Your production database is running in the ARCHIVELOG mode and you are using Recovery Manager (RMAN)
with a recovery catalog to perform the database backup at regular intervals. When you attempt to restart the
database instance after a regular maintenance task on Sunday, the database fails to open, displaying the
message that the data file belonging to the SYSTEM tablespace is corrupt.
The steps to recover the damaged data files are as follows:
1. Mount the database
2. Open the database
3. Apply the archived redo logs.
4. Restore the data file
5. Make the tablespace offline.
6. Make the tablespace online.
Which option identifies the correct sequence that you must use to recover the data files?
A.
2, 4, 3
B.
4, 3, 2
C.
1, 4, 3, 2
D.
2, 5, 4, 3, 6
E.
1, 5, 4, 3, 6, 2
How the answer will be “D”. If the system tablespace corrupted then database cannot be mounted.
example:
SQL> startup;
ORACLE instance started.
Total System Global Area 348127232 bytes
Fixed Size 1219328 bytes
Variable Size 289408256 bytes
Database Buffers 50331648 bytes
Redo Buffers 7168000 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 1 – see DBWR trace file
ORA-01110: data file 1: ‘/home/oracle/AZDB/datafiles/system01.dbf’
SQL> exit
[oracle@TEST ~]$ cd backup/
[oracle@TEST backup]$ ls
c1.ctl initAZDB.ora sysaux01.dbf system01.dbf temp01.dbf undotbs1.dbf users01.dbf
[oracle@TEST backup]$ cp system01.dbf /home/oracle/AZDB/datafiles/
[oracle@TEST backup]$ cd
[oracle@TEST ~]$ exit
SQL> shutdown immediate;
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
SQL> startup;
ORACLE instance started.
Total System Global Area 348127232 bytes
Fixed Size 1219328 bytes
Variable Size 289408256 bytes
Database Buffers 50331648 bytes
Redo Buffers 7168000 bytes
Database mounted.
ORA-01113: file 1 needs media recovery
ORA-01110: data file 1: ‘/home/oracle/AZDB/datafiles/system01.dbf’
SQL> recover datafile 1;
ORA-00279: change 373322 generated at 10/31/2008 16:30:29 needed for thread 1
ORA-00289: suggestion : /home/oracle/AZDB/archive/arch_1_669569864_1.arc
ORA-00280: change 373322 for thread 1 is in sequence #1
Specify log: {=suggested | filename | AUTO | CANCEL}
Log applied.
Media recovery complete.
SQL> alter database open;
Database altered
Ans: E
Correct answer is C.
D is wrong beacause System is a critical tablespace => when fail – db can’t start open.
E is not appropriate because db in mount state – restore and recover can take place without taking online of offline at at all.
B. C is wrong because database is already mounted.