto-backups, archive logs and datafile copies.

48. How to enable Fast Incremental Backup to backup only those data blocks that havechanged?A:SQL> ALTER DATABASE enable BLOCK CHANGE TRACKING;

49. How do you set the flash recovery area?A:SQL> ALTER SYSTEM SET db_recovery_file_dest_size = 100G;SQL> ALTER SYSTEM SETdb_recovery_file_dest =/u10/oradata/school;

50. How can you use the CURRENT_SCN column in the V$DATABASE view to obtain thecurrentSCN?

A:SQL> SELECT current_scn FROM v$database;

51. You have taken a manual backup of a datafile using o/s. How RMAN will know about it?You have to catalog that manual backup in RMAN's repository by commandRMAN> catalogdatafilecopy '/DB01/BACKUP/users01.dbf';restrictions:> Accessible on disk> A complete image copyof a single file

52. In catalog database, if some of the blocks are corrupted due to system crash, How willyou recover?using RMAN BLOCK RECOVER command

53. List advantages of RMAN backups compare to traditional hot backups?RMAN has the following advantages over Traditional backups:1. Ability to perform INCREMENTALbackups

2. Ability to Recover one block of datafile3. Ability to automatically backup CONTROLFILEand SPFILE4. Ability to delete the older ARCHIVE REDOLOG files

54. How do you identify the expired, active, obsolete backups? Which RMAN command youuse?Use command:Rman > crosscheck backup;Rman > crosscheck archivelog all;Rman > listbackup;Rman > list archive logall

55. How do you enable the autobackup for the controlfile using RMAN?RMAN> configure controlfile autobackup on;

also we can configurecontrolfile backup format......RMAN> configure control file auto backup format for device type disk

56. How do you identify what are the all the target databases that are being backed-up withRMAN database?You dont have any view to identify whether it is backed up or not . The only option is connect to thetarget database and give list backup, this will give you the backup information with date and timing

57. What is the difference between cumulative incremental and differential incrementalbackups?


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Differential backup: This is the default type of incremental backup which backs up all blocks changedafter the most recent backup at level n or lower.Cumulative backup: Backup all blocks changed after the most recent backup at level n-1 or lower58. Explain how to setup the physical stand by database with RMAN?$ Export ORACLE_SID=TEST $ rman target /RMAN> show all;

Using target database controlfile instead of recovery catalog RMAN configuration parameters are:CONFIGURE RETENTIONPOLICY TO RECOVERY WINDOW OF 1 DAYS;CONFIGURE BACKUP OPTIMIZATION

59. What is auxiliary channel in RMAN? When do you need this?An auxiliary channel is a link to auxiliary instance. If you do not have automatic channels configured,then before issuing the DUPLICATE command, manually allocate at least one auxiliary channel with inthe same RUN command.

60. What is backup set?RMAN can also store its backups in an RMAN-exclusive format which is called backup set. A backupsetis a collection of backup pieces, each of which may contain one or more datafile backups

61. What is RMAN and how does one use it?

Recovery Manager (or RMAN) is an Oracle provided utility for backing-up, restoring andrecoveringOracle Databases. RMAN ships with the database server and doesn't require a separateinstallation. TheRMAN executable is located in your ORACLE_HOME/bin directory.

62. What kind of backup are supported by RMAN?Backup SetsDatafiles CopiesOS BackupWhat is the Flash Recovery Area?A: It is a unified storage location for all recovery-related files and activities in an Oracle Database.

Itincludes Control File, Archived Log Files, Flashback Logs, Control File Autobackups, Data Files,andRMAN files.

