Most Frequently Asked Oracle BPM Interview Questions and Answers
1. Question 1. What Is Level 0,
Level 1 Backup?
Answer :
o
A level 0
incremental backup, which is the base for subsequent incremental backups,
copies all blocks containing data, backing the data file up into a backup set
just as a full backup would. A level 1 incremental backup can be either of the
following types:
o
A differential
backup, which backs up all blocks changed after the most recent incremental
backup at level 1 or 0
o
A cumulative
backup, which backs up all blocks changed after the most recent incremental
backup at level 0
2. Question 2. How Do You Setup
The Rman Tape Backups?
Answer :
Configure channel as SBT_TAPE
and use “ENV” parameter to set the tape configurations.
3. Question 3. What Is The Init
Parameter Specify The Minimum Number Of Days That Oracle Keeps Backup
Information In The Control File?
Answer :
You can use the
CONTROL_FILE_RECORD_KEEP_TIME parameter to specify the minimum number of days
that Oracle keeps this information in the control file.
4. Question 4. What Is The
Difference Between Validate And Crosscheck ?
Answer :
The restore/validate and
validate backupset commands test whether you can restore backups or copies.
You should use:
o
restore : validate
when you want RMAN to choose which backups or copies should be tested.
o
validate backupset
when you want to specify which backup sets should be tested.
5. Question 5. How Do I Go About
Backing Up My Online Redo Logs?
Answer :
Online redo logs should never,
ever be included in a backup, regardless of whether that backup is performed
hot or cold. The reasons for this are two-fold. First, you physically cannot
backup a hot online redo log, and second there is precisely zero need to do so
in the first place because an archive redo log is, by definition, a backup copy
of a formerly on-line log. There is, however, a more practical reason: backing
up the online logs yourself increases the risk that you will lose.
6. Question 6. What Is Backup
Set?
Answer :
RMAN can store backup data in
a logical structure called a backup set, which is the smallest unit of an RMAN
backup. A backup set contains the data from one or more data files, archived
redo logs, or control files or server parameter file.
7. Question 7. What Is Channel?
How Do You Enable The Parallel Backups With Rman?
Answer :
Use the ALLOCATE CHANNEL
command to manually allocate a channel, which is a connection between RMAN and
a database instance. To enable the parallel backups, allocate multiple manual
channels in the run block or configure parallelism
CONFIGURE DEVICE TYPE DISK
PARALLELISM 4 BACKUP TYPE TO BACKUPSET;
8. Question 8. What Is Auxiliary
Channel In Rman? When Do You Need This?
Answer :
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 within the same RUN command. When a Duplicate Database created or table
space point in time recovery is performed Auxiliary database is used. This
database can either on the same host or a different host.
9. Question 9. Is It Possible To
Specific Tables When Using Rman Duplicate Feature? If Yes, How?
Answer :
No, table based recovery not
possible in RMAN duplicate command.
10. Question 10. Outline The Steps
Involved In Cancel Based Recovery From The Full Database From Hot Backup?
Answer :
RMAN doesn’t support
cancel-based recovery like SQL*plus does.
11. Question 11. Outline The Steps
Involved In Scn Based Recovery From The Full Database From Hot Backup?
Answer :
o
startup mount;
o
restore database
UNTIL SCN 233545;
o
recover database
UNTIL SCN 233545;
o
alter database
open resetlogs;
12. Question 12. How Do You Verify
The Integrity Of The Image Copy In Rman Environment?
Answer :
Use below commands
:
o
rman> catalog
datafilecopy ‘f:testsystem.dbf’;
o
rman> backup
validate check logical datafile ‘f:testsystem.dbf’;
o
SQL> SELECT *
FROM v$database_block_corruption;
13. Question 13. Is It Possible To
Take Catalog Database Backup Using Rman? If Yes, How?
Answer :
Recovery catalog is a schema
stored in a database that tracks backups and stores of target databases. So
better to take a export backup.
14. Question 14. How Do You
Identify The Expired, Active, Obsolete Backups? Which Rman Command You Use?
Answer :
Obsolete backups:
o
RMAN> report
obsolete;
expired backup:
o
RMAN> list
expired backup;
o
Active database:
RMAN> list backup;
15. Question 15. Outline The Steps
Involved In Time Based Recovery From The Full Database From Hot Backup?
