我们日常对数据库进行配置管理时，为了保证数据库的安全，通常会配置多个控制文件，以防单一控制文件的损坏引起数据库的宕机。如果数据库采用了ASM存储方案，假如只创建一个ASM磁盘组的话，控制文件默认只有一个，这样显然无助于数据库的保护。事实上我们可以通过简单的一些操作把对ASM中的控制文件进行多个配置：

    一、将控制文件从文件系统迁移到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默认只会创建一个控制文件+DATA/test/controlfile/current.1623.640347437，且控制文件的名字由于遵循了ASM的命名方式，比较怪异。我们现在要将名字改为control01.ctl,control02.ctl,control03.ctl这样比较直观的名字。首先对当前控制文件进行一个备份，备份的路径为我们想要的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数据库，然后再对控制文件依样进行备份，更改参数文件，成功地配置了多个控制文件：

    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、通过ASM命令行工具asmcmd可以看到事实上我们设置的控制文件命名规范还是遵照ASM的命名方式的，它会通过一个LINK链接到我们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)

    ASMCMD> ls -alt

    Type Redund Striped Time Sys Name

    CONTROLFILE UNPROT FINE DEC 03 10:00:00 Y none => current.1623.640347437

     N control03.ctl => +DATA/TEST/CONTROLFILE/Backup.5043.640348291

     N control02.ctl => +DATA/TEST/CONTROLFILE/Backup.4733.640348283

     N control01.ctl => +DATA/TEST/CONTROLFILE/Backup.2882.640347745

    CONTROLFILE UNPROT FINE DEC 03 10:00:00 Y +DATA/TEST/CONTROLFILE/control03.ctl => Backup.5043.640348291

    CONTROLFILE UNPROT FINE DEC 03 10:00:00 Y +DATA/TEST/CONTROLFILE/control02.ctl => Backup.4733.640348283

    CONTROLFILE UNPROT FINE DEC 03 10:00:00 Y +DATA/TEST/CONTROLFILE/control01.ctl => Backup.2882.640347745

建议继续学习：

1. ASM使用AIX raw disk的问题    (阅读：3695)
2. Oracle ASM存储方式浅析    (阅读：3199)
3. ASM装载磁盘组时ORA-15063错误处理    (阅读：2517)
4. ASM的争论    (阅读：2269)
5. ASM的争论    (阅读：2232)
6. 用ASM和iSCSI实现的另类HA方案    (阅读：1957)
7. ASM的优点总结–关于日志文件调整    (阅读：1515)
8. ASM HEADER 备份与恢复    (阅读：1458)