Oracle FAQ
Q.1 When a database is shutdown with shutdown abort command
changes in the memory have been :-
A. Written to the redo log
B. Written to the Datafile
Q.2 How many redo groups are required for a Oracle DB?
A. 1
B. 2
C. 3
D. None
Q.3 What kind of information is stored in UNDO segments?
A. Before Image
B. After Image
C. Both Before and After Image
Q.4 What kind of files are multiplexed?
(Choose 2)
A. REDO Log
B. Control File
C. Datafile
D. UNDO
Q.5 When you apply recover database command, does it get the archived logs from
the backup location?
A. No, only restore command does that.
B. Yes, Recover gets the required archive logs from the backup location.
Q.6 Scenario
DB Mode:- NOARCHIVELOG
Full Backup Taken:- Sunday
Crash :- System datafile got corrupted as there was a cpu failure.
What do you do:-
A. Restore Sundays full backup and loose Monday and Tuesdays data?
B. Look for backups on monday and tuesday and start applying them?
Q.7 Scenario
DB Mode:- ARCHIVELOG
Full Backup Taken:- Sunday
Incremental Backup : Every day
Crash :- System datafile got corrupted as there was a cpu failure.
What do you do:-
A. Restore Sundays full backup and loose Monday and Tuesdays data?
B. Look for backups on monday and tuesday and start applying them?
Q8. To create a pfile from a corrupt spfile the db needs to be at
least in “no mount” state?
A. No you only need to be connected as sysdba
B. Of course for any recovery minimum is “no mount” state
Q9. What is a fractured block?
A. When rman reads a block that is undergoing modification
B. Blocks that are split across extents.
Q10. When ALTER TABLESPACE begin BACKUP command is issued:-
A. No changes are written to the datafile
B. Changes are written to the datafile and the redo stream only the datafile header is not updated.
Q11. If a backup is issued after “shutdown abort” command what kind of backup
is that?
A. Consistent
B. Inconsistent
Q12. You recreated the control file by using backup control file to trace
command, management is happy that you did a good job, what have you lost?
A. All prior backup information
B. Nothing backup information is retained when you recreate controlfile.
Q13. Your site had a ALTER DATABASE BACKUP CONTROLFILE to
‘/safe/deposit/treasure/location/control01.ctl’ and you use this file
to recreate the controlfile what did you loose?
A. All prior backup information
B. Nothing backup information is retained when you recreate controlfile.
Q.14 What do I do if I have a emergency, please help?
A. restore / recover always works
B. look at the alert
Q.15
ANSWERES:-
****************************************************************************
A.1 *B
When you do shutdown abort changes are in memory and are not yet written
to the datafile, when database is opened these changes are applied to the
datafile and the datafiles are brought to a consistent state.
for explaination read
Oracle Doc
A.2 *B
At least 2 redo groups are required for a Oracle database to be working
normally.
A3 *A
Only before image of data is stored in the UNDO segments. If transaction is
rolled back information from UNDO is applied to restore original datafile.
UNDO is never multiplexed.
A4 *A, *B
Only Redo and Control files are multiplexed.
A5 *B
Recover command identifies which datafile(s) are required and gets those files
from the backup location.
A6 *A
In NOARCHIVELOG mode if system tablespace is lost you can only revert back to
the full db backup. If it was any other datafile other than system you can
drop the tablespace loose that tables data and keep working, a decision has
to be made at that time.
A7 *B
The key point to note here is that the system was in archivelog mode so
we can apply the archivelogs and backups taken on sunday and monday and
start applying them.
A8 *A
A9 *A
When rman encounters a block that is undergoing modification it re-reads
the block to ensure that it has obtained a good copy of the block.
A10 *B
A11 *B
It is a inconsistent backup, if you are in noarchivelog mode ensure that you
issue the shutdown immediate command or startup force is another option that
you can issue.
startup force->shutdown abort; followed by shutdown immediate;
A12 *A
You lost all of the backup information.
A13 *B
All backup information is retained when you take binary control file backup.
