Hi DBA-mates,
After long time, again we are back with some important
RMAN utility Questions and Answers. Now a day it is very important to know about the
RMAN details and Configurations.
As per technologies changes, we should also upgrade our
self. Now a day’s RMAN is asking in every profile.
I have selected some very important Questions and
Answers as per my experiences and I have some more questions which I will be
including here soon.
Q1.What is RMAN ?
A.RMAN (Recovery Manager)is an Oracle Database client that
performs backup and recovery tasks on your databases and automates
administration of your backup strategies.
It greatly simplifies the dba jobs by managing the
production database's backing up, restoring, and recovering database files.
Q2.Why to use RMAN ?
A.RMAN gives you access to several backup and
recovery techniques and features not available with user-managed backup and
recovery. The most noteworthy are the following:
-- Automatic specification of files to include in a backup
: Establishes the name and locations of
all files to be backed up.
-- Maintain backup repository: Backups are recorded in the control file,
which is the main repository of RMAN metadata.
Additionally, you can store this metadata in a recovery catalog.
-- Incremental backups:
An incremental backup stores only blocks changed since a previous backup.
Thus, they provide more compact backups and faster
recovery, thereby reducing the need to apply redo during datafile media
recovery.
-- Unused
block compression
: In unused block compression,
RMAN can skip data blocks that have never been used
-- Block
media recovery: You an repair a datafile with only a
small number of corrupt data blocks without taking it offline or restoring it
from backup.
-- Binary
compression: A binary compression mechanism integrated
into Oracle Database reduces the size of backups.
-- Encrypted
backups : RMAN uses backup encryption capabilities integrated
into Oracle Database to store backup sets in an encrypted format.
-- Corrupt
block detection :
RMAN checks for the block corruption before taking its backup.
Q3.How to check RMAN Configuration ?
RMAN>Show all;
Q4.How to Reset to default Configuration ?
A.To reset the default configuration setting use Connect
to the target database from sqlplus and run
SQL> connect <sys/passwd as
sysdba>@target_database;
SQL> execute dbms_backup_restore.resetConfig;
Q5. How Many catalog database I can have ?
A. You can have
multiple catalog database for the same target database . But at a time you can
connect to only 1 catalog database via RMAN. It’s not recommended to have
multiple catalog databases.
Q6. Is this mandatory to use catalog database
?
A. No ! it’s a
optional one.
Q7. What is the difference between catalog database & catalog
schema ?
A. Catalog
database is like any other database which contains the RMAN catalog user's
schema.
Q8. What are the database file's that RMAN
can backup ?
A. RMAN can backup
Controlfile , Datafiles , Archive logs , standby database controfile,
Spfile
Q9. What are the database file's that RMAN cannot backup ?
A. RMAN cannot
take backup of the pfile, Redo logs , network configuration files, password
files, external tables and the contents
of the Oracle home files
Q10. Can I have archivelogs and datafile
backup in a single backupset ?
A. No . we can
not put datafiles and archive logs in the same backupset.
Q11. What is the difference between backup set backup and Image copy
backup ?
A : A backup set
is an RMAN-specific proprietary format, whereas an image copy is a bit-for-bit
copy of a file. By default, RMAN creates backup sets
Q12. Can I take RMAN backup when the database
is Down ?
A. No ! You can take RMAN backup only when the target
database is Open or in Mount stage. Its because RMAN keep the backup metadata
in controfile . Only in open or mount mode controlfile is accessible.
Note: Please Check for Duplicate
RMAN backup and Restore …
Some Important links:
Hope this may useful and helpful. For any concerns
please let us know either in comment box or contact @ora-data.blogspot.com
ref. doc:469777.1
Regards,
ora-data Team
