控制文件用于记录和维护数据库。当恢复数据库时，服务器进程和后台进程需要从控制文件中读取各种备份相关的信息。如果控制文件损

控制文件用于记录和维护数据库。当恢复数据库时，服务器进程和后台进程需要从控制文件中读取各种备份相关的信息。如果控制文件损坏，则会导致这些备份信息的丢失。尽管使用多元化控制文件可以防止控制文件损坏，但因为控制文件的重要性，应该定期备份控制文件。当数据库配置发生改变时，一定要备份控制文件。涉及到数据库配置改变的命令：
alter database [add|drop] logfile
alter database [add|drop] logfile member
alter database [add|drop] logfile group
alter database [noarchivelog|archivelog]
alter database rename file
create tablespace
alter tablespace [add|rename] datafile
alter tablespace [read write|read only]
drop tablespace

控制文件的备份,三种方式
1)使用OS命令进行拷贝
1)open状态下，使用alter database命令生成控制文件副本
2)open状态下，使用alter database backup controlfile to trace命令将控制文件备份到跟踪文件
控制文件的恢复,两种方式
1)mount状态下，使用RECOVER DATABASE USING BACKUP CONTROLFILE
2)mount状态下，生成跟踪文件并进行恢复

2--2示例：

[Oracle@localhost ~]$ rlsqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on 星期一 8月 1 21:40:03 2011

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to an idle instance.

SQL> startup
ORACLE instance started.

Total System Global Area 528482304 bytes
Fixed Size 1220360 bytes
Variable Size 176161016 bytes
Database Buffers 343932928 bytes
Redo Buffers 7168000 bytes
Database mounted.
Database opened.
--open状态下生成控制文件副本
SQL> alter database backup controlfile to
2 '/oracle/10g/oracle/bakup/database/oralife.ctl';
alter database backup controlfile to
*
ERROR at line 1:
ORA-01580: error creating control backup file
/oracle/10g/oracle/bakup/database/oralife.ctl
ORA-27038: created file already exists
Additional information: 1

SQL> alter database backup controlfile to
2 '/oracle/10g/oracle/bakup/database/oralife.ctl' reuse; --reuse用于覆盖原有控制文件副本

Database altered.

--手动删除所有控制文件模拟文件丢失
SQL> ho rm /oracle/10g/oracle/product/10.2.0/oradata/oralife/*.ctl;

--使用evan登录，并添加数据
SQL> conn evan/evan
Connected.
SQL> select * from t_evan;

TEXT
--------------------------------------------------------------------------------
oracle
java
spring
hibernate
hibernate

SQL> insert into t_evan values('added');

1 row created.

SQL> commit;

Commit complete.

SQL> conn / as sysdba
Connected.
SQL> shutdown immediate
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/oracle/10g/oracle/product/10.2.0/oradata/oralife/control01.ctl'
ORA-27041: unable to open file
Linux Error: 2: No such file or directory
Additional information: 3
SQL> shutdown abort
ORACLE instance shut down.

--alter_oralife.log出现这样的信息：
Mon Aug 1 23:13:51 2011
ORA-00202: control file: '/oracle/10g/oracle/product/10.2.0/oradata/oralife/control01.ctl'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3

--拷贝控制文件到目标路径
SQL>ho cp /oracle/10g/oracle/bakup/database/oralife.ctl /oracle/10g/oracle/product/10.2.0/oradata/oralife/control01.ctl

SQL> alter system set control_files='/oracle/10g/oracle/product/10.2.0/oradata/oralife/control01.ctl' scope = spfile; --修改control_files参数，，指定可用的控制文件

System altered.
SQL> startup force mount
ORACLE instance started.

Total System Global Area 528482304 bytes
Fixed Size 1220360 bytes
Variable Size 138412280 bytes
Database Buffers 3816816 bytes
Redo Buffers 7168000 bytes
Database mounted.
--生成trace文件
SQL> alter database backup controlfile to trace noresetlogs;

Database altered.

SELECT c.VALUE || '/' || d.instance_name || '_ora_' || a.spid || '.trc' TRACE
FROM v$process a, v$session b, v$parameter c, v$instance d
WHERE a.addr = b.paddr
AND b.audsid = USERENV ('sessionid')
AND c.NAME = 'user_dump_dest';

TRACE
--------------------------------------------------------------------------------
/oracle/10g/oracle/product/10.2.0/db_1/admin/oralife/udump/oralife_ora_4558.trc

SQL> shutdown immediate
ORA-01109: database not open


Database dismounted.
ORACLE instance shut down.

--打开trace文件，去掉注释，在shutdown状态下执行脚本，创建控制文件

--用evan登录验证数据
SQL> conn evan/evan
Connected.
SQL> select * from t_evan;
TEXT
--------------------------------------------------------------------------------
oracle
java
spring
hibernate
hibernate
added

6 rows selected.
可见数据没有丢失。

SQL> select name from v$controlfile;

NAME
--------------------------------------------------------------------------------
/oracle/10g/oracle/product/10.2.0/oradata/oralife/control01.ctl
这时应该重建多个控制文件。
如何做？

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