63. How do you define a Flash Recovery Area?A: To define a Flash Recovery Area set the following Oracle Initialization Parameters.SQL> ALTER SYSTEM SET db_recovery_file_dest_size = 100G;SQL> ALTER SYSTEM SET db_recovery_file_dest = /u10/oradata/school;

64. How do you use the V$RECOVERY_FILE_DEST view to display information regarding theflashrecovery area?A:SQL> SELECT name, space_limit, space_used,space_reclaimable, number_of_filesFROMv$recovery_file_dest;

65. How can you display warning messages?A:SQL> SELECT object_type, message_type,message_level, reason, suggested_actionFROMdba_outstanding_alerts;

66. How to use the best practice to use Oracle Managed File (OMF) to let Oracle database tocreate andmanage the underlying operating system files of a database?A:SQL> ALTER SYSTEM SETdb_create_file_dest = /u03/oradata/school;SQL> ALTER SYSTEM SETdb_create_online_dest_1 = /u04/oradata/school;

67. How to enable Fast Incremental Backup to backup only those data blocks that havechanged?A:SQL> ALTER DATABASE enable BLOCK CHANGE TRACKING;

68. How do you monitor block change tracking?A:SQL> SELECT filename, status, bytes FROM v$block_change_tracking;It shows where the block change-tracking file is located, the status of it and the size.


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69. How do you use the V$BACKUP_DATAFILE view to display how effective the blockchange trackingis in minimizing the incremental backup I/O?A:SQL> SELECT file#, AVG(datafile_blocks), AVG(blocks_read),AVG (blocks_read/datafile_blocks),AVG(blocks)FROM v$backup_datafileWHERE used_change_tracking = YES AND incremental_level >0GROUP BY file#;If the AVG (blocks_read/datafile_blocks) column is high then you may have todecrease the timebetween the incremental backups.

70. How do you backup the entire database?A:RMAN> BACKUP DATABASE;

71. How do you backup an individual tablespaces?A:RMAN> CONFIGURE DEFAULT DEVICE TYPE TO DISK;RMAN> BACKUP TABLESPACE system;

72. How do you backup datafiles and control files?A:RMAN> BACKUP DATAFILE 3;RMAN> BACKUP CURRENT CONTROLFILE;Use a fast recovery without restoring all backups from their backup location to the location specifiedinthe controlfile.A:RMAN> SWITCH DATABASE TO COPY;

73. RMAN will adjust the control file so that the data files point to the backup file locationand then starts recovery.Why use Rman ?A. 1. No Extra Costs.. It is available free.2.RMAN introduced in Oracle 8 it has become simpler with new version and easier that user managedbackups.3.Proper Security4.You are 100% sure your database has been backed up .

5.It contains details of backup taken in the central repository6.Facility of Testing validity of backups also command like cross check to checkthe status of backup.7.Oracle 10g has got further optimized incremental backups with has resulted inimprovement ofperformance during backup8.and recovery time9.Parrallel operation are supported10.Better Querying facility for knowing different details of backup.

11.No Extra redo generated when backup is taken. compared to online backup12.Without rman.which results in saving of space in hard disk.13.RMAN is an intelligent tool14.Maintains repository of backup metadata.15.Remembers backup locations16.Knows what needs backup set locations17.Knows what needs to be backed up18.Knows what is required for recovery19.Know what backups are redundant20.It handles database corruptions

74. Oracle Enhancement for Rman in 10gA. 1.Flash Recovery Area2.Incrementally Updated Backups

3.Faster Incremental Backups4.SWITCH DATABASE COMMAND.5.Binary Compression6.Global Scripting7.Duration Clause8.Configure This9.Oracle Enhancement for Rman in 10g10.Automatic Channel Failover11.Compress Backup Sets12.Recovery Through Reset Logs


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13.Cross Backup Sets

75. Global ScriptingA.RMAN> print script full_backup to file 'my_script_file.txt'Oracle Database 10g provides a new concept of global scripts, which you can executeagainst anydatabase registered in the recovery catalog, as long as your RMAN client isconnected to the recoverycatalog and a target database simultaneously.CPISOLUTION.COM

RMAN> create global script global_full_backup

76. Outline the steps for recovery of missing data file?Losing Datafiles Whenever you are in NoArchivelog Mode:###################################################If you are in noarchivelog mode and you loss any datafile then whether it is temporary or permanentmedia failure, the database will automatically shut down. If failure is temporary then correct theunderline hardware and start the database. Usually crash recovery will perform recovery of thecommitted transaction of the database from online redo log files. If you have permanent media failurethen restore a whole database from a good backup. How to restore a database is as follows:

If a media failure damages datafiles in a NOARCHIVELOG database, then the only option for recoveryis usually to restore a consistent whole database backup. As you are in noarchivelog mode so you

have to understand that changes after taken backup is lost.

