RMAN Interview Related Questions ?

RMAN Interview Related Questions ?

1. Difference between catalog and nocatalog?
Recovery catalog is central and can have information of many databases.

2. Difference between using recovery catalog and control file?
When new incarnation happens, the old backup information in control file will be lost. It will be preserved in recovery catalog.
In recovery catalog, we can store scripts.
Recovery catalog is central and can have information of many databases.

3. Can we use same target database as catalog?
No. The recovery catalog should not reside in the target database (database to be backed up), because the database can't be recovered in the mounted state.

4. How do u know how much RMAN task has been completed?
By querying v$rman_status or v$session_longops

5. From where list and report commands will get input?
Both the commands command quering v$ and recovery catalog (RC) views. V$BACKUP_FILES or many of the recovery catalog views such as RC_DATAFILE_COPY or RC_ARCHIVED_LOG.

6. Command to delete archive logs older than 7days?
RMAN> delete archivelog all completed before sysdate-7;

8. What is the use of crosscheck command in RMAN?
Crosscheck will be useful to check whether the catalog information is intact with OS level information.

9. What are the differences between crosscheck and validate commands?
Validate command is to examine a backup set and report whether it can be restored. RMAN scans all of the backup pieces in the specified backup sets and looks at the checksum to verify that the contents are intact so that backup can be successfully restored if necessary.

Crosscheck command is to verify the status of backups and copies recorded in the RMAN repository against media such as disk or tape. The crosscheck command only processes files created on the same device type as the channel running crosscheck.

10. Which is one is good, differential (incremental) backup or cumulative (incremental) backup?
A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

11. What is Level 0, Level 1 backup?
A level 0 incremental backup, which is the base for subsequent incremental backups, copies all blocks containing data, backing the datafile up into a backup set just as a full backup would. A level 1 incremental backup can be either of the following types:
A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

12. Can we perform level 1 backup without level 0 backup?
If no level 0 backup is available, then the behavior depends upon the compatibility mode setting. If compatibility < 10.0.0, RMAN generates a level 0 backup of the file contents at the time of the backup. If compatibility is >= 10.0.0, RMAN copies all blocks changed since the file was created, and stores the results as a level 1 backup. In other words, the SCN at the time the incremental backup is taken is the file creation SCN.

14. What is snapshot control file?
The snapshot control file is a copy of a database control file created in an operating system-specific location by RMAN. RMAN creates the snapshot control file so that it has a consistent version of a control file to use when either resynchronizing the recovery catalog or backing up the control file.

15. What is the difference between backup set and backup piece?
Backup set is logical and backup piece is physical.

16. RMAN command to backup for creating standby database?
RMAN> duplicate target database to standby database ....

17. How to do cloning by using RMAN?
RMAN> duplicate target database …

18. Suppose you lost one datafile and DB is running in ARCHIVELOG mode. You have full database backup of 1 week/day old and don’t have backup of this (newly created) datafile. How do you restore/recover file?
create the datafile and recover that datafile.
SQL> alter database create datafile ‘…path..’ size n;
RMAN> recover datafile file_id;

19. What is obsolete backup and expired backup?
A status of "expired" means that the backup piece or backup set is not found in the backup destination.
A status of "obsolete" means the backup piece is still available, but it is no longer needed. The backup piece is no longer needed since RMAN has been configured to no longer need this piece after so many days have elapsed, or so many backups have been performed.

20. What is the difference between hot backup and RMAN backup?
For hot backup, we have to put database in begin backup mode, then take backup.
RMAN won’t put database in backup mode.

21. How to put manual/user-managed backup in RMAN (recovery catalog)?
By using catalog command.
RMAN> CATALOG START WITH '/tmp/backup.ctl';

25. What is the use of nofilenamecheck in rman
When NOFILENAMECHECK is used with the DUPLICATE command, RMAN does not validate the filenames during restoration. If the primary database and the standby database are on the same host, The DUPLICATE NOFILENAMECHECK option should not be used.

26. What is RMAN ?
Recovery Manager (RMAN) is a utility that can manage your entire Oracle backup and recovery activities.
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)

27. When you take a hot backup putting Tablespace in begin backup mode, Oracle records SCN # from header of a database file.  What happens when you issue hot backup database in RMAN at block level backup? How does RMAN mark the record that the block has been backed up ?  How does RMAN know what blocks were backed up so that it doesn't have to scan them again?
In 11g, there is Oracle Block Change Tracking feature.  Once enabled; this new 10g feature records the modified since last backup and stores the log of it in a block change tracking file. During backups RMAN uses the log file to identify the specific blocks that must be backed up. This improves RMAN's performance 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 data to 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 put the tablespace in BACKUP mode, thus freezing the SCN in the header. Rather, RMAN keeps this information in either your control files or in the RMAN repository (i.e., Recovery Catalog). 

28.  What are the Architectural components of RMAN?
1.RMAN executable
2.Server processes
3.Channels
4.Target database
5.Recovery catalog database (optional)
6.Media management layer (optional)
7.Backups, backup sets, and backup pieces

29.  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

30.  Why is the catalog optional?
Because RMAN manages backup and recovery operations, it requires a place to store necessary information about the database. RMAN always stores this information in the target database control file. You can also store RMAN metadata in a recovery catalog schema contained in a separate database. The recovery catalog
schema must be stored in a database other than the target database.

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

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

33.  What is a Backup piece?
A physical binary file created by RMAN during a backup. Backup pieces are written to your backup medium, whether to disk or tape. They contain blocks from the target database's datafiles, archived redo log files, and control files. When RMAN constructs a backup piece from datafiles, there are a several 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, you must use RMAN to do it. There's no way for you to manually reconstruct database files from the backup pieces. You must use RMAN to restore files from a backup piece.

34.  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 online backups.
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.

35. RMAN Restore Preview
The PREVIEW option of the RESTORE command allows you to identify the backups required to complete a specific restore operation. The output generated by the command is in the same format as the LIST command. In addition the PREVIEW SUMMARY command can be used to produce a summary report with the same format as the LIST SUMMARY command. The following examples show how these commands are used:
# Spool output to a log file
SPOOL LOG TO c:\oracle\rmancmd\restorepreview.lst;
# Show what files will be used to restore the SYSTEM tablespace’s datafile
RESTORE 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 restore
RESTORE DATABASE PREVIEW SUMMARY;
# Close the log file
SPOOL LOG OFF;

36. Where should the catalog be created?
The recovery catalog to be used by rman should be created in a separate database other than the target database. The reason been that the target database will be shutdown while datafiles are restored.

37. How many times does oracle ask before dropping a catalog?
The default is two times one for the actual command, the other for confirmation.

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

39. Backup the database.
run
{
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;
}

40. What are the various reports available with RMAN
rman>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=0 database;
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 the files, when a command is issued through rman to backup archivelogs it uses one of the location to backup the data. When we specify delete input the location which was backedup will get deleted, if we specify delete all all log_archive_dest_n will get deleted.
DELETE all applies only to archived logs. delete expired archivelog all;

41. 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;
}

42. 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;
backup archivelog all not backed up 1 times delete input;
}

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

44. 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 command
RMAN> catalog datafilecopy '/DB01/BACKUP/users01.dbf';
restrictions:
> Accessible on disk
> A complete image copy of a single file

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

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

47. How RMAN improves backup time?
RMAN backup time consumption is very less than compared to regular online backup as RMAN copies only modified blocks

48. What is the advantage of RMAN utility?
Central Repository
Incremental Backup
Corruption Detection
Advantage over tradition backup system:
1). copies only the filled blocks i.e. even if 1000 blocks is allocated to datafile but 500 are filled with data 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.

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

50. 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 each database. 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 to match with the current incarnation. If you run the RMAN command ALTER DATABASE OPEN RESETLOGS then RMAN resets the
target database automatically so that you do not have to run RESET DATABASE. By resetting the database RMAN considers the new incarnation as the current incarnation of the database.

51. 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 backups
2. Ability to Recover one block of datafile
3. Ability to automatically backup CONTROLFILE and SPFILE
4. 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.

52. 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 to
2> '$HOME/BACKUP/RMAN/ F.bkp';
$HOME/BACKUP/RMAN/ this can be any desired location.

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

54. What is the difference between cumulative incremental and differential incremental backups?
Differential backup: This is the default type of incremental backup which backs up all blocks changed 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.

55. How do you identify the block corruption in RMAN database? How do you fix it?
using v$block_corruption view u can find which blocks corrupted.
Rman>> block recover datafile <fileid> block <blockid>;
Using the above statement u recover the corrupted blocks.
First check whether the block is corrupted or not by using this command
sql>select file# block# from v$database_block_corruption;
file# block
2 507
the above block is corrupted...
conn to Rman
To recover the block use this command...
Rman>blockrecover dataile 2 block 507;
the above command recover the block 507
Now just verify it.....
Rman>blockrecover corruption list;

56. How do you clone the database using RMAN software? Give brief steps? When do you use 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.

57. 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."

58. List some of the RMAN catalog view names which contain the catalog information?
RC_DATABASE_INCARNATION RC_BACKUP_COPY_DETAILS
RC_BACKUP_CORRUPTION
RC_BACKUP-DATAFILE_SUMMARY to name a few

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

60. How do you setup the RMAN tape backups?
RMAN Target /
run
{
Allocate channel ch1 device type sbt_tape maxpiecesize 4g
Format' 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

61. 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 a recovery_catalog_owner privilege.
3)Login into RMAN with connection string
a) export ORACLE_SID         
b) rman target catalog @connection string
4) rman> create catalog;
5) register database;

62. When do you recommend hot backup? What are the pre-reqs?
Database must be Archivelog Mode
Archive Destination must be set and LOG_ARCHIVE_START TRUE (EARLIER VERSION BEFORE 10G)
If you go through RMAN then
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE 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; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO
'/u01/app/oracle/product/10.2.0/db_2/dbs/snapcf_dba.f'; # default

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

64. 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 stripping
RAID1: Mirroring

65. 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 contingency plan. 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 managed backup.
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 a incremental backup on a weekday.
5. Schedule your backup on the time where there is least database activity this is to avoid resource huggling.
6. Backup script should always be automized via scheduled jobs. This way operators would never miss a backup period.
7. Retention period should also be considered. Try keeping atleast 2 full backups. (current and previous backup).
Cold backup: shutdown the database and copy the datafiles with the help of
O.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 backup is
1) sql> alter database begin backup;
2) copy the datafiles.
3) after copying
sql> alter database end backup;
Begin backup clause will generate the timestamp. it'll be used in backup consistency i.e. when begin backup pressed it'll generate the timestamp. During restore database will restore the data from backup till that timestamp and remaining backup will be recovered from archive log.

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

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

68. 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 and incremental backup sets, control file auto-backups, archive logs and datafile copies.

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

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

71. How can you use the CURRENT_SCN column in the V$DATABASE view to obtain the currentSCN?
A:SQL> SELECT current_scn FROM v$database;

72. 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 command
RMAN> catalogdatafilecopy '/DB01/BACKUP/users01.dbf';
restrictions:> Accessible on disk> A complete image copyof a single file

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

74. 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 datafile
3. Ability to automatically backup CONTROLFILEand SPFILE
4. Ability to delete the older ARCHIVE REDOLOG files

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

76. 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

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

78. What is the difference between cumulative incremental and differential incremental backups?
Differential backup: This is the default type of incremental backup which backs up all blocks changed 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
                   
79. 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

80. 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 in the same RUN command.

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

82. What is RMAN and how does one use it?
Recovery Manager (or RMAN) is an Oracle provided utility for backing-up, restoring and recoveringOracle Databases. RMAN ships with the database server and doesn't require a separate installation. TheRMAN executable is located in your ORACLE_HOME/bin directory.

83. What kind of backup are supported by RMAN?
Backup SetsDatafiles CopiesOS BackupWhat is the Flash Recovery Area?
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.

84. How do you define a Flash Recovery Area?
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’;

85. How do you use the V$RECOVERY_FILE_DEST view to display information regarding the flashrecovery area?
SQL> SELECT name, space_limit, space_used,space_reclaimable, number_of_filesFROM v$recovery_file_dest;

86. How can you display warning messages?
SQL> SELECT object_type, message_type,message_level, reason, suggested_actionFROM dba_outstanding_alerts;

66. How to use the best practice to use Oracle Managed File (OMF) to let Oracle database to create andmanage the underlying operating system files of a database?
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 have changed?
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.

69. How do you use the V$BACKUP_DATAFILE view to display how effective the block change trackingis in minimizing the incremental backup I/O?
SQL> SELECT file#, AVG(datafile_blocks), AVG(blocks_read),AVG (blocks_read/datafile_blocks), AVG(blocks)FROM v$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 to decrease the timebetween the incremental backups.

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

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

72. How do you backup datafiles and control files?
RMAN> BACKUP DATAFILE 3;
RMAN> BACKUP CURRENT CONTROLFILE;

73. Use a fast recovery without restoring all backups from their backup location to the location specified into the controlfile.
RMAN> SWITCH DATABASE TO COPY;

74. What are RTO, MTBF, and MTTR?
RTO: Recovery Time objective-is the maximum amount of time that the database can be unavailable  and still stasfy SLA's
MTBF (Meant tiem Between Failure)-
MTTR (Mean tie to recover)-  fast recovery solutions

75. 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 encryption
RMAN> CONFIGURE ENCRYPTION FOR DATABASE ON; -- encrypt backups

76. 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-forward until a specific point-in-time (before the disaster occurred), or roll-forward until the last transaction recorded in the log files.
SQL> connect SYS as SYSDBA
SQL> 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;
}

77. 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

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