multiflexing of control files

Control File Contents

The information in the control file includes:
• Database name is taken from either the name specified by the initialization parameter
DB_NAME or the name used in the CREATE DATABASE statement.
• Database identifier is recorded when the database is created.
• Time stamp of database creation is also recorded at database creation.
• Names and locations of associated data files and online redo log files are updated when
a data file or redo log is added to, renamed in, or dropped from the database.
• Tablespace information is updated as tablespaces are added or dropped.
• Redo log history is recorded during log switches.
• Location and status of archived logs are recorded when archiving occurs.
• Location and status of backups are recorded by the Recovery Manager utility.
• Current log sequence number is recorded when log switches occur.
• Checkpoint information is recorded as checkpoints are made.


Multiplexing the Control File using pfile

1)shutdown the database
2)By using OS command copy the oldfile to newfile
3)In initsid.ora file change this control_file=(oldfilepath,newfilepath')
4)startup the database

SQL>shut immediate
SQL>!
[satish@host oradata]$pwd
/oracle/satish/9i/oradata
[satish@host oradata]$ls
control.ctl redo1.log redo2.log system.dbf undo.dbf
[satish@host oradata]$cp control.ctl control1.ctl
[satish@host oradata]$cd /oracle/satish/9i/dbs
[satish@host dbs]$vi initsatish.ora
#change this parameter
control_files=(/oracle/satish/9i/oradata/control.ctl,oracle/satish/9i/oradata/control1.ctl)
#save and exit
[satish@host dbs]$ cd
[satish@host satish]$sqlplus /'as sysdba'
SQL>start up
then database will be start with two control files
if you want check youer control files use this command
SQL>show parameter control_files


Multiplexing the Control File using spfile

SQL>alter sysytem set control_files='$ORACLE_HOME/oradata/control.ctl','$ORACLE_HOME/oradata/control1.ctl','$ORACLE_HOME/oradata/control2.ctl' scop=spfile;
SQL>shut immediate
SQL>exit
[satish@host satish]$
[satish@host satish]$cd $ORACLE_HOME/oradata/
[satish@host oradata]$pwd
/oracle/satish/9i/oradata
[satish@host oradata]$ cp control.ctl control2.ctl
[satish@host oradata]$cd
[satish@host satish]$sqlplus /'as sysdba'
SQL>startup
then database will be started with 3 control files
if you want see the control file then
SQL>show parameter control_files
or
SQL>select * from v$control_file

--satish