If you logical backup that is export file you can import that also.

In order to recover database in noarchivelog mode you have to follow the following procedure.

1)If the database is open shutdown it.

SQL>SHUTDOWN IMMEDIATE;

2)If possible, correct the media problem so that the backup database files can be restored to theiroriginal locations.

3)Copy all of the backup control files, datafiles to the default location if you corrected media failure.However you can restore to another location. Remember that all of the files not only the damaged

files.

4)Because online redo logs are not backed up, you cannot restore them with the datafiles and controlfiles. In order to allow the database to reset the online redo logs, you must have to do incompleterecovery:

RECOVER DATABASE UNTIL CANCELCANCEL

5)Open the database in RESETLOGS mode:ALTER DATABASE OPEN RESETLOGS;

In order to rename your control files or in case of media damage you can copy it to another locationand then by setting (if spfile)

STARTUP NOMOUNTalter system setcontrol_files='+ORQ/orq1/controlfile/control01.ctl','+ORQ/orq1/controlfile/control02.ctl'scope=spfile;STARTUP FORCE MOUNT;

In order to rename data files or online redo log files first copy it to new location and then point controlfile to new location by,ALTER DATABASE RENAME FILE '+ORQ/orq1/datafile/system01.dbf';'TO '+ORQ/orq1/datafile/system02.dbf';


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Losing Datafiles Whenever you are in Archivelog Mode:###################################################If the datafile that is lost is under SYSTEM tablespace or if it is a datafile contain active undo segmentsthen database shuts down. If the failure is temporary then correct the underline hardware and startthe database. Usually crash recovery will perform recovery of the committed transaction of thedatabase from online redo log files.

If the datafile that is lost in not under SYSTEM tablespace and not contain active undo segments thenthe affected datafile is gone to offline. The database remains open. In order to fix the problem takethe affected tablespace offline and then recover the tablespace.

77. Outline the steps for recovery with missing online redo logs?Redo log is CURRENT (DB was shut down cleanly)If the CURRENT redo log is lost and if the DB is closed consistently, OPEN RESETLOGS can be issueddirectly without any transaction loss. It is advisable to take a full backup of DB immediately afterthe STARTUP.Redo log is CURRENT (DB was not shut down cleanly)When a current redo log is lost, the transactions in the log file are also lost before making to archivedlogs. Since a DB startup can no more perform a crash recovery (since all the now-available online logfiles are not sufficient to startup the DB in consistent state), an incomplete media recovery is the only

option. We will need to restore the DB from a previous backup and restore to the point just before thelost redo log file. The DB will need to be opened inRESETLOGS mode. There is some transaction loss inthis scenario.RMAN> RESTORE CONTROLFILE FROM '';RMAN> ALTER DATABASE MOUNT;RMAN> RESTORE DATABASE;RMAN> RECOVER DATABASE UNTIL TIME "to_date('MAR 05 2009 19:00:00','MON DD YYYY

HH24:MI:SS')";RMAN> ALTER DATABASE OPEN RESETLOGS;

78. Outline steps for recovery with missing archived redo logs?If a redo log file is already archived, its loss can safely be ignored. Since all the changes in the DB arenow archived and the online log file is only waiting for its turn to be re-written by LGWR (redo log filesare written circularly) the loss of the redo log file doesnt matter much. It may be re-created using the

commandSQL> STARTUP MOUNT;SQL> ALTER DATABASE CLEAR LOGFILE GROUP ;This will re-create all groups and no transactions are lost. The database can be opened normally afterthis.

79. What is FRA ? When do you use this ?Flash recovery area where you can store not only the traditional components found in a backupstrategy such as control files, archived log files, and Recovery Manager (RMAN) datafile copies butalso a number of other filecomponents such as flashback logs. The flash recovery area simplifies backup operations, and itincreases the availability of the database because many backup and recovery operations using theflash recovery area can be performed when the database is open and available to users.

