我們日常對數據庫進行配置管理時，為了保證數據庫的安全，通常會配置多個控制文件，以防單一控制文件的損壞引起數據庫的宕機。如果數據庫采用了ASM存儲方案，假如只創建一個ASM磁盤組的話，控制文件默認只有一個，這樣顯然無助於數據庫的保護。事實上我們可以通過簡單的一些操作把對ASM中的控制文件進行多個配置：
一、將控制文件從文件系統遷移到ASM：
SQL> show parameter control_files
NAME TYPE VALUE
------------------------------------
control_files string /home/oracle/control01.ctl, /h
ome/oracle/control02.ctl, /hom
e/oracle/control03.ctl
SQL> show parameter db_create_file_dest
NAME TYPE VALUE
------------------------------------
db_create_file_dest string +DATA
SQL> alter system reset control_files scope=spfile;
alter system reset control_files scope=spfile
*
ERROR at line 1:
ORA-00905: missing keyword
SQL> alter system reset control_files scope=spfile sid=\'*\';
System altered.
SQL> startup nomount
ORACLE instance started.
Total System Global Area 8388608000 bytes
Fixed Size 2086096 bytes
Variable Size 4479519536 bytes
Database Buffers 3892314112 bytes
Redo Buffers 14688256 bytes
dw2:/u01/oracle/product/10g/db/bin>$./rman target /
Recovery Manager: Release 10.2.0.3.0 - Production on Mon Dec 3 10:17:05 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
connected to target database: test (not mounted)
RMAN> restore controlfile from \'/home/oracle/control01.ctl\';
Starting restore at 2007-12-03 10:17:12
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=1091 devtype=DISK
channel ORA_DISK_1: copied control file copy
output filename=+DATA/test/controlfile/current.1623.640347437
Finished restore at 2007-12-03 10:17:21
二、可以看到ASM默認只會創建一個控制文件+DATA/test/controlfile/current.1623.640347437，且控制文件的名字由於遵循了ASM的命名方式，比較怪異。我們現在要將名字改為control01.ctl,control02.ctl,control03.ctl這樣比較直觀的名字。首先對當前控制文件進行一個備份，備份的路徑為我們想要的ASM上的控制文件：
SQL> alter database mount database;
Database altered.
SQL> alter database backup controlfile to \'+DATA/test/controlfile/control01.ctl\';
Database altered.
SQL> alter system set control_files=\'+DATA/test/controlfile/control01.ctl\' scope=spfile;
System altered.
Elapsed: 00:00:00.00
SQL> shutdown immediate
ORA-01507: database not mounted
ORACLE instance shut down.
三、以新的控制文件MOUNT數據庫，然後再對控制文件依樣進行備份，更改參數文件，成功地配置了多個控制文件：
SQL> startup nomount
ORACLE instance started.
Total System Global Area 8388608000 bytes
Fixed Size 2086096 bytes
Variable Size 4479519536 bytes
Database Buffers 3892314112 bytes
Redo Buffers 14688256 bytes
SQL> alter database mount database;
Database altered.
SQL> alter database backup controlfile to \'+DATA/test/controlfile/control02.ctl\';
Database altered.
SQL> alter database backup controlfile to \'+DATA/test/controlfile/control03.ctl\';
Database altered.
SQL> alter system set control_files=\'+DATA/test/controlfile/control01.ctl\',\'+
DATA/test/controlfile/control02.ctl\',\'+DATA/test/controlfile/control03.ctl\' scope=spfile;
System altered.
SQL> startup nomount
ORACLE instance started.
Total System Global Area 8388608000 bytes
Fixed Size 2086096 bytes
Variable Size 4479519536 bytes
Database Buffers 3892314112 bytes
Redo Buffers 14688256 bytes
SQL> alter database mount database;
Database altered.
四、通過ASM命令行工具asmcmd可以看到事實上我們設置的控制文件命名規范還是遵照ASM的命名方式的，它會通過一個LINK鏈接到我們想要的控制文件名字：
ASMCMD> ls
Backup.2882.640347745
Backup.4733.640348283
Backup.5043.640348291
control01.ctl
control02.ctl
control03.ctl
current.1623.640347437
ASMCMD> rm Backup.2882.640347745
ORA-15032: not all alterations performed
ORA-15028: ASM file \'+DATA/TEST/CONTROLFILE/Backup.2882.640347745\
' not dropped; currently being accessed (DBD ERROR: OCIStmtExecute)
