2009.1.16_20_21 maitaining control file

Explain the use of control file;

List the contents;

■Control File Contents:
 DB name and identifier;
 Time stamp of database creation;
 Tablespace names;
 Names and locations of data files and redo log files;　
 current online redo log sequence number;
 checkpoint information;
 Begin and end of undo segements;
 Redo log archive information;
 Backup information;
＄strings controlfile | more

■Multplexing the control file when using spfile
SQL>show parameter control
1,alter the spfile
SQL>alter system set control_files='/u01/oradata/wilson/control01.ctl','/u01/oradata/wilson/control02.ctl','/u01/oradata/wilson/control03.ctl' scope=spfile
2,shutdown the database
SQL>shutdown immediate
3,create additional controlfiles
$cp /u01/oradata/wilson/control02.ctl /u01/oradata/wilson/control04.ctl
4,startup the database
startup

■Multplexing the control file when using pfile
1,shutdown the database
2,create additional controlfiles
3,alter the pfile (vi)
4,startup
SQL>create pfile from spfile;

SQL>conn /as sysdba
SQL>startup pfile =$oracle_home/dbs/initWilson.ora
SQL>show parameters

■Using OMF

■Get control file information
・v$controlfile
SQL>desc v$controlfile
SQL>col name format a50;
SQL>select * from v$controlfile
・v$parameter
・v$controlfile_record_section
SQL>desc v$controlfile_record_section
SQL>select type,records_total,records_used from v$controlfile_record_section
SQL>show parameter control_files

■ Creating New Control files
■　Backing up Control files