Because the space in the flash recovery area is limited by the initialization parameter DB_RECOVERY_FILE_DEST_SIZE , the Oracle database keeps track of which files are no longer needed ondisk so that they can be deleted when there is not enough free space for new files. Each time a file isdeleted from the flash recovery area, a message is written to the alert log.

A message is written to the alert log in other circumstances. If no files can be deleted, and therecovery area used space is at 85 percent, a warning message is issued. When the space used is at 97percent, a critical warning isissued. These warnings are recorded in the alert log file, are viewable in the data dictionary viewDBA_OUTSTANDING_ALERTS , and are available to you on the main page of the EM Database Control


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80. What is Channel? How do you enable the parallel backups with RMAN?Channel is a link that RMAN requires to link to target database. This link is required when backup andrecovery operations are performed and recorded. This channel can be allocated manually or can bepreconfigured by usingautomatic channel allocation.

The number of allocated channels determines the maximum degree of parallelism that is used duringbackup, restore or recovery. For example, if you allocate 4 channels for a backup operation, 4background processes for the operation can run concurrently.

Parallelization of backup sets allocates multiple channels and assigns files to specific channels. You canconfigure parallel backups by setting a PARALLELISM option of the CONFIGURE command to a valuegreater than 1 or bymanually allocating multiple channels.

RMAN> CONFIGURE DEVICE TYPE PARALLELISM 2 BACKUP TYPE TO COMPRESSED BACKUPSET;

81. What are RTO, MTBF, and MTTR?RTO: Recovery Time objective-is the maximum amount of time that the database can be unavailableand still stasfy SLA's

MTBF (Meant tiem Between Failure)-MTTR (Mean tie to recover)- fast recovery solutions

82. How do you enable the encryption for RMAN backups?If you wish to modify your existing backup environment so that all RMAN backups are encrypted,perform the following steps: Set up the Oracle Encryption Wallet

Issue the following RMAN command:

RMAN> CONFIGURE ENCRYPTION ALGORITHM 'AES256'; -- use 256 bit encryptionRMAN> CONFIGURE ENCRYPTION FOR DATABASE ON; -- encrypt backups

83. What is the difference between restoring and recovering?Restoring involves copying backup files from secondary storage (backup media) to disk. This can be

done to replace damaged files or to copy/move a database to a new location.Recovery is the process of applying redo logs to the database to roll it forward. One can roll-forwarduntil a specific point-in-time (before the disaster occurred), or roll-forward until the last transactionrecorded in the log files.SQL> connect SYS as SYSDBASQL> RECOVER DATABASE UNTIL TIME '2001-03-06:16:00:00' USING BACKUP CONTROLFILE;RMAN> run {set until time to_date('04-Aug-2004 00:00:00', 'DD-MON-YYYY HH24:MI:SS');restore database;recover database;

}

What are the various tape backup solutions available in the market?How do you generate the begin backup script?

Outline the steps for recovering the full database from cold backup?Explain the steps to perform the point in time recovery with a backup which is taken beforethe resetlogs of the db?Outline the steps involved in TIME based recovery from the full database from hot backup?Is it possible to take Catalog Database Backup using RMAN? If Yes, How?Can a schema be restored in oracle 9i RMAN when the schema having numerous tablespaces?Outline the steps for changing the DBID in a cloned environment?How do you identify the expired, active, obsolete backups? Which RMAN command you use?Explain how to setup the physical stand by database with RMAN?


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List the steps required to enable the RMAN backup for a target database?How do you verify the integrity of the image copy in RMAN environment?Outline the steps involved in SCN based recovery from the full database from hot backup?Outline the steps involved in CANCEL based recovery from the full database from hotbackup?Outline the steps involved in TIME based recovery from the full database from hot backup?Is it possible to specific tables when using RMAN DUPLICATE feature? If yes, how?

Explain the steps to perform the point in time recovery with a backup which is taken beforethe resetlogs of the db?Outline the steps for recovering the full database from cold backup?How do you generate the begin backup script?

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