This
practice covers determining the name and the location of the controlfile and
multiplexing it.
Where
is the existing control file located and what is the name?
|
SQL>
SELECT *
2 FROM
v$controlfile; STATUS
NAME -------
--------------------------------------
/u01/home/dba01/ORADATA/u01/ctrl01.ctl |
Multiplex
the existing control file, using the directory u02, and name the new control
file ctrl02.ctl.
Hints
Before
shutting down the database alter the SPFILE (SCOPE=SPILE) to add
the new
control file to the initialization file.
Shut
down the database, and copy the existing control file to a new file with the
name ctrl02.ctl in the directory u02.
Start
up the database.
Query
the dynamic performance views V$CONTROLFILE or V$PARAMETER, or use the SHOW
PARAMETER command to confirm that both control files are being used.
|
SQL>
CONNECT / AS SYSDBA Connected. SQL>
ALTER SYSTEM SET control_files
=
'$HOME/ORADATA/u01/ctrl01.ctl',
'$HOME/ORADATA/u02/ctrl02.ctl' SCOPE=SPFILE; System
altered. SQL>
SHUTDOWN IMMEDIATE; Database
closed. Database
dismounted. ORACLE
instance shut down. SQL>
!cp $HOME/ORADATA/u01/ctrl01.ctl
$HOME/ORADATA/u02/ctrl02.ctl SQL>
STARTUP ORACLE
instance started. Database
mounted. Database
opened. SQL>
SELECT name FROM v$controlfile; NAME -------------------------------------- /u01/home/dba01/ORADATA/u01/ctrl01.ctl /u01/home/dba01/ORADATA/u02/ctrl02.ctl |
Why
should a DBA multiplex the controlfile?
To
avoid a single point of failure.
Why
does the database need to be shutdown to copy the controlfile for the purpose
of multiplexing?
Because the controlfile is constantly being updated while the database
is running. The copy would not
agree with the original file when the database is restarted.