Answer :
o
startup mount;
o
restore database
UNTIL TIME “TO_DATE(’28/12/2012 18:00:00′, ‘DD/MM/YYYY HH24:MI:SS’)”;
o
recover database
UNTIL TIME “TO_DATE(’28/12/2012 18:00:00′, ‘DD/MM/YYYY HH24:MI:SS’)”;
o
alter database
open resetlogs;
16. Question 16. Explain The Steps
To Perform The Point In Time Recovery With A Backup Which Is Taken Before The
Resetlogs Of The Db?
Answer :
o
We need to list
the database incarnations by using list incarnation command.
o
shutdown the
database
o
startup mount the
database
o
Issue reset
database to incarnation to reset the incarnation.
o
Restore the
database using restore command (e.g restore until scn 23243)
o
recover database
o
Open the database
using resetlogs command
RMAN> list
incarnation of database;
RMAN>reset database to incarnation 5;
run
{
set until scn 234345;
restore database;
rec ….
RMAN>reset database to incarnation 5;
run
{
set until scn 234345;
restore database;
rec ….
17. Question 17. Outline The Steps
For Changing The Dbid In A Cloned Environment?
Answer :
o
shutdown Immediate
o
startup
mount
o
Then, run the the
DBNEWID utility from command line.
o
nid target =/
o
SQL> alter
database open resetlogs;
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18. Question 18. How Do You
Install The Rman Recovery Catalog? Or List The Steps Required To Enable The
Rman . Backup For A Target Database?
Answer :
Steps to be
followed:
o
Create connection
string at catalog database.
o
At catalog
database create one new user or use existing user and give that user a
recovery_catalog_owner privilege.
o
Login into RMAN
with connection string
o
export ORACLE_SID
o
rman target
catalog @connection string
o
rman&g ….
19. Question 19. List Some Of The
Rman Catalog View Names Which Contain The Catalog Information?
Answer :
RC_DATABASE_INCARNATION,
RC_BACKUP_COPY_DETAILS, RC_BACKUP_CORRUPTION, RC_BACKUP_DATAFILE_SUMMARY to
name a few
20. Question 20. What Is The
Difference Between Obsolete Rman Backups And Expired Rman Backups?
Answer :
The term obsolete does not
mean the same as expired. In short obsolete means “not needed ” whereas expired
means “not found.”
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.
21. Question 21. When Do You Use
Crosscheck Command?
Answer :
Crosscheck will be useful to
check whether the catalog information is intact with OS level information.
22. Question 22. If Some Of The
Blocks Are Corrupted Due To System Crash, How Will You Recover?
Answer :
Using RMAN BLOCK RECOVER
command
23. Question 23. You Have Taken A
Manual Backup Of A Datafile Using O/s. How Rman Will Know About It? Or How To
Put Manual/user-managed Backup In Rman (recovery Catalog)?
Answer :
By using catalog
command.You have to catalog that manual backup in RMAN’s repository by
command
RMAN> catalog datafilecopy ‘/DB01/BACKUP/users01.dbf’;
or
RMAN> CATALOG START WITH ‘/tmp/backup.ctl’;
Restrictions:
> Accessible on disk
> A complete image copy of a single file
RMAN> catalog datafilecopy ‘/DB01/BACKUP/users01.dbf’;
or
RMAN> CATALOG START WITH ‘/tmp/backup.ctl’;
Restrictions:
> Accessible on disk
> A complete image copy of a single file
24. Question 24. Where Rman Keeps
Information Of Backups If You Are Using Rman Without Catalog?
Answer :
RMAN keeps information of
backups in the control file.
25. Question 25. What Is The Diff
Between Catalog And Nocatalog?
Answer :
The difference is only who
maintains the backup records like when is the last successful backup
incremental differential etc.
o
In CATALOG mode
another database (TARGET database) stores all the information.
o
In NOCATALOG mode
controlfile of Target database is responsible.
26. Question 26. How Do You See
Information About Backups In Rman?
Answer :
RMAN> List Backup;
27. Question 27. How Do You
Monitor Rman Backup Job Status?
Answer :
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
28. Question 28. How Rman Improves
Backup Time?
Answer :
RMAN backup time consumption
is very less than compared to regular online backup as RMAN copies only
modified blocks.
29. Question 29. What Is The
Difference Between Cumulative Incremental And Differential Incremental Backups?
Answer :
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.
30. Question 30. How Do You Enable
The Autobackup For The Controlfile Using Rman?
Answer :
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 ‘$HOME/BACKUP/RMAN/ F.bkp’; —
$HOME/BACKUP/RMAN/ this can be any desired location.
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