Oracle RMAN Interview Questions And Answers

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

Yes, you can perform backup of catalog database using RMAN with below steps:
1. Start the RMAN with NOCATALOG option.
2. Run the recovery catalog database in ARCHIVELOG mode.
3. set the retention policy to a REDUNDANCY value greater than 1.
4. Backup the database onto two separate media(disk and tape), You can use BACKUP COPIES 2.
5. Donot use another recovery catalog as the repository for these backups.
6. configure the controlfile autoback feature to ON.

Two commands available in RMAN to clone database: 1) Duplicate 2) Restore.

To take a rman backup with TSM tape library as follows
1.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 we need to Create soft link between OS to ORACLE_HOME ln -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/oracleTDPO_NODE backupTDPO_PSWDPATH /usr/tivoli/tsm/client/oracle/bin64
4.create dsm.sys file in same path and add the entriesSErvername TCPPort 1500 passwordacess prompt nodename backup enablelanfree yesTCPSERVERADDRESS
5.Create dsm.opt file add an entrySErvername 5. 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; }

Using RMAN BLOCK RECOVER command

RC_DATABASE_INCARNATION,
RC_BACKUP_COPY_DETAILS,
RC_BACKUP_CORRUPTION,
RC_BACKUP-DATAFILE_SUMMARY to name a few

Please share your answers.

RMAN offers three encryption modes:
transparent mode,
password mode,
and dual mode

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.
Holt 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.

RAID: It is a redundant array of independent disk
RAID0: Concatenation and stripping
RAID1: Mirroring

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;Thks..

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

The steps are:
1) Shutdown the database
2) Restore data files
3) Mount the database
4) Recover the database
(sql> recover database until time 2005-12-14:12:10:03 Time base)
(sql> recover database until change scn base)
5) Open the database with the resetlogs option
(sql>atler database open resetlogs)

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".

It is possible to use RMAN duplicate features to specific tables,with RMAN Duplicate we first create a target or duplicate single instance database and then convert the single instance database to a RAC database.

Note: Mount the databse $export ORACLE_SID=test$ nid target=system/managerIt will change and automaticaly generate new id and asign it to the database.

Oracle database help us to reduce time for taking backup using followings

1) Oracle performs BLOCKlevel backup.
2) DBA can allocate channels which will start the backup activity in PARALLEL, but we need to ensure that not too many channels have been allocated. Number of allocated channel should not be more than number of CPU.

Obsolete: means the backup piece is still available,but it is no longer needed.It depends on retention policy,i,e.recovery window .

Expired: means the backup piece or backup set is not found in the backup destination.

Create pfile from spfile
Edit pfile with _allow_resetlog_currpuation=true

1) Connect / as sysdba
2) Startup
3) Recover database until cancel;
4) Alter database open resetlogs;

In RMAN restore:

RMAN> RESTORE CONTROLFILE FROM '[[Location]]';
RMAN> ALTER DATABASE MOUNT;
RMAN> RESTORE DATABASE;
RMAN> RECOVER DATABASE UNTIL TIME "[[Time]]";
RMAN> ALTER DATABASE OPEN RESETLOGS;

You can use incremental backup either differential or accumalative. so you dont have to backup the whole database everytime just the changes made

The encryption of backup sets by using one of the algorithms listed in V$RMAN_ENCRYPTION_ALGORITHMS. RMAN can transparently encrypt data written to backup sets and decrypt those backup sets when they are needed in a RESTORE operation. RMAN offers three modes of encryption: transparent, password-protected, and dual-mode.

DBID means database id.Incunation means: Database incarnation is effectively a new “version” of the database that happens when you reset the online redo logs using “alter database open resetlogs;”.Database incarnation falls into following category Current, Parent, Ancestor and Siblingi) Current Incarnation: The database incarnation in which the database is currently generating redo.ii) Parent Incarnation: The database incarnation from which the current incarnation branched following an OPEN RESETLOGS operation.iii) Ancestor Incarnation: The parent of the parent incarnation is an ancestor incarnation. Any parent of an ancestor incarnation is also an ancestor incarnation.iv) Sibling Incarnation: Two incarnations that share a common ancestor are sibling incarnations if neither one is an ancestor of the other.

Startup nomount pfile='/data01/init.ora'
run create controlfile script SQL>@create_control.sql
SQL>recover database using backup controlfile until cancel;
then after recovery SQL>alter database open resetlogs

CATALOG vs NOCATALOGthe 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.

You only can get information about one particular database at a time, after connecting with RMAN using target as that particular database.
Suppose there are three db A,B,C.

RMAN> connect target userA/pwd

Now whatever query you will execute will only give information about that